MARITIEME'EN OFFSHORETECHNIEK

Het Tijdschrift voor M aritiem e- en Offshore Tech n ie k 'Schip en W e rf is het officiële orgaan van de Nederlandse Ver­

eniging van Technici op Scheepvaartgebied, De Centrale Bond van Scheepsbouwmees­ ters in Nederland CEBOSINE en Het Maritiem Research Instituut Nederland MARIN.

T IJ D S C H R IF T V O O R

MARITIEME'EN OFFSHORETECHNIEK SCHIP EN WERF

Verschijnt vrijdags om de 14 dagen

Redactie P. A. Luikenaar, Dr. Ir. P. van Oossanen, Dr. ir. K. J. Saurwalt en Ing. C. Dam

Redactie-adres Heemraadssingel 193, 3023 CB Rotterdam telefoon 010-4762333

HOE GROOT IS HET OPRICHTEND MOMENT VAN MARITIEM NEDERLAND?

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Reprorecht Overname van artikelen is toegestaan met bron­ vermelding en na overleg met de uitgever. Voor het kopiëren van artikelen uit d it blad is repro­ recht verschuldigd aan de uitgever. Voor nadere inlichtingen wende men zich to t de Stichting Reprorecht. Joop Eijlstraat I I, 1063 EM Am ­ sterdam. ISSN 0036 - 6099 Omslagfoto

De reddingboot „Johannes Frederik" van de Kon. N o ord en Z uid -H olla ndse Redding M ij, De boot is afgeleid van het M edina type en w e rd gebouw d door Aluboot in Hindeloopen. (Foto Cees van d e r M eulen).

Inhoud Hoe groot is het oprichtend moment van maritiem Nederland 235 Major problems in marine engineering and their possible solutions (part 2) 240 Development of a new computer-aided system 248 Nieuwsberichten

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Verenigingsnieuws

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door: Prof. Ir. S. Hengst Indien bij drijvende constructies over een oprichtend mom ent w o rd t gesproken is daarbij een hellingshoek betrokken. De vraag naar de g ro o tte van het moment zou een bepaalde hellingshoek kunnen sugge­ reren die bedreigend is voor de kansen van Maritiem Nederland bij een pessimistische, o f zo men w il, realistische benadering. Bovendien is het een vraag die vragen oproept immers: - wat w o rd t verstaan onder Maritiem Nederland? - bestaat er een oprichtend moment? - waardoor w o rd t het oprichtend mo­ ment bepaald? - (hoe) kunnen w ij het oprichtend m o­ ment meten? - w at doen wij m et de kennis als de g ro o t­ te bekend is? Een kenmerk is de ernstige ondertoon: wat zijn de ontwikkelingen in het vakge­ bied, m.a.w. welke mogelijkheden biedt de toekom st vo or de (jonge) ingenieur. In het vervolg van d it artikel zal een poging w orden gedaan enig inzicht te verschaffen in de ontwikkelingen bij het bedrijfsleven in de maritieme sector, d.w.z. industrie en dienstverlening. Als w ij eind 1987 naar Maritiem Nederland kijken, daarbij de afgelopen 10 jaar be­ schouwen en in het bijzonder de industrie die betrokken is bij het maritieme gebeu­ ren, dan m oet w orden vastgesteld dat v rij­ wel in iedere tak sprake is geweest van ingrijpende veranderingen die in vele ge­ vallen gepaard gingen m et krimpverschijnselen. SenW 55STE IA AR G AN G NR 12

W a t zijn hiervan de gevolgen geweest, hoe ziet de bedrijfstak er thans uit? Zijn alle elementen die kenmerkend zijn voor een maritieme industrie nog steeds aanwezig? W elke zijn die elementen en waaraan kunnen wij zien o f er mogelijkhe­ den van bestaan zijn vo or bedrijven in N e­ derland in deze tak van industrie? Bij een beoordeling spelen een aantal fac­ toren een rol: - de structuur van een industrie; (wat is de samenstelling van de vloot) - de positie van de bedrijven; (hoe g ro o t is het draagvermogen, w at is de statische stabiliteit) - de dynamiek van de bedrijven, beschikt men over voldoende fle x ib ilite it om de voortdurende veranderingen te volgen; (de dynamische stabiliteit) - de omgevingscondities waarin de be­ drijven moeten werken; (aan welke eisen m oet het schip voldoen) - de markten waarin de bedrijven ope­ reren; (welke lading w o rd t aangeboden) - de vorm waarin het bedrijf zich presen­ te ert, is het kennis intensief, een aanne­ m er (jobber), een gespecialiseerd produktiebedrijf etc.; (waar ligt het drukkingspunt en w at is de waterverplaatsing) - de produkten die de bedrijven in de m arkt aanbieden; (waar ligt het zwaartepunt) - de kw alite it van het personeel; (de bemanning) 235

de vernieuwingen die to t stand worden gebracht en de veranderingen die daar­ voor nodig zijn; (hoe kunnen draagvermogen, statischeen dynamische stabiliteit w orden aange­ past aan nieuwe eisen). De parallel m et het oprichtend mom ent is - naar ik hoop - duidelijk en de taak is vervolgens de bovengenoemde aspecten en elementen in kaart te brengen, om daarmee tenslotte een antw oord te kun­ nen geven op de vraag naar de g ro o tte van het oprichtend vermogen. Een aantal van de vragen die aan het begin van d it artikel werden gesteld zijn meer o f minder beantwoord. In hoeverre de aanna­ mes juist zijn zal in k o rt bestek nader worden onderzocht. Rest nog de vraag: -

W a t is M a ritie m N e d e rla n d en w a a ru it b estaat het? STELLING: Maritiem Nederland is e r w el maar bestaat niet, althans niet in een vorm waarin het aanspreekbaar is. M aritiem Nederland is een stelsel van verschillende bedrijfs­ takken en belangen waarbinnen vele, u it­ eenlopende bedrijven, instituten, semioverheids- en overheidsinstellingen w e rk­ zaam zijn en waar meerdere ministeries van de overheid bij betrokken zijn. De gemeenschappelijke noem er is de b e tro k­ kenheid m et de zee en de binnenwateren. Een stelling vraagt om bewijsvoering en daarvoor w o rd t hier onder meer verw e­ zen naar de literatuur waarin de relatie tussen de bedrijfstakken w o rd t behandeld. De samenhang van M aritiem Nederland w o rd t door ir. W . te r H art in de Eerste Verolme lezing ( I ) behandeld. De lezing geeft een beeld van vrijw el ieder gebied van de maritieme activiteiten in Nederland en een globaal overzicht van potentiële ontwikkelingen, maar gaat niet in op de sterke en zwakke zijden van de industrie. De mogelijkheden vo or de scheepsbouw in Nederland en W est-Europa worden globaal behandeld in (2), (3) en (4), echter het totaalbeeld van de Maritieme Industrie in Nederland ko m t in deze artikelen niet aan de orde. Daarom volgt een k o rt overzicht om iets meer inzicht in de samenstelling van Mari­ tiem Nederland te geven. De veranderin­ gen op economisch gebied hebben invloed op de mogelijke kansen en bedreigingen van een industrie en worden bij het volgen­ de overzicht betrokken. D e econom ische veran derin g en Transport en distributie Sedert een aantal jaren zijn de langzaam optredende veranderingen in de economi­ sche structuren in de w ereld duidelijk zichtbaar geworden. De economische groei, de handel en daarmee de technologi­ sche ontwikkelingen verschuiven van de landen om de N o o rd Atlantische oceaan naar de gebieden rond de Pacific. 236

Scheepvaart en Scheepsbouw; de chemicaliëntanker 'Calluna ’ verlaat de 'Ysselw erf In eerste instantie is de scheepsbouw in West-Europa daarvan in de jaren ’70 het slachtoffer geworden (2). De verschuiving heeft in tweede instantie z'n effect op vrijw el alle bedrijven en activiteiten van bedrijven in West-Europa en tre ft ook de niet maritiem gebonden industrieën, de invloeden daarvan zijn terug te vinden in een g ro te r wordend protectionism e met als gevolg geen o f weinig groei in de w e ­ reldhandel en een teruglopende vraag naar transportmiddelen d.w.z. schepen. De Westeuropese scheepvaart w o rd t in toenemende mate geconfronteerd m et de concurrentie u it de N.I.C.’s (de newly industrializing countries). D it is eveneens aan de orde voor de niet maritieme bedrijven, die zich vaak in de betrokken landen vesti­ gen en daardoor kans zien een aandeel in de wereldmarkten te behouden. De transport- en transitosector is echter niet u it Nederland weg te denken. De positie van een haven als Rotterdam is daarin van wezenlijk belang en verdient bijzondere aandacht. Maar Nederland Dis­ tributieland beschikt over meer; een aantal havens die in samenhang m et het vervoer door de lucht (SCHIPHOL), over het land (rail en weg) en vooral niet te vergeten over het w ater (de binnenvaart) geogra­ fisch en infrastructureel een sterke positie kunnen bezorgen. Een positie waarvoor geknokt zal moeten w orden w il hij behou­ den blijven, o o k in West-Europa ligt de concurrentie op de loer en verschuiven de vervoersstromen naar het zuiden. De dienstverlening zal ook v.w.b. de m aritie­ me voorzieningen optimaal moeten zijn en er is b.v. zeker plaats v o o r enkele goed geoutil leerde scheepsreparatiebed rijven in de havens. H et belang van de vervoerssector w o rd t w ellicht het beste geïllustreerd door de volgende cijfers: de sector is goed voor 6% van het nationale inkomen, 5% van de werkgelegenheid en 14% van het over­ schot op de betalingsbalans.

DE N A T T E P O T E N S cheepvaart Scheepvaart v o rm t een in tegreren d deel van de handels-, ve rvo e rs- en d is trib u tie ­ keten. M et name v o o r de kleine handels­ vaart is een N ederlandse (o f W est-E uropese) scheepsbouw van belang.

Bedreigingen: - de groei van de w ereldhandel is beperkt - de capaciteit is g ro te r dan de vraag - concurrentievervalsing (subsidies, p ro ­ te c tie , kw aliteitsverschillen etc.) - ve rm in d e rin g overheidssteun.

Kansen: - specialisatie - geïntegreerde land).

aanpak

(w a te r,

lucht,

Scheepsbouw D e g ro te scheepsbouw is (vooralsnog) v o o r N ederland v e rlo re n . V o o rlo p ig zal de e x p o rtp o s itie niet ve rb e te re n , gezien de subsidiepolitiek in de overige E.E.G. lan­ den. H e t kleine aandeel in de w e re ld m a rk t b e te ke n t dat deze industrie w e re ld w ijd geen m a rktb e ïn vlo e d e r m eer is. De scheepsbouw zal de belangrijke impulsen to t de technologische vernieuw ingen uit de defensie-opdrachten m oeten krijgen tenzij de o verheid bereid is bijzondere m aatregelen te tre ffe n v o o r de vernieu­ w ingen in de bedrijfstak. De banden m e t de N ederlandse reders zullen op basis van w ederzijds belang m oeten w o rd e n aange­ haald.

Bedreigingen: de N ederlandse reders kopen in het buitenland - capaciteit g ro te r dan de vraag - concurrentievervalsing (subsidies, p ro ­ te c tie etc.) - w egvallen vervangende m arkten. -

SenW 55STE jA A R G A N G NR 12

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produktie - concurrentievervalsing.

S c h e e p s re p a ra tie

Kansen: - nieuwe vormen van samenwerking in het buitenland.

Kansen: specialisatie _ concurrentiepositie _ kw aliteit.

Het beschikbaar hebben van scheepsrepa­ ratie is van vitaal belang v o o r iedere zeeha­ ven. De vo rm waarin de reparatie in N e ­ derland uite in de lijk zal overleven is ste rk afhankelijk van een aantal niet bedrijfsge­ bonden factoren. D e bedrijfstak w o r d t on ­ derm eer g e ke n m e rkt d o o r sterke flu c tu ­ aties in het aanbod van w e rk . De bedrijfs­ voering zal daarop m oeten kunnen inspe­ len. In het bijzon der zal daarnaast d o o r de bedrijven g ro te aandacht aan de p ro d u k tiv ite it (in de ruim ste betekenis van het w o o rd ) m oeten w o rd e n geschonken.

Bedreigingen: - capaciteit g ro te r dan de vraag - concurrentievervalsing - wegvallen vervangende m arkten.

Kansen: - specialisatie - goede po te n tië le m a rk t - goede infrastructuur. B in n e n v a a rt W aarschijnlijk v o rm t de binnenvaart één van de sterkste tro e v e n v o o r de tra n s p o rt­ en tra nsitopo sitie van N ederland. R o tte r­ dam dankt zijn s te rk te v o o r een belangrijk deel aan de m ogelijkheden van h e t trans­ p o rt ove r binnenw ateren. Ondanks de hui­ dige overcapaciteit zal de binnenvaart mee moeten in de veranderingen die de geïnte­ greerde transportsystem en m e t zich mee brengen. De m ogelijkheden v o o r de schipper-eigenaar m oeten w o rd e n v e rg ro o t.

Bedreigingen: - capaciteit g ro te r dan de vraag - achterblijvende infrastru ctu u r.

Kansen: - geïntegreerde transportsystem en - verleggen van term inals naar het binnen­ land - specialisatie.

Voedselvoorziening T o t nu to e is de visserij een p o sitie f draai­ ende bedrijfstak geweest. O o k deze bran­ che o n tk o m t thans n ie t aan sanering, v o o r­ namelijk t.g.v. de verm in d e rd e p ro d u k tie mogelijkheden. De gevolgen v o o r de scheepsbouw zijn dat - op een u itzondering na - de o rd e rs op k o rte te rm ijn zullen uitb lijve n tenzij de visserijen op g ro te re schaal zullen in te rn a ­ tionaliseren. O o k in deze bedrijfstak neemt opslag, tra n s p o rt en d is trib u tie een steeds belangrijker plaats in.

Bedreigingen: - capaciteit g ro te r dan de toegestane

SenW 55STE IA AR G AN G NR 12

Energie, offshore Het uiteenvallen van de OPEC, m et als gevolg een dalende olieprijs heeft de aan­ dacht van de oliemaatschappijen verlegd van de zee naar het land. In Nederland gaf dit aan het eind van ’84 een sterke terugval in de offshore-activiteiten te zien. Gecom­ bineerd m et het toenemende p ro te ctio ­ nisme houdt d it v o o r de Nederlandse be­ drijven in dat opdrachten in scherpe con­ currentie moeten w orden verkregen, als gevolg van de overcapaciteit, te rw ijl de afzetmogelijkheden op de N oordzee te ­ ruglopen. Bedreigingen: - voortdurend protectionisme - mogelijke technologische achterstand v.w.b. de nieuwe ontwikkelingen - overcapaciteit in de produktie van olie (het aanbod is g ro te r dan de vraag). Kansen: - aanwezigheid van een grote oliemaat­ schappij in Nederland - uitbuiten van de kennis en ervaring. De overige sectoren vertonen een s o o rt­ gelijk beeld, en w orden hier niet verder behandeld (kustverdediging, nat grond­ verzet, defensie etc.). De bijdrage aan de maritieme sector is van gelijk belang, waar­ bij opgem erkt m oet worden dat N eder­ land op het gebied van het baggeren en het bouwen van het baggermaterieel een w e­ reldnaam heeft en gedurende een lange periode commercieel en technologisch als internationaal m arktleider w o rd t gezien. Een uitzondering v o rm t de recreatiesec­ to r waarin nog steeds goede vooruitzich­ ten zijn alhoewel de val van de koersen en de dollar op ko rte term ijn een negatieve invloed zouden kunnen hebben. Enkele conclusies U it d it beknopte overzicht kunnen enkele conclusies w orden getrokken die betrek­ king hebben op het geheel van de m aritie­ me bedrijfstakken en niet beperkt zijn to t Nederland. De verschillen tussen de Vere­ nigde Staten, W est Europa en de industrie­ landen in het Verre Oosten komen niet aan de orde. de overcapaciteit Op bijna alle gebieden is de produktie capaciteit te g ro o t en deze situatie bepaalt voor een belangrijk deel de o ntw ikkelin­ gen in de markten (ondanks alle subsidies), nl. een felle concurrentie m et een laag prijsniveau. Indien sprake is van een struc­ tureel verschijnsel (b.v. N IC ’s blijven scheepswerven bouwen en nieuwe tonna­

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ge aan de w ereldvloot toevoegen) kan herstel lang op zich laten wachten: er m oet worden gerekend in decennia. De oorza­ ken van de overcapaciteit zijn voor een deel de zelfde: 1. Schaalvergroting, de toename van de capaciteit per eenheid (grotere sche­ pen en werven). 2. Rendementsverbetering, grotere ca­ paciteit per eenheid (betere schepen en werven), vo or een deel het gevolg van verbeterde technieken en organisaties. 3. Eerdere vervanging dan economisch of bedrijfstechnisch noodzakelijk was t.g.v. subsidies, m et b.v. in de scheep­ vaart als gevolg een g ro te r aanbod in de tweede-hands markt. 4. De vervoerscapaciteit w erd beïnvloed door incidentele oplevingen in de vrachtprijzen, w at to t overijlde bestel­ lingen leidde. 5. Verbeterde bedrijfsvoering, als gevolg van de mogelijkheden to t de invoering van nieuwe technologieën, stimuleerde nieuwe bestellingen (bemanningsreducties). protectionism e V rijw el de gehele m aritieme sector w o rd t geconfronteerd m et protectionistische maatregelen, die vo o r een belangrijk deel het gevolg 'zijn van de overcapaciteit: iedereen m oet inleveren, niemand w il, er bestaat geen volwassen internationale overlegstructuur die ordenend kan o p tre ­ den. Kennelijk is de maritieme bedrijfstak van strategisch belang en w il iedere zich ’m aritiem ’ noemende natie de bedrijven in deze sector handhaven en beschermen. -

subsidies Ten einde de (beschermde) industrieën en dienstverlenende bedrijven in W est-Europese landen in de internationale markten concurrerend te laten opereren worden door de overheden subsidies verstrekt. De ondersteuning vond eveneens plaats indien het beleid t.a.v. de werkgelegenheid daar­ toe noopte. De gevolgen daarvan waren b.v. merkbaar in bouwprogramma’s voor werven die gerealiseerd werden m.b.v. versnelde programma’s van vernieuwin­ gen van vloten. H et Nederlandse beleid was gericht op een langzame maar zekere afbouw van de capaciteit van de scheepsbouw, hoewel aanvankelijk getracht is d.m.v. schaalver­ groting bij de bedrijven de internationale ontwikkelingen bij te houden. Deze pogin­ gen zijn mislukt en het Nederlandse beleid is thans gericht op het realiseren van een zo snel mogelijke afbouw van de subsidies in de EEG, to t nu to e zonder enig merkbaar resultaat. Zijn er dan nog wel mogelijkheden vo or de Nederlandse Maritieme bedrijfstak? De bovengenoemde ’kansen’ geven een indicatie, maar zeggen in wezen weinig over ’het oprichtend m om ent’. -

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Daarvoor is een nadere beschouwing van de bedrijfstak nodig. D e s tru c tu u r van de m a ritie m e in­ dustrie U it het bovenstaande overzicht blijkt dat de structuur van de Maritieme industrie veelomvattend is en een sterke indruk maakt. De samenstelling van het maritieme wereldje in Nederland is pluriform , het aandeel in de wereldm arkten is soms g ro o t (bagger), er is ruime ervaring en bijna over­ al is sprake van het gebruik van geavanceer­ de technieken. De pro du ktiviteit ligt in verhouding to t de overige EEG-landen op een hoog niveau (b.v. de scheepsbouw). De verwachting is dat d it voorlopig wel zo zal blijven, alhoewel de verschijnselen van krim p nog niet geheel ten einde zijn. Er zijn echter een aantal ’zwakke’ plaatsen b.v.: - Nederland neemt niet deel aan R&D op het gebied van diepzee onderzoek, - de aansluiting op offshore gebied dreigt verloren te gaan m.b.t. de o ntw ikkelin­ gen op sub-sea gebied, - aartVankeljke deelnames op het gebied van 'sea mining’ zijn verlaten. De traditionele industrieën blijven moei­ zaam drijvende maar zijn niet geheel zon­ der vooruitzichten. V o o r de Nederlandse scheepsbouw bete­ kent d it dat er een (kleine) thuism arkt blijft bestaan. D e positie van de bedrijven In het algemeen is de omvang en het eigen vermogen van de scheepswerven drastisch gereduceerd. Soms heeft d it geresulteerd in een geringere aanvangsstabiliteit, waar­ door de gevoeligheid voor de omgevings­ condities g ro te r w erd, soms in een grotere aanvangsstabiliteit m et een geringere stabiliteitsomvang, w aardoor het gedrag tij­ dens slecht w eer w at onplezieriger werd. H et schermen met een gro te aanvangstab ilite it is sommigen noodlottig geworden toen bleek dat de stabiliteitsomvang te beperkt was. Sommige scheepvaartbedrijven hebben kans gezien d.m.v. een gro tere diepgang meer draagvermogen te verkrijgen, ande­ ren zijn geconfronteerd m et een verm in­ dering. De aanvangsstabiliteit is echter in het algemeen niet aangetast. Een g ro o t (draag)vermogen vraagt om grote (hoofd)afmetingen; in Nederland bleekdit niet altijd succes op te leveren. De omzetting naar kleinere eenheden lijkt op korte term ijn een gro tere slagvaardigheid en dynamiek op te leveren, de betekenis van het Nederlandse bedrijfsleven in de internationale markten is daarmee echter afgenomen en er zullen flexibele en dyna­ mische samenwerkingsvormen gevonden moeten w orden om een sterke internatio­ nale positie te kunnen behouden o f her­ winnen. 238

D e d yn am iek van de bedrijven De wijze waarop een onderneming op de voortdurende veranderingen van de om ­ geving reageert kan weergegeven w orden door het begrip ’dynamiek’. Een te snelle reactie kan evenzeer schadelijk blijken te zijn als een te trage. H et oprichtend mom ent w o rd t bij de be­ oordeling van de statische stabiliteit be­ paald door de ligging van het zwaartepunt (welke van de produkt/m arkt combinaties is het belangrijkst) en het drukkingspunt (de vorm ), het traagheidsmoment - de breedte speelt een belangrijke rol - (wil het bedrijf in de breedte in verschillende markten werken) en de waterverplaatsing (de omvang), waarbij de g ro o tte van het oprichtend moment w o rd t beïnvloed door omgevings- en operationele condi­ ties. H et oprichtend moment kent bij een verstoring van het evenwicht statisch ge­ zien tw ee evenwichtstoestanden, w at to t onduidelijkheden kan leiden. H et oprich­ tend vermogen kom t beter to t uiting bij een beschouwing van de krom me van dy­ namische wegen. De 'dynamische stabili­ te it’ is een goede maatstaf omdat daarmee tevens het begrip ’arbeid’ aan de orde is. D e omgevingscondities De ondernemingen die in Nederland ge­ vestigd zijn hebben te maken m et N eder­ landse omstandigheden Deze zijn soms gunstig (de geografische ligging m et goede verbindingen naar het achterland, de aan­ wezigheid van ’s werelds grootste haven, natuurlijke rijkdommen op het gebied van energie, redelijk stabiele sociale verhou­ dingen etc.), soms minder gunstig (hoge loonkosten, een veelheid aan regelgeving, hoge sociale lasten etc.). De invloed op het oprichtend vermogen kan als gevolg van die omstandigheden sterk variëren van on­ derneming to t onderneming. Een gevolg van de hoge lasten is het terug­ dringen van activiteiten die arbeidsinten­ sief zijn d.m.v. automatisering en robotise­ ring. D it gaat gepaard m et veranderingen in de structuur van de industrie en de onderneming, de vraag naar een hoog­ waardiger produkt en de noodzaak to t een intensievere bewerking van de markt. De dynamiek van een onderneming w o rd t be­ paald door de fle x ib ilite it waarmee aanpas­ singen, die het gevolg zijn van de verande­ rende omgevingscondities, worden d o o r­ gevoerd. V o or de scheepsbouw- en offshore indus­ trie is de industrieële infrastructuur van g ro o t belang. Deze industrieën zullen meer en meer het karakter krijgen van assemblage bedrijven die in nauwe samen­ werking m et gespecialiseerde toeleveringsbedrijfen, soms in een vorm van 'comakership’, produkten samenstellen. Het zijn dan geen leveranciers meer van de traditionele produkten. H et produkt w o rd t ’project management’, d.w.z. de perfecte beheersing van organisatie en de

daarbij behorende logistiek. De bouw­ plaats verschuift in die opstelling naar het tweede plan en is uitsluitend afhankelijk van de eisen die de contractpartner stelt, de kosten en de kwaliteit. De conclusie kan niet zijn dat sprake is van 'slecht w ee r’, wanneer de omstandighe­ den aanpassingen eisen. Een strategische planning, het tijdig verleggen van de koers met duidelijke aanwijzingen v o o r de be­ trokkenen, kan paniekreacties voor­ komen. D e m a rk t O p lange term ijn gezien zijn de maritieme markten stabiel. Transport en distributie, energie, voedsel, defensie, civiele werken t.b.v. kustverdediging, recreatie etc. zul­ len, zeker waar het de maritieme toepas­ singen betreft, een permanente vraag naar vaartuigen en diensten opleveren. Er is geen sprake van ’sunset’ industrieën. Daar­ mee is ook de grote belangstelling ver­ klaard die b.v. ontwikkelingslanden voor deze industrieën hebben. Naast de oplei­ ding van hoogwaardig vakmanschap over een breed gebied is vaak sprake van een redelijke m arkt vo o r eigen behoeftedekking op langere term ijn. De industrie kan hierop inspelen. V o or de scheepsbouw is de verdergaande integratie van de transport en distributie­ sector van belang. De noodzaak to t be­ heersing van de integrale transport en distributiekosten zal ook nieuwe eisen aan de transportmiddelen stellen. D e v o rm van een b e d rijf Er zijn verschillende vormen waarin een bedrijf zich kan presenteren. Deze vorm is afhankelijk van factoren als b.v.: - het bedrijfstype (produktie o f dienst­ verlenend), - het marktsegment waarop het zich richt, - de omvang van de m arkt (b.v. lokale- of wereldmarkten), - soort produkt(en) - karakter en kenm erk van de produkten, - kapitaalsbehoefte, - de mate waarin R&D van belang is voor vernieuwing - de afmetingen van het bedrijf, - de beschikbare infrastructuur etc. De ligging van het ’drukkingspunt’ w o rd t bepaald door de ’v o rm ’, de aanvangsstabili­ te it is vooral afhankelijk van de breedte bij eenzelfde waterverplaatsing. De afmetin­ gen (het draagvermogen) w orden echter vaak bepaald d oo r de beschikbare financie­ ring. De vorm eist derhalve veel aandacht. Er zijn vele variabelen en in de literatuur is hierover veel te vinden. Een interessante aanzet geeft P orter (5) in 'C om petitive Strategies’, waarin de relatie tussen omge­ vingscondities en bedrijfsvorm w o rd t be­ handeld. H et onderzoek op d it gebied is hoofdzakelijk gericht op consumptiegoe­ deren. M et betrekking to t de zware indus­ SenW 5SSTE IA A R G A N G NR 12

trie is vo or de Rijnmond een studie uitge­ voerd (6). Voor constructiebedrijven en scheeps­ werven kan globaal de volgende indeling worden gemaakt: 1. Bedrijven die zich richten op produktie tegen de laagst mogelijke kosten, met een 'uitgeknepen' organisatie, en w ei­ nig o f geen ontwerpmogeijkheden en een geringe overhead hebben, de zgn. jobbers, 2. Bedrijven die zich richten op gespeciali­ seerde produktieprocessen, de kennis van het produktieproces is bepalend (b.v. voorbew erking van platen en p ro ­ fielen), 3. Produktgerichte bedrijven m et het ac­ cent op marketing en verkoop (dit is to t nu toe alleen m ogelijk gebleken voor kleine vaartuigen), 4. Bedrijven die zich richten op de p ro ­ jectorganisatie, b.v. offshoreconstructie, 5. Kennisintensieve bedrijven, meestal gespecialiseerd op een hoogwaardig produkt in een specifieke markt, b.v. de baggerindustrie, 6. Produktie t.b.v. defensie (marine). Deze bedrijfsvormen zijn alle nog in N e ­ derland aanwezig en zijn meestal t.g.v. de m arktontwikkelingen teruggebracht to t Energie, offshore; het Ekofisk Complex.

de ondergrens w at de afmetingen betreft. Daarmee is de breedte en dus ook de aanvangsstabiliteit gereduceerd.

ren van R&D en produktontw ikkeling (de hellingshoek meten en middelen aanreiken om te voorkom en dat het schip kentert).

D e p ro d ukten en de m a r k t De ligging van het drukkingspunt en het zwaartepunt hebben een nauwe relatie. Een goede afstemming tussen de vorm en de produktm arkt combinaties is vereist. De thans nog beschikbare kennis en erva­ ring staat hiervoor borg. Produkten en markten lijken in de m aritie­ me sector erg 'vo o r de hand liggend’ te zijn. Toch kwamen de initiatieven soms uit andere sectoren, zowel op het gebied van de technologie als de opzet van nieuwe systemen. De verdergaande integratie van de transport- en distributiesystemen, met als doel enerzijds kostenreducties d.m.v. de optimalisering van het proces en ander­ zijds beheersing van de m arkt kan de aanlei­ ding vormen to t verdergaande pro du kt­ en systeemvernieuwingen. De startpositie van Nederland is goed omdat in de infra­ structuur alle elementen (nog) aanwezig zijn. Bij verder afkalven daarvan is een snel en op maat gesneden antw oord op nieuwe o n t­ wikkelingen vrijw el uitgesloten, de over­ heid heeft een taak bij het ontw ikkelen van de industrieële infrastructuur en stimule­

V ern ieu w in g en De aanpassingen die nodig zijn om een bedrijfssector en de ondernemingen te vernieuwen gaan vaak gepaard m et harde en onplezierige maatregelen. Er kan sprake zijn van geleidelijke veranderingen (als de m arkt het toelaat) maar ook van sloop en in het laatste geval is het maar de vraag o f er w eer nieuwbouw volgt. De theoretisch meest gewenste oplossing is een vo ortdu ­ rend proces van geleidelijke veranderin­ gen. Daarbij moeten alle stabiliteitscriteria nauwlettend in het oog w orden gehouden. De praktijk is vaak een te late en onvolledi­ ge aanpassing. Daarmee loopt het oprich­ tend moment vaak het gevaar te klein te worden: - er is sprake van verlies aan draagver­ mogen - gebrek aan dynamiek en fle xib ilite it - de omgevingscondities werden niet goed ingeschat etc. Vernieuwingen dienen een permanent on­ derdeel uit te maken van de bedrijfsstrategie en hebben betrekking op alle facetten van een onderneming: markten, produk­ ten, technologie, structuur, vorm, organi­ satie, personeel etc. en zijn nodig om de kansen op de continuïteit van een onderne­ ming zo g ro o t mogelijk te maken. Ideeën daarvoor w orden aangedragen door mensen die betrokken zijn bij het vak en het bedrijf. De ondernemingen m et de grootste dyna­ mische stabiliteit zijn vaak die ondernemin­ gen die mensen w eten te stimuleren en motiveren, beschikken over leidinggevend personeel dat open staat vo or vernieuwin­ gen. In de maritieme sector in Nederland zijn er daarvan voorlopig nog wel enkele te vinden. Eén van de taken van de universiteiten is de jonge generatie de smaak van de uitdaging te leren kennen - onder de zwaarste om ­ standigheden is de uitdaging ook het g rootst - en daarmee eveneens bij te dra­ gen aan het vergroten van het oprichtend moment. L ite ra tu u r 1. Ir. W. te r Hart, Ie Verolme lezing, nov. 1986. 'Heeft Maritiem Nederland een kansrijke Toe­ komst achter de Rug'. 2. Hengst, Prof. ir. S.: Scheepsbouw nu en straks. Tweede Tideman Herdenking 1982. 3. Hengst. Prof. ir. S.: Shlp Production. The Search fo r Specialization in Unique Product Manufacturing. June 1987,6th W EMT Symposium 'Advances in Ship Design and Production'. 4. Hengst, Prof. ir. S.: Systematic Research in Manufacturing o f Ships: not done o r impossible, CETEN A Oct. 1987. 5. Porter, Michael E.: Competitive Strategy, The Free Press 1980. 6. Groen C. J., Roberts, H. H. E.: Uitstraling van de zware Industrie in het Rijnmondgebied, aug. 1986.

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OVERVIEW OF PRESENT DA Y A N D FUTURE MAJOR PROBLEMS IN MARINE ENGINEERING A N D THEIR POSSIBLE SOLUTIONS* (p a rt 2) by: A. de Moo/** (continued from page 222) F U ELS IN D IE S E L E N G IN E S In tro d uctio n In consequences o f the oil crisis in the seventies, fuel is the challenge to the diesel engine fo r the second tim e since its inven­ tion and very first trials in the late nineties o f the previous century. Although todays challenge is influenced by factors which are different from those o f the late forties and early fifties, the effects are more o r less o f comparable nature. Throughout its existence fuel quality and specific fuel consumption, have been im­ portant operational factors, which are strongly related to o the r im portant fac­ tors such as reliability, maintenance, life tim e and number and skill o f personnel. N ever before in the history o f the diesel engine, has development w o rk changed so suddenly. Concentration on achieving high specific output has been replaced by focus­ ing o f attention on high thermal efficiency and burning o f low quality fuels. It is not the intention in this chapter to outline the information in great detail, that already exists, but merely to describe the problems and todays remedies, w ithin the scope o f this paper. P ro b lem The main factor, that caused the problem in the first ’fuel effort* during the fifties, was the form ation o f combustion products, which w ere corrosive at high o r low temperature. The break-through came w ith the applica­ tion o f alkaline cylinder lubricating oil and adequate coating o f surfaces exposed to the corrosive products. The amount and nature o f the corrosive combustion products could be fairly well estimated by chemical analysis o f the fuel. The causes o f the problems encountered since the seventies, that could be desig­ nated as the second ’fuel e ffo rt’ are more * Paper presented at the International Marine Engineering Conference in Shanghai, China, Nov. 4-7,1987. ** Netherlands Organization fo r Applied Scientific Research, Inst, o f Mechanical Engineering TNO /IW EC O , Delft.

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complicated. Practical experience and laboratory tests have shown, that the con­ ventional physical and chemical fuel analysis does not give sufficient and reliable indica­ tion o f the quality o f ignition and the subse­ quent combustion as well as o f the effects o f the combustion products on the engine performance. Analysis o f fuel related engine troubles indicate, that heavy fuels, which according to high Conradson Carbon Residue (CCR) values and large contents o f asphaltenes, should be classified as ’bad’ fuels, do not necessarily create any operational prob­ lems, while fuels w ith comparatively low CCR values and asphaltene contents may cause severe deposit form ation and wear o f vital engine components. The results o f a large number o f laboratory tests carried o ut in different countries on different engine types w ith various heavy fuels have shown, that only small and insig­ nificant deviations in the traditional para­ meters used fo r combustion characterisa­ tion occur. These traditional parameters used to evaluate the combustion process com ­ prise: - maximum cylinder pressure - mean effective pressure - temperatures o f the combustion space walls - injection pressure and injector needle lift curve - heat radiation. Because long term tests showed very diffe­ rent results w ith respect to deposit form a­ tion and subsequent fouling, there had to be differences in the combustion process in some way. In conclusion, the definition of the heavy fuel quality cannot be based on the trad i­ tional fuel analysis data alone. O th e r means have to be found to predict the effect o f the fuel used on the engine performance under various load and en­ vironmental conditions. The research w o rk carried o ut by manu­ facturers and institutions, so far indicate, that the combustion o f fuels in diesel en­ gines is a far m ore complicated process than has been realised.

Intensified fundamental research has to be carried o ut on laboratory engines and simulation facilities, such as a constant volume combustion bomb. Also a theoretical approach using mathematical models could contribute to a b etter understanding o f the combustion process and the factors influencing the phenomena preceding the combustion. So far experiences in the laboratory and onboard ship w ith bad fuels have shown that, poor ignition and slow combustion of these fuels, resulting in long delay tim e and delayed completion o f combustion are the causes o f severe damage to engines such as broken piston rings, damage to the piston ring zone and ring carriers, which occa­ sionally have led to crank case explosions. This can be understood, if it is realised, that the delays lead to both increased mechani­ cal and thermal load. The mechanical load w ill increase due to increased maximum cylinder pressure as a result o f the in­ creased amount o f premixed fuel and the thermal load due to the longer duration of the combustion phase {after burning). A ’good’ quality heavy fuel w ill reach its maximum radiation level almost im­ mediately after ignition and maintain it throughout the combustion phase, while a 'bad' quality fuel shows a low initial rate of combustion p rio r to reaching maximum radiation level, being o f the same magni­ tude as fo r the good fuel, which is main­ tained very shortly (only during m illi­ seconds) and is follow ed by slow and marked after burning. Reference [ 19] illus­ trates the differences mentioned in the above. The differences are even more pro­ nounced under conditions o f lower tem perature and pressure, in o th e r words, they are dependent on the load. In some cases it may happen that it is impossible to achieve a proper ignition w ith a ’bad' fuel under low load conditions. Fuel analysis The traditional parameters defining igni­ tion performance o f distillate fuels, cetane number, calculated cetane index and diesel Index are o f uncertain relevance to residuel oil. SenW 55STE IA A R G A N G NR 12

Research w o rk carried o u t so fa r has indi­ cated, th a t various analysis data, giving m ore com plete in fo rm a tio n on th e chem i­ cal structu re o f th e fuel, c o rre la te w ith ignition and com bustion quality. For the tim e being, it seems, th a t a b e tte r classification o f heavy fuels can be obtained by analytical methods, such as:

- various gas chromatography techniques - gel permeation chromatography - high performance liquid chroma­ tography However, the investment cost and person­ nel skill, required to evaluate the informa­ tion, mitigate against th e ir use in practice. To overcome the draw-backs o f the more sophisticated methods, a m ethod suitable for practical use has been investigated. This method involves a recording o f rates o f change o f w eight o f a fuel sample during heating in an oxydising atmosphere. It is called the 'w eight distribution m ethod’. Reference [ 19] illustrates the results o f the method applied to a residual fuel giving no problems and a residual fuel that has caused severe engine damage. As indicated earlier, it seems, that the structure o f the hydrocarbon fuel mole­ cules is determ inent fo r the ignition quality of the fuel. Tests on laboratory engines and constant volume bomb test have indicated a fair relationship between the arom aticity o f the fuel and the ignition delay [19], [20], Arom aticity can be expressed either as carbon aromaticity o r as hydrogen aromaticity. The first one is the percentage of carbon atoms incorporated in aromatic rings, the second one is the percentage o f hydrogen atoms attached to aromatic rings. Because the aromaticity value is n ot readily available in practice, attempts have been made to correlate it w ith inspection prop­ erties o f the fuel, which are readily avail­ able. A good correlation was found be­ tween carbon aromaticity and a function o f density and viscosity. This correlation is referred to as the Calculated Carbon Arom aticity Index (CC AI). Reference [20] shows the relation between the aromatic­ ity and C CAI fo r different fuels; in this reference the relation between ignition delay and CCAI is also shown. Fuel tre a tm e n t Another aspect o f low quality residual fuels is the content o f impurities that can harm engine components, such as not emulsified w ater and catalytic fines, due to th e ir co r­ rosiveness o r abrasiveness. W ith straight run quality fuels the contaminants can be removed by the traditional onboard fuel treatm ent equipment. Difficulties arise when the fuel densities and specific weights increase to values, that can not be handled by this equipment w ith ­ out changes o r adjustments. Since the use SenW 55STE IA AR G AN G NR 12

o f residual fuel, practical experience has indicated, that fuel preparation is critical to the successful operation o f diesel engines. A number o f onboard fuel treatm ents are employed - filtration, centrifuging, emul­ sifying, homogenising - but none can be said to be capable o f handling all type of heavy fuels [21], [22], Filtration is now inadequate fo r really low quality heavy fuels and homogenising is not capable o f handling catalytic fines properly. Centrifuging is limited by the problems o f separating oil and w ater at high viscosities and densities (up to unity). Test bed ex­ periments and shipboard trials have shown, that w ater can be separated effectively from high density fuels by vacuum o r even by atmospheric flash evaporation (depend­ ing on the tem perature). However, if the fuel is contaminated w ith seawater, the salt w ill not be removed [21], Even fuel blending, previously regarded as a safe procedure, is now considered to be slightly risky because o f incompatability problems. Although fuel suppliers are very aware o f this problem, the problem may arise onboard when bunkering 'on top'. The manufacturers o f fuel treatm ent equipment have developed th e ir products w ith enhanced results, nevertheless the ultimate goal, a shipboard fuel treatm ent plant, that can handle the lowest and cheapest qualities o f heavy fuel oil which are commercially available w ith o u t in­ creasing the operating and investment cost disproportionately has not yet been attained. Although fo r obvious reasons fuel additives have been ignored by diesel users, they may provide some o f the answers to incom­ patibility o f w ater separation and to con­ trolling corrosive sodium and vanadium attack on engine components. A traditional reason fo r centrifuging is to remove water. In recent years extensive tests on testbed and at sea as well, have shown that provided the size o f w ater droplets in the fuel is sufficiently small, fo r example by homogenasion, w ater w ill not harm the engine. Experiments w ith w ater in fuel emulsion have confirmed, that not only deposits are softer but also, up to a maximum w ater percentage, which depends on the engine type and the load, an improving effect on ignition delay and the combustion is observed, resulting in low e r fuel consump­ tion under part load [23]. Under normal load conditions the effect is negligible fo r most engine types. Equipment to prepare stable emulsions based on various physical principles have been developed. F u tu re w o rk Although it is anticipated, that even at the end o f the century, there w ill be supplies o f residual fuel available, the quality may vary in many instances from the quality o f

straight run heavy fuel (e.g. visbroken residue and light and heavy cycle oils). Also o th e r coal derived 'oils' may pene­ trate the marine fuel oil m arket such as fo r instance Solvent Refined Coal (SRC), Shale Oil, Slurry Oils (coal-oil o r coal-water). These fuels w ill be acceptable to the ship­ ping industry as soon as they meet the following preliminary requirements: burn­ able in a diesel engine, low cost in relation to its energy content w ith o u t increasing first cost and maintenance cost dispropor­ tionately, onboard storage must not de­ stroy the economics of ship operation, safe under shipboard handling and storage con­ ditions, commercially available along the w orld trade routes. Diesel engine development has shown, that present day and future problems w ith the use o f refinery residues o r derived oils, as fuels, can be solved by cooperation be­ tween engine builders, fuel suppliers, fuel treatm ent equipment manufacturers and the operators. The engine builder and pre­ treatm ent equipment manufacturer are challenged to design systems (fuel heating, fuel injection, air cooling o r heating), that can be adjusted continuously to the fuel quality under varying load conditions. The fuel supplier should provide the neccesary data thereto. The operator should provide the information on the performance o f the engine and fuel auxiliary systems. O n many ships the engineer is challenged to operate an engine o f the past w ith the fuel of the future. Fundamental laboratory support, both theoretical and experimental, is necessary to attain solution w ithin accept­ able limits of tim e and investment. A U T O M A T IO N A N D R E S U L T IN G E F F E C T S In tro d uctio n Since the Japanese ship 'Kinkasan Maru’ w ent to sea in 1961, introduced by her builders as the first 'automated' ship, auto­ mation o f shipsystems has increased dramatically. Being envisioned by some as a cornucopia o f commercial blessings and the ultimate solution o f many problems and by others considered as Pandora’s Box o f evils, auto­ mation has proved to be neither o f these extremes. Reluctance of shipowners, due to lack o f experience w ith techniques un­ common onboard ships so far, such as hy­ draulics, pneumatics and in particular elec­ tronics has resulted in a slow start. H o w ­ ever, the advances made in comparable levels o f land based industries have gradual­ ly dissolved the suspicious view w ith re ­ gard to reliability and availability. The im portant reasons fo r which shipown­ ers have changed course are the greater economic return, the necessity to keep abreast o f advances in automation made by competitors, foreign o r domestic, the ever increasing com plexity o f the propulsion 241

and auxiliary machineries and systems and the critical shortage o f experienced skilled personnel. Present day technology is so developed, that a degree o f automation o f new build­ ings, depending on various factors, has be­ come common practice. In the earlier phases o f development, the precise meaning o f the w ord ’automation’ was not clearly defined. ’Mechanisation', 'rem ote co n tro l’ and ’automation’ were not strictly distinguished. Nowadays, automation is defined as a tech­ nique, that takes the place o f human func­ tions o f observation, e ffo rt and decision and controls the operation o f an equip­ ment o r system. ’Remote co n tro l’ is operation o f equip­ ment from a point far removed from the equipment; it does not imply that such equipment is automated. W ith rem ote control, complete manual operation can still exist. An equipment is defined to be ’mechanised’ if the physical task o f manual operation is taken over by a mechanism such as an electric- pneumatic- o r hydraulic m otor. However, if fo r instance a m o to r operated valve were part o f a feedback control sys­ tem, that controlled a flowrate, this would fall under the category o f ’autom ation’. According to these definitions a truly ’automated ship’ would have no crew whatsoever. O b je ctiv e The aim o f automation is to achieve a ship which can be operated at less cost than at present and be less subject to the increas­ ing operating cost; in o the r words: at the minimum cost per ton-mile. Shipping operation is very complex, be­ cause many factors such as capital cost, crew cost, maintenance and repair, routes, ports, cargoes, legal and political con­ siderations, technical and economical life and others, determ ine the economics.

fields. Especially in the electronic field o f missile and space industries impressive ad­ vances have been made. During the seven­ ties, reliability and maintainability en­ gineering (R&M) m ethodology have been introduced occasionally in naval ships. In commercial shipping formalized reliabil­ ity and maintainability engineering can be characterized as e xploratory at this time. The present day problem in the application of R&M is mainly lack o f specified com po­ nent reliability and maintainability. This ap­ plies in particular to sensors which still appear to be sources fo r erroneous in­ formation. The component R&M data can be obtained from data banks. Electronic components data are today sufficiently available from data banks. Data concerning mechanical equipment and components are in­ creasingly obtained from shipowners-, manufacturers and classification society in­ form ation systems. The availability o f sufficient data enables the designer to calculate the reliability and maintainability and consequently the availability o f the equipment and systems. Also the failure rate as well as the need fo r preventive and corrective maintenance can be predicted. Further, weak points and strong links can be identified and thereby the investment concentrated on the weak links and over­ design avoided. Weak links can be analyzed in o rd e r to b etter satisfy specified operational availability requirements and obtain low maintenance cost. Although it is not yet possible, it may ultimately be possible fo r the shipowner to specify and the shipbuilder to guarantee the reliability and maintainability char­ acteristics o f the machinery. Reliability assessment techniques have been developed in various fields o f techno­ logy. They can be either qualitative o r quantitative.

R eliab ility and M a in ta in a b ility (R & M ) For the subject under consideration this implies among others, that one o f the essential requirements fo r the automatic controls, as fo r all o th e r marine equipment, is reliability and maintainability. Reliability is usually defined as 'the probability that a component o r a system w ill perform its required function w ith o u t failure during a specified tim e interval’. It can be expressed as 'Mean Time Between Failure (MTBF)’. Maintainability is defined as the mean tim e to repair a component o r a system, which can be expressed as ’Mean Time To Repair (M TTR)’. These tw o aspects o f marine engineering in general and o f automation in particular have been subjects o f research and de­ velopment, both theoretical and ex­ perimental, since 1950 in non-marine

Usual methods o f analysis are: - availability and reliability analysis - fault tree analysis - failure mode and effect analysis (FMEA). In availability and reliability analysis as well as in fault tree analysis mathematical mod­ els are used. These models are system oriented and suitable fo r qualitative and quantitative analysis. The fault tree analysis is extensively used in risk studies w ith the aim o f tracing the sequence o f events which could lead to a major hazard. The failure mode and effect analysis is con­ cerned w ith identifying component failure modes and th e ir effects on system failure. The objective is to identify predictable failure modes, to avoid as many o f these as possible and to calculate the resulting need fo r maintenance, occasionally over the life time.

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A d escription o f FMEA is given in re f [24] It involves briefly: - the equipm ent is divided in sub-assem­ blies o r com p o n e n t parts - each m ode o f failure is classified, accord­ ing to th e e ffe ct on th e system - a p p ro p ria te ly stressed failure rates are applied and summated fo r each class of failure.

D a ta acquisition and use The key to the successful developm ent of re lia b ility engineering is reliable data. In setting up a program to c o lle c t system and equipm ent data, th e objectives should be specified such as: - to p ro vid e su p p o rt fo r operations and maintenance management - to p ro vid e s u p p o rt fo r an engineering management in guiding p ro d u c t design. The data re p o rtin g system must be based on the acquisition system. A lso failure clas­ sification is an im p o rta n t data element. Failure classification is e.g.: - P rim ary failure - Secondary failure - Marginal failure - Cascade failure - C atastrophic failure.

F u tu re research w o rk The m arine engineer is challenged to find ways and means fo r the im plem entation of re lia b ility and m aintainability m ethodology in th e design w o rk and o p e ra tio n o f plants used in sea tra n s p o rta tio n and sea e xploita­ tion. For th a t purpose various studies and de­ velopm ents have to be carried o u t, such as: - models fo r physical and functional break do w n o f a system - models fo r th e quantified p re d ictio n of in h e re n t availability - models to calculate th e economically defined qua n tity o f spares - study and specify th e q u antity and quality o f the data to p re d ic t equipm ent re­ lia b ility - study suitable use o f failure m ode and effects analysis as w e ll as fault tree analysis - study a suitable use o f life cycle cost in the design stage.

Final re m a rk s In various co u n trie s all o v e r th e w orld , research associations, classification societies, universities and companies are involved in re lia b ility and maintenance pro je cts o f seagoing structures. The tendency o f c re w num bers to de­ crease has given stro n g m om entum to the in tro d u c tio n o f this branch o f m arine en­ gineering.

M aintenance T h ro u g h o u t th e past decades th e reduc­ tio n in crew num bers, as a result o f the in tro d u c tio n o f re m o te c o n tro l and auto­

SenW 55STE IA A R G A N G NR 12

mation have intensified the discussion on shipboard maintenance. From the vast number o f publications and papers presented at numerous symposia on the subject, it is evident, that many maintenance procedures have been de­ veloped and introduced. Also it has become clear, that the effective­ ness of a maintenance procedure largely depends on many factors which may vary from company to company, from trade to trade, from ship type to ship type, from machinery to machinery and last but not least from number and skill o f staff both onboard and ashore. Decisive fo r mainte­ nance are prim arily safety, as reflected in IMO resolutions, national legislation and rules o f classification societies and economy. Maintenance procedures can be distin­ guished basically as corrective mainte­ nance, which is repair o f failed components and preventive maintenance, which can be scheduled o r condition based. Beside factors mentioned in the above, the maintenance procedure to be applied to a sytem o r a component also depends on the important factor: experience, in the sense o f need fo r maintenance. This aspect is highly influenced by make in term s o f de­ sign and material and service conditions in terms o f load, mechanical as well as th e r­ mal, and environmental conditions, such as vibrations and shock, heat radiation and moisture. In the authors’ view it is impossible to set up a maintenance procedure in the design stage o f the machinery, that w ill be effec­ tive throughout the economical life tim e o f the ship. In other words, procedures have to be adapted continuously o r at intervals accord­ ing to experience obtained in the ships’ life. Also the ever decreasing complement o f ships in service and in particular on new buildings and also the shorter turn-around times in ports w ill require continuous de­ velopment o f maintenance philosophies and consequently maintenance proce­ dures by owners, legislative bodies and classification societies. Their is no doubt, that crews have to be provided w ith modern decisionmaking computerized ’tools’ in o rd e r to m eet the objectives o f the maintenance procedure fo r th eir ships. This decision-making to o l should be rapidly adjustable to changes in ships’ services and trade at short notice. Such computerized tools are fo r example: - condition m onitoring systems - expert diagnostic systems - data and data processing systems - feedback between ship and shore based information systems - fast communication systems. These systems have fo r many years been introduced in machineries and installations SenW 55STE IA AR G AN G NR 12

w ith poor o r no accessibility under operat­ ing conditions, that cannot be interrupted fo r safety reasons o r catastrophic conse­ quences, such as fo r example, air craft, space craft and nuclear systems. Also w here accessibility o f the component to be maintained requires removal and/or dismantling o f many o the r components requiring less o r no maintenance at all, these tools can be used successfully. It should be emphasized, that these tools do not stand on th e ir own, nor do they solve every maintenance problem. Once a proper maintenance philosophy has been set up, they can be used separately o r in a variety o f com puter connected combina­ tions. C o nd itio n m o n ito rin g Those components, that w ill be condition based maintained have to be m onitored in some way o r another. Although sometimes visual inspections at regular intervals during down tim e may suffice, mostly a more sophisticated tech­ nique is necessary. The generally accepted basis o f condition m onitoring is the deviation concept. In this concept the criteria to assess the condition o f a component, machinery, system or equipment, is the deviation between a ser­ vice parameter and a reference parameter. The service parameter is either measured directly o r obtained, fo r example by calculation from measured performance data. Service parameters are fo r example pistonring w ear o r cylinder wall tem perature in a diesel engine, w ear o r tem perature o f a bearing, vibration level o r noise o f a machinery, content o f metal particles in lubricating oil, thermal o r thermal dynamic efficiencies o f boilers and turbines o r inter­ nal combustion engines, heat transfer coefficients in coolers o r heaters, cleaning efficiency in treatm ent equipment etc. The parameters to be analyzed depend natural­ ly upon the equipment to be maintained. In most cases they are selected by both manu­ facturers and users because they have the knowledge o f the characteristics o f the product and experience in operation re­ spectively. In the assessment o f the service para­ meters, it should be recognized, that they may also be dependent on o r even be a function o f the service and/or environmen­ tal condition. This applies, fo r instance, in particular to the efficiency o f tu rb o machineries such as steam o r gas turbines and tu rb o compressors, which are strongly dependent on the load. The thermodyna­ mic efficiency o f a steam plant is highly determined by the environmental condi­ tions such as air- and seawater tempera­ ture. Also the condition o f other components o f the plant may influence the behaviour and thus the service parameters o f the compo­

nent under consideration. These effects should be compensated in ord er to obtain comparable condition parameters w ith acceptable accuracy. For that purpose, a mathematical model is generally used to calculate the parameter fo r the ’as new’ condition o f the compo­ nent operating under the same load- and environmental conditions. [25], Future condition parameters can be evalu­ ated through trend analysis. This is achieved by storing the condition deviation data from consecutive condition determinations and therefrom calculating a trend curve. An estimation o f the future condition is achieved by extrapolation. By setting a prefixed lim it, the actual tim e fo r maintenance can be predicted. The w o rk involved in the elaboration of the parameters and the analysis can be done through computers onboard o r ashore. It goes w ith o u t saying, that the design o f a preventive maintenance system based on condition m onitoring should have a re­ liability and availability o f a higher order than that o f the equipment to be main­ tained. Unreliable data o r a failing condi­ tion m onitoring system is worse than no system at all. The designer should be aware o f a satisfactory compromise between simplicity, to meet the requirem ent of reliability and availability and com plexity to meet the requirem ent o f quality and quantity o f data, in a context o f to ta l cost effectiveness attractive fo r the ship-own­ ers. C oncluding re m a rk s It is the authors’ firm belief, that preventive maintenance through cost effective condi­ tion monitoring, w ill reduce ship operating costs and thus increase earnings through b e tte r efficiency and reduced off-hire, to the benefit o f all those concerned: shipbuild­ ers, equipment manufacturers, owners and crews. It is a challenge to the researchers in the field o f reliability and availability: - to set up the maintenance philosophy - to select the condition parameters - to select the measuring locations - to select the measuring and m onitoring equipment - to develop com puter soft ware w ith the aim o f optimising the maintenance strategy and -system fo r the ship and her service under consideration. M anning Closely related to the subjects dealt w ith in the previous paragraphs is the subject o f ships’ crews. However, other and various items also influence the number and composition o f the crew, such as availability, capability, costs, social demands. For a particular ship, factors like voyagedistance, number o f ports on the route and hazardous naviga­ tio n areas have to be taken into account. 243

There is no doubt, that the tendency to reduce ships’ crews w ill continue, p ro ­ vided that the crew is well organized, edu­ cated and trained on a more o r less con­ tinuous basts, in ord er to keep up w ith the technical development. Semi- and at lon­ ger notice, fully integrated crew w ill be necessary fo r continuing crew reduction. Researches all over the w orld indicate, that reduction o f crew numbers under 15 in the forseeable future and even below 10 in the next century may be realised. Even discussions about ships, unmanned o r rem ote controlled during the ocean pas­ sage are being held at various occasions. [27], This idea can be achieved w ith current technology o f availability and reliability as w ell as maintainability has reached the re­ quired level w ith o u t disproportionate first costs. It seems, that the economic limits o f speci­ fic figures such as fuel consumption, weight and volume have almost been reached and thus suppliers have to focus th e ir develop­ ment efforts on the above mentioned aspects. Undoubtly social problems w ill arise, however, also undoubtly solution w ill be found in discussions and negotiations be­ tween the parties involved, shipowners, labour unions and government authorities. Education, tra in in g and safety These aspects o f ship operation are dealt w ith under the same heading because they are very closely related. A t various symposia, held to discuss means o f reducing the risk o f accidents at sea, the most im portant single factor was consid­ ered to be human e rro r. Analysis o f ship accidents have shown a clear evidence that human fallibility is by far the most im por­ tant cause (85 %). The accidents attributable to human e rro r mainly derive from tw o major sources: - Insufficient knowledge o r inability to use the machinery and equipment to oper­ ate a ship safely. - Failure to operate a ship, supposed to be adequately equipped, safely despite assumed proper education and sufficient experience. The author wants to emphasize, that in his view the te rm ’human e rro r’ is not only applicable to the operator, the man onboard, but also and not seldom to the designer. This applies in particular w ith regard to the safety systems. O ften the human e rro r is built into the system itself. The designer and all others who consid­ ered the system to be infallible did not realize, that the operators w ho have to obey the system are part o f that system. This means, that an essential part o f the system is the human being showing a fallible behaviour, that is characteristic fo r a hu­ man being. 244

Typical examples o f human qualities o f importance fo r operator tasks are varia­ tions in his pow er o f perception and mem­ ory: also his sensitivity to boredom and automatism, such as an action, that has been taken, regularly many times, w ill be fo rg o t­ ten at a tim e when it should not have been forgotten. Once again, the designer o f automatic and in particular safety systems should never forget, that operators show failures reg­ ularly, albeit seldom, which is a characteris­ tic o f human beings. As shipboard equipment becomes more reliable and automation, including com­ puterized fault finding and condition monitoring, which includes diagnosis and trend analysis, becomes increasingly com­ mon practice, users have to make the im­ portant choice between a vessel minimum manned by a class o f engineers, whose bases source o f information is limited to the com puter displays, which could lead to a crew o f legless theoreticians unable to cope w ith a practical problem, o r a vessel minimum manned w ith a class o f engineers educated and trained to co rrect faults manually, using reliable computerized sys­ tems as tool. As long as robots have not been developed to c o rre ct faults, the first mentioned choice should not be made. For many years to come, ships should be manned w ith the minimum crew educated to operate a plant in the widest sense, using computerized equipment w ith a higher degree o f reliability than the plant it has to control and supervise and trained on a regular tim e basis. T o some e xtent the comparison w ith the air- and spacecraft and also nuclear industry suggests itself. Integrated ship simulators are therefore necessary fo r training purposes. The simu­ lator should dynamically model all the ships’ functions, navigation manoeuvring, propulsion- and auxiliary machinery and cargo handling. For example engineers can be trained ashore in starting up from dead cold condi­ tion as well as in recovering after a malfunc­ tion resulting in complete shut down and also at any tim e and at any service condition failures, malfunctions and o th e r events, which can be expected in existing plant operating conditions can be introduced by the instructor and corrected by the trainee. As far as the engineering aspect is concerned the educational and training courses should be aimed at: - obtaining confidence in handling rem ote controlled machinery through ’handson’ operation - handling extensive failures, which are e ither dangerous, difficult o r exceeding­ ly costly to enact onboard ship - improving operating practice w ith re­ spect to saving o f fuel. T o emphasize machinery safety, courses should impart procedures to be follow ed

fo r safe operations in various plant evolu tions and fault diagnosis, particularly in thcase o f malfunctions, which do not ofte occur. The energy saving part o f the course shoul deal w ith subjects such as: - heat balance calculations to establis, component - and overall plant efficiency as well as, detection o f component de terioration and th e ir causes - demonstration o f the effect o f varying environmental parameters like air- anc sea w ater tem perature and componeni deterioration caused by fouling - study slowdown operations and demon­ strate conditions which require tuning o f the plant. In the authors’ institute various types oj ships simulators have been designed and developed since the early seventies. Both experienced engineers and pilots from all over the w o rld and cadets from the national nautical schools have been trained and educated. The design and building o f a national multi­ purpose, fully integrated, sophisticated simulator is in the preliminary phase. It is the authors’ firm belief, that ships o f the near future w ill be manned by the minimum number possible o f highly educated, and at regular tim e intervals, well trained, ’inte­ grated’ engineers. In this, simulators, incorporating all ships functions w ill play an indispensable role. The minimum crew w ill depend on ship and machinery type and size, trade, legislation as well as social and economical considera­ tions. Although, fo r the o w ner the fully auto­ mated unmanned ship must be a desirable objective and although technically feasible, the foreseeable outcome in term s o f de­ cades w ill be as mentioned in the above. FUTURE D EVELO PM EN TS Intro d uctio n H istory has shown, that the future as a result o f human activity has never been accurately predictable from the past and present time. Nevertheless the past and the present are the basis fo r vision and conditional fore­ casting, taking into account that changes in the factors influencing the development may be rapid, unpredictable and some­ times o f surprising variety. This is illus­ trated clearly by comparing forecasts pub­ lished in journals by learned Institutions of high standard o r presented at symposia by w ell known learned experts, w ith present day state o f technology. However, it may be taken fo r sure that progress in marine engineering w ill continue w orldw ide. Big steps forw ard and long steady continuing development w ill be interrupted by small­ er steps backward and periods o f steady state. In the commercial shipping industry SenW 55STE IA A R G A N G NR 12

the development process is, to the ^greatest extent controlled by economic ■factors, which in tu rn are dependent on social and political factors, and less by ^technical development. In the following paragraphs a brief survey of the authors’ view on development o f the main systems in the coming decades w ill be given. P rim e m o v e r Except fo r special ship types, trading on special routes, such as coal carriers, steam turbine propulsion w ill decrease and even­ tually die out completely, even fo r passen­ ger cruise ships. The rapid, even by experts unexpected development o f the slowspeed, tw o stroke, turbocharged, diesel engine has given the lead to that prime mover, both in specific pow er and fuel consumption. The various development objectives o f the diesel engine since its invention and very first trials such as, residual fuel burning in the late forties, exhaust gas turbine driven supercharging in the early fifties, pow er density in the sixties and early seventies, lower consumption o f poor quality fuels in the seventies and eighties, have resulted in a relatively simple engine w ith a th erm o ­ dynamic efficiency, that has never been equaled in the history by any o th e r prime mover type. Slightly low e r fuel consumption may be expected, however, thermodynamic con­ sideration, show that the ultimate lowest specific fuel consumption w ill be obtained w ithin five to ten years. This w ill be about 110 gr/BHPH corresponding to a th erm o ­ dynamic efficiency o f about 60 % . Future development w o rk w ill be aimed at reliability, reduced maintenance and capability to burn the cheapest fuel avail­ able on the market. Six months o f mainte­ nance free running seems reasonable w ith ­ in five to ten years. The four stroke, medium speed, tru n k pis­ ton engine w ill fo llo w this trend, gradually, approaching the achievements o f its low speed counter part. Application o f this machinery type depends strongly on logis­ tic considerations like ships type, sailing schedule, space and weight, manoeuvrabil­ ity and economical aspects, like first cost, maintenance and repair, availability by re­ dundancy, number and cost o f required spare parts etc. W aste h eat recovery Further lowering o f the overall fuel con­ sumption can be obtained by utilizing the heat present in the exhaust gas. It can be shown theoretically that fu rthe r refinement o f the thermodynamic cycle, e.g. by reduced cooling o f the walls sur­ rounding the combustion chamber, w ill not result in significant low er fuel con­ sumption per brake horse pow er w ith o u t increasing first cost disproportionately. SenW 55STE IA AR G AN G NR 12

The additional heat in the combustion gas resulting from reduced heat loss using high temperature resistant materials like cera­ mics, can be converted into useful pow er in an exhaust gas turbine connected to the crankshaft and/or used fo r raising steam in an exhaust gas boiler, which heat content can be converted into shaftpower in a steam turbine. The surplus exhaust gas energy, which is the heat not required to drive the tu r­ bocharger, can also be used to raise auxil­ iary pow er by gas- o r steamturbine drive of an electrical pow er generator. Further improvement o f the overall effi­ ciency can be achieved by combining the mainpower system w ith a low tempera­ ture Rankine bottom ing cycle. However, although technically possible and economically feasible from a fuel con­ sumption point o f view, the overall econo­ mic feasibility seems to be doubtful due to such factors as capital cost, maintenance cost, com plexity o f the control systems, ergonomic considerations etc. Such complex systems take away one of the attractive features o f the diesel engine prime power, which is its simplicity. Therefore although various sophisticated waste heat recovery energy saving systems have theoretically been developed, the practical application is progressing slowly. So far it is restricted to a relatively small number o f new buildings. C O N C L U S IO N S There is no doubt; that future develop­ ments both short term and long term as well; w ill strongly depend on the in­ ternational economics. In the shipping industry the m arket pull has always dominated the technological push. The reason why is that the shipowners’ product is ton-m ile and not the ship as a technical object. There is obviously no reason fo r this pattern to change. For decades in the next century the p ro ­ pulsion and auxiliary machinery w ill be diesel engines capable o f burning properly treated low quality fossile fuels o r mixtures w ith an efficiency increasing to 60 %. In the long run even m ore if high tempera­ ture resistant non metal materials like ceramics, are used to prevent heat loss through the combustion chamber walls. The ultimate goal could be a fully heat insulated uncooled engine, burning the cheapest fuel available to produce shaft horse pow er and high tem perature ex­ haust gas, whose heat content is converted into main o r auxiliary mechanical power. The development o f the high tem perature compound engine, w ill take a long time. The spin-off o f developments in high tem perature technology in o the r fields w ill play an im portant role. In the short term , development w ill be concentrated on reliability and main­ tainability and thus availability. Six months

operation w itho ut any maintenance, pre­ ventive o r by repair seems to be an achiev­ able goal w ith o u t disproportional conces­ sions to safety. Education and training w ill be focussed on a fully integrated crew, steadily decreasing in number, being capable o f operating the fully automated and rem ote controlled propulsion machinery and auxiliaries by means o f e xpert com puter systems. Brainstorming about unmanned ships is in­ creasing in panel sessions at conferences and symposia all over the w orld. [27] Opinions concerning crew reduction diverge. One opinion says: it is probable that further crew reduction w ill not be obtained by increasing automation because the result w ill be more com plexity and thus vulnerability o f the plant. If crew reduction is obtained, the crew w ill consist o f highly educated and continuously trained experts and thus increasing crew cost. It seems to be more profitable to direct research and development towards simplicity and reliability, starting from eco­ nomic and acceptable crew cost. The objective should be simple reliable machinery equipped w ith a minimum o f self controlling systems. The opposite view is a development tendency comparable w ith the develop­ ment in the chemical industry. The philosophy in this field is that the reliability o f computerized systems should be at least exceed that o f the mechanical parts by one order. This would result in an overall reliability that is at least equal and probably greater despite increased com­ plexity. Expert knowledge and know -how o f sys­ tems and components is available onboard in easily accessible com puter software. More detailed information knowledge and know -how is easily accessible by modern communication in shore based systems and experts. Highly educated and experienced en­ gineers are ashore and w ill be able to render services to many ships. The shipboard engineer w ill become a technician w ith management- and decision capabilities, particularly in crisis situations. As indicated earlier, history has shown that the economy o f shipping w ill be the deci­ sive factor in ship machinery development. F U T U R E B A S IC R E S E A R C H In the authors’ view the main topics o f the research and development in marine en­ gineering w ill be focussed on: - system analysis in the design stage - reliability and maintainability o f mainand auxiliary machinery and systems in­ cluding reliability prediction in the early design stage - computerized automation capable to in­ dicate failure o r malfunction causes, sub­ sequent malfunctions, diagnosis, fault 245

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management and corrections to recov­ er normal o r safe operating conditions (expert systems) condition m onitoring to supervise the state o f vital machinery components and operating conditions as well, in o rd er to rationalize preventive maintenance simplification o f mechanical systems and components test methods o f components and sys­ tems under simulated operating and en­ vironmental conditions education and training at regular in te r­ vals o f fully integrated engineers (nauti­ cal, technical as w ell as management) onboard and advisory e xpe rt engineers ashore. communication systems w ith shore based support stations.

Final re m a rk s Because o f its com plexity Marine en­ gineering w ill always be a field o f technolo­ gy where perfection is illusory. T o researchers and designers the optimal compromise between technical feasibility, economical, social- and political aspects w ill be the everlasting challenge, that gives the satisfaction o f th e ir profession. A ck n o w le d g e m en t The author acknowledges the researchand development w o rk on the subjects dealt w ith in this paper, by research insti­ tutes o f T N O , Technical universities and manufacturers, initiated and co-ordinated by the form er Netherlands Ship Research C entre T N O . Reference is made to the w o rk carried out by research institutions in o the r countries, co-operating in the ’International C o ­ operation o f Ship Research’ (ICSR). Regarding the subjects 'V ibration' and 'Re­ liability and Maintainability’ the summariz­ ing w o rk o f the relevant Technical C om ­ mittees o f the 'International Co-operation on Marine Engineering Systems’ (ICMES) is also acknowledged. The author thanks the Organization fo r Applied Scientific Research fo r permission to publish this paper.

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References 1. Nestoarides, E. J. (ed): 'B.I.C.E.R.A.: A Handbook on Torsional Vibration’. Cam­ bridge University Press 2. Ker Wilson, W.: 'Practical Solution of Torsional Vibration Problems', 3rd ed. Chapman & Hall, London 3. Sarsten, A., Holth, T. and 0vreba, A.: 'A Method fo r Direct Solution of SteadyState Forced Vibration of Lineair Systems’. ASME-paper 73-DGP-I2 4. Langbaile, M.: 'Investigations into the Stressing o f Crankshafts fo r Large Diesel Engines'. DnV publications No. 57 5. Draminsky, P.: 'Crankshaft Damping'. Pro­ ceedings o f the Institute o f Mechanical En­ gineers 6. Draminsky, P.: 'Extended Treatment of Secondary Resonance'. Transactions o f the Institute o f Marine Engineers and Naval Architects 7. Krogh, F. and Larsen, O.C.: 'Numerical Simulation Models and Stability Criteria for Coupled Multi-Engine Installations. Torsional Vibration Analysis. Proceedings o f ISME-Conference Tokyo 8. D ort, D. van and Visser, N. J.: 'Crankshaft Coupled Free Torsional-Axial Vibrations of a Ship’s Propulsion System’. Report no. 39M, Netherlands Ship Research Centre TNO . 9. Visser, N. J.: The Axial Stiffness o f Marine Diesel Engine Crankshafts’, Part I. 'Com­ parison Between the Results of Full Scale Measurements and those o f Calculations According to Published Formulae’. Report no I02M, Netherlands Ship Research Cen­ tre T N O 10. Linden, C. A. M. van der: 'The axial Stiffness of Marine Diesel Engine Crankshafts', Part II. ’Theory and Results of Scale Model Measurements and Comparison w ith Pub­ lished Formulae’. Report no I03M, Netherlands Ship Research Centre T N O 11. Linden, C. A. M. van der, ’t Hart, H. H. and Dolfin, E. R 'Torsional-Axial Vibrations o f a Ship’s Propulsion System’, Part I. ’Compar­ ative Investigation o f Calculated and Mea­ sured Torsional-Axial Vibrations in the Shafting of a D ry Cargo Motorship’. Report no. 116M, Netherlands Ship Research Cen­ tre T N O 12. Gent, W . van and Hylarides, S.: 'TorsionalAxial Vibrations o f a Ship's Propulsion Sys­ tem ’, Part II. 'Theoretical Analysis of the Axial Stiffness o f the Shaft Support at the Thrustblock Location’. Report no. I 32M, Netherlands Ship Research Centre T N O 13. Linden, C. A. M. van der: 'Torsional-Axial Vibrations of a Ship’s Propulsion System’,

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27.

Part III. 'Comparative Investigation of Calculated and Measured Torsional-Axial Vibrations in the Propulsion System of a Tanker'. Report no 137M, Netherlands Ship Research Centre T N O Wereldsma, R.: 'Experiments on Vibrating Propeller-models’. Report no. 70M, Netherlands Ship Research Centre TN O Hylarides, S.: 'Transverse Vibrations of Ship’s Propulsion Systems', Part I. 'Theoretical Analysis'. Report no. I97M, Netherlands Ship Research Centre T N O Wevers, L. J.: Transverse Vibrations of Ship's Propulsion Systems, Part II. ’Ex­ perimental Analysis'. Report no. 203M, Netherlands Ship Research Centre TN O Leemans, M. and Roode, F.: 'Vibration Analysis of a Rotating Propeller Shaft in a Rubber Stern Tube Bearing’. Proceedings of ICMES ’84 Symposium ICMES-TC6: 'Shafting System Dynamics' Status Report Fiskaa, G. and Bergh, O.: ’Ignition and Com­ bustion Properties o f Heavy and Synthetic Fuels in Diesel Engines’. Proceedings ICMES-’84 Symposium Zeelenberg, A. P., Fijn van Draat, H. J., Barker, H. L.: ’The Ignition Performance of Fuel Oils in Marine Diesel Engines’. Pro­ ceedings CIMAC-’83 Symposium Mooy, A. de et al: 'Residual Fuel Treat on Board Ships’, Part I, II and III. Reports no. 92M, 95M and I29M, Netherlands Ship Research Centre T N O Vincent, M. R. and Harrison, J. W.: 'Review of Shipboard Fuel O il Treatment’. Transac­ tions of the Symposium on Future Alterna­ tives fo r Marine Propulsion. IME 1981, paper C80 Thompson, R. V., Thorp, I., Armstrong, G. and Katsoulakos, P.: The Burning of Emulsified Fuels in Diesel Engines'. Trans­ actions of the Symposium on Future Alternatives fo r Marine Propulsion. IME 1981, paper C8I Dellgren, N. et al: 'Reliability and Safety in the Marine Industry’, Status Report of ICMES-Technical Committee I Venton, A. O. F. and Parkes, D.: ’A British View of the Condition Monitoring Aspects of Preventive Maintenance’. Proceedings of the ICMES Conference on Condition Monitoring and Preventive Maintenance Jong, W . de: 'Condition Monitoring, Trend Analysis and Maintenance Prediction for Ship’s Machinery’. Report no. I90M, Netherlands Research Centre T N O Choa, F. S. B.: T h e Technical O utlook of Future Shipping'. Proceedings ICMES ’84 Symposium

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HOE MINDER LASSEN, HOE BETER DE PIJP. Seton fabriceert enkel en alleen pijpleidingen. Volgens ’t Prefab-systeem. Deze specialisatie is onze kracht. Het resultaat is dat alle pijpen van Seton al volledig afgelast (en zelfs met de juiste oppervlaktebehandeling) maatklaar naar het werk gaan. Dat komt de kwaliteit van de installatie ten goede. Verder scheelt het een hoop heen-en-weer gesjouw. Dus tijd. Seton is erbij. Vanaf het eerste ontwerp tot en met de komplete installering.

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DEVELOPMENT OF A NEW COMPUTER-AIDED SYSTEM FOR THE DESIGN OF SHIPS***

by: A. C. W. J. Oomen* and P. van Oossanen** ABSTRACT In this paper a description is given o f a new computer-aided system called HOSDES fo r the conceptual design o f ships. This system is being developed by M A R IN w ith financial support from the Royal Netherlands Navy, the Royal Shipyard ’De Schelde’ and the Netherlands Naval Ship Design Bureaus. This system has some unique features w ith respect to the software implemented in the user-interface system, allowing fo r true m ulti­ tasking capabilities and advanced data communication. A n integrated relational database system (MIMER) has been adopted to allow for an efficient manipulation o f data. A special system management subsystem has been incorporated fo r the purpose o f managing projects and users, and to introduce levels o f p rio rity and confidentiality in accessing and manipulating data. A special design-guidance subsystem has been included fo r providing special assist tools to the user. Some o f the technical application programs developed at M AR IN in recent years have been incorporated in the system. For preliminary design purposes the designer/user has available different programs fo r hull design, resistance and propulsion calculations, seakeeping and manoeuvring calculations, subdivision and superstructure design, mass calculations, hydrostatics and stability, etc. I. IN T R O D U C T IO N In the preliminary design stage it is im por­ tant to be able to quickly and systematically determine the influence o f hull geometry, propulsion configuration and many other design parameters on ship performance. W ith o u t the use o f the com puter it is often not possible to define the best suitable hull dimensions and hull form from , e.g. a com­ bined powering, seakeeping, manoeuvring and cost point-of-view . Furtherm ore, it is often not even possible to carry o u t this task in using only batchoriented com puter programs. The tim e is then usually to o limited to ensure an o p ti­ mum choice o f design parameters. An inte­ grated set o f application programs is then clearly required, integrated in such a way that a minimum amount o f tim e is spent in inputting and manipulating data between the designer and the various programs. The problem o f ensuring that the finallydesigned ship represents an optim um for the set design requirements is in most cases more im portant in naval ship design than in any o the r design case. The cost o f building a naval combatant is considerably higher than fo r any o th e r type o f vessel. This is mainly due to the extrem e costs involved w ith the acquisition o f the weapon and * Technical project leader HOSDES system, Design Research Department, Maritime Research Institute Netherlands (M ARIN) * * Overall project leader HOSDES sys­ tem, Head Design Research Departm ent, Maritime Research Institute Netherlands (M ARIN) * * * Paper presented at the 6th W EM T symposium, Travemünde, W . Germany; 2-5 June 1987; organized by Schiffbautech­ nische Gesellschaft. 248

sensor systems that these ships carry. If, therefore, a naval ship does not m eet its operational requirements in the best possi­ ble way, this is more serious than fo r a merchant ship. O n the basis o f these considerations, the M aritime Research Institute Netherlands (M ARIN) decided in 1983 to design and build an advanced computer-aided design system fo r the conceptual design o f ships. In the first instance this system is to be realized fo r naval combatants o f the frigate-destroyer type because o f the active

role MARIN plays in the conceptual design o f these ships fo r the Royal Netherlands Navy (R.NI.N) and o the r navies. A fte r definition o f a 5-year developmental program, MARIN obtained about 69% o f the initially-required budget of Hfl. 6,100,000,- from the Netherlands Government (59% ) and from the Royal Shipyard ’De Schelde' (KMS) and the Netherlands Naval Ship Design Bureaus (Nevesbu). The funds obtained from the Netherlands G overnm ent are in the form of a non-interest bearing loan, to be repaid

Fig. I. Design Spiral according to Buxton (1971)

EC O N O M IC

STRENGTH

SenW 55ST IA AR G AN G NR 12

Schematically, the design process on a computer can be represented as has been done in Figure 2, in which three basic elements are identified as follows: - the designer o r user o f the system; - problem -oriented sets o f application programs; - a database.

from royalties obtained from the sale and use o f the system. The total project, as presently defined, is divided into tw o parts. The first part has already resulted in software Release I (in April 1987) and encompasses the total system required p rio r to the design o f the three-dimensional hull form . Software Re­ lease 2, due fo r completion in August 1988, encompasses the preliminary design phase involving the three-dimensional hull form and basic superstructure and internal sub­ division aspects. This paper describes the design and de­ velopment o f this new system fo r the con­ ceptual design o f naval ships, later to be adapted fo r o the r classes o f vessels. This design system has been given the name HOSDES, a Dutch abbreviation.

In this design representation an executive system is required to allow user-friendly communication w ith data files and p ro ­ grams. Until 1983, com puter facilities at MARIN w ere used to perform individual calcula­ tions on a per-parameter basis. Although a complete design process can be obtained by ’chaining’ these programs, this is prac­ tically very costly and time-consuming due to the complex interface problems be­ tween the various programs since these programs w ere developed as stand-alone programs w ith th e ir own data files and user-interface.

2. B A S IC C O N S ID E R A T IO N S In the preliminary design stage, no general­ ly-accepted sequential approach exists. In­ evitably, however, the adopted process encompasses making a large number o f decisions, w ith each decision o r choice greatly affecting the next phase of the design. The adopted process is often re­ peated w ith a greater degree o f accuracy. It has been presented by Buxton ( 19 7 1) as a spiral, shown in Figure I . Translating this process into a computerenvironment requires a com puter-tool to facilitate each decision. Alternatively, if the designer does n ot w ant to rely on the computer fo r a particular decision o r wants to overrule the com puter w ith respect to a particular choice, his input o f a specific value fo r a design variable must not lead to an inconsistency in the data flow.

HOSDES was also designed as a solution to this problem. Its use w ill allow the interfac­ ing o f all required application programs, both existing and those yet to be de­ veloped. Also, the system w ill allow easy access to each and everyone o f these pro­ grams in a uniform manner by means o f a common user-interface. To avoid repeat­ ed inputting in using these different p ro ­ grams it was decided to create one inte­ grated and consistent database. To enable future addition o f application programs, the system was designed as an open-ended system w ith advanced and re­ fined software tools to allow a Systems

Fig. 2. The Basis Principle o f a C om puter-Aided Design System as used in HOSDES

DESIGN F I L E S ( DB)

APPLICATION PROGRAMS

Manager to quickly interface such pro­ grams. In the Netherlands, the HOSDES system is now being used by R.NI.N., KMS, Nevesbu and MARIN fo r preliminary design. A t MARIN the system is also used fo r running individual application programs because o f the ease w ith which this is done once the ship’s geometry has been established. The system therefore has to be true m ulti­ tasking, allowing different users to access data and application programs whenever they wish, even to the point o f different users accessing the same components o f the system simultaneously. 3. S Y S T E M D E S IG N The objectives o f the HOSDES system, as described in the previous sections, have been translated into a design process which provides five basic capabilities to the user. Before describing these in more detail, it is well to recall that this user may be either an interactive user, sitting at a terminal, or a programmer w ritin g application programs (A/P) to run w ithin the HOSDES environ­ ment, o r the System Manager w ho takes care o f the maintenance and consistency o f the environment (see Figure 3).

Fig. 3. Schematic Representation o f D if­ ferent 'Users' o f the HOSDES System The five capabilities provided by HOSDES are the following; 3.1 T h e U s e r-in te rfac e This consists of: • a menu-oriented command language (execution control); • a dedicated process through which all communication between the user and the applications is directed (screenoriented); • multi-tasking facilities; • a package o f input/output (I/O ) routines fo r data communication w ith the user.

(

i

t

)

DESIGNER

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3.2 A n Expansion C a p a b ility • The capability to add new application programs to the HOSDES system is fundamental to the design philosophy. • The ’expansion’ capability to add new users to the system, employing an in tri­ cate system o f user-identification, project-identification and passwords. This w ill prevent unauthorized use o f the system o r system data. 249

3.3 Assistance to th e D esigner This capability consists o f a look-alike knowledge-based system. In HOSDES the relationships between the design para­ meters are described by so-called relation­ ship procedures, by which: • the designer can use routines which can find o ut by which parameters a specific parameter value w ill be influenced; • an indication is given by which processes a parameter value may be determined; • a netw ork construction can be ge­ nerated that shows the consecutive processes required to calculate a pa­ rameter, together w ith the other parameters needed to calculate this parameter. D ifferent paths to gain a parameter value are identified. 3.4 U n ifo rm D a ta M aintenance • The HOSDES capabilities are sup­ ported by a rigorous organization of

data structures that are accessible only by HOSDES software tools and not by normal FORTRAN I/O calls. • Many programs are available to the in­ teractive users to manipulate and view (graphically) th e ir data in the database. • A large set o f subroutines is available to the program m er fo r accessing data w ithin the HOSDES environment. These subroutines hide the detailed data structures from the programmer. 3.5 S tand ard A pplicatio n P rog ram s The HOSDES system contains a set o f basic design calculation programs fo r ship de­ sign. These calculation programs are di­ vided into level dependent groups, as follows: • Level 'zero' programs aim at the generation o f a large set o f ship designs using a concept-exploration approach. • Level ’one’ programs are used to check

promising ships found in level 'zero' by othe r more specific methods. Both level ’ze ro ’ and ’one’ do not make use of the 3-D geom etry o f the ship. O nly a set o f up to 60 parameters specify the main ship characteristics. • In level ’tw o ’ the detailled geom etry of the ship is designed o r introduced, together w ith the compartmentation o f the ship. In this level specific pro­ grams are used to obtain more precise and more detailed results fo r the char­ acteristics o f the ships, based on the geom etry thereof. • Finally, in level ’th re e ’ the geom etry of the appendages can be introduced and still more exact calculations may be done to determ ine final ship char­ acteristics. The resulting HOSDES software system can be divided in tw o main parts. First, there is the SUPPORT SYSTEM (see Fig­ ure 4) which contains the software en­ vironm ent fo r the maintenance o f the sys­ tem itself and the software environment fo r the second part o f HOSDES, the APPLIC ATIO N SYSTEM (see Figure 5) which contains the ship design calculation programs. 4. S U P P O R T S Y S T E M S O F T W A R E The support system software is a collec­ tion o f programs, routines and o th e r tools developed to create a software environ­ ment fo r the programs o f the APPLICA­ T IO N SYSTEM. T o achieve the goals men­ tioned above the follow ing subsystems w ere implemented:

Fig. 4. Schematic Representation o f the SUPPORT SYSTEM in HOSDES Fig. 5. Schematic Representation o f the A P P LIC A T IO N SYSTEM in HOSDES

250

4.1 U IM S , U s e r-ln te rfa c e M anage­ m e n t Subsystem This is a program and a set o f routines which handle all interaction between the user and the application programs. High­ lights o f this software subsystem are as follows. • Interactive activation o f application programs through menus. By making a selection on such a menu, an application program can be started. The novice user may go by the menu-tree to the desired program, while the m ore experienced user may enter directly the program name o r type in the menu-tree items. Since menu information is stored in the database, menus can be called-up during runtime. Examples o f tw o existing menus are shown in Figure 6 and 7. • More than one application program can be executed at the same time. This feature is useful fo r calculation programs which, after receiving the co rrect input, w ill have to perform long calculation runs. In that case the user does not have to w ait fo r the completion o f this program. In the mean­ tim e he can execute o th e r programs. HOSDES is true multi-tasking. • A ll user input and output is handled in a uniform manner through forms. Forms are SenW 55STE IA A R G A N G NR (

HOSDES - Level 0 User Interface Management System Menu

1987-03-31 UIMSMEFI

12:12:12 (1 o f 1)

Data Management System Exit to main menu Add ship(s) and/or parameter(s) Compare numerical parameters o f ship options Copy ship(s) and/or parameter(s) Delete (numerical) ship description(s) HISTory list o f ship parameter values List ship(s) and/or parameter(s) Modify ship(s) and/or parameters Restore num. ship description from global View parameters values from categorie(s) Maintain w eight group data Engine Database maintenance

0 1 2 3 4 5 6 7 8 9 10 II SelectFI = A b o rt

Password:

PF2 = Help

PF3 = Exit

▲ Figure 6 - A HOSDES Menu in the USER­ INTERFACE M A N A G E M E N T SUBSYS­ TEM fo r Data Management

HOSDES - Level I Menu

Figure 7 - A HOSDES Menu in the USER­ INTERFACE M A N A G E M E N T SUBSYS­ TEM fo r Selecting Application Programs

User Interface Management System

Design Calculation Programs 0 1

2 3 4 5 6 7 8 Select: FI = A b o rt

Exit to main menu Powering Engine selection Mass Hydrostatics Seakeeping and manoeuvrability Strength Vibrations Performance ---------------Password:

PF2 = Help

PF3 = Exit

1987-03-31 UIMSMEFI

12: 12:12 (I o f I)

keyword. These keywords are unique throughout the system. Routines are available fo r application prog­ rams to w rite , read and cancel keywords. Through this keyword base it is possible fo r application programs to pass non-database parameters to each other. Since each screen field is also associated w ith a keyword, the keyword base is also used to fill the screen w ith (default) input values. The association between progam para­ meters, keywords and screen fields is done w ithin the connection file. This file is filled by the application program m er and is used by the UIMS to obtain specific program information such as which screen to display in o rd er to display the program para­ meters. • The UIMS secures project/user data form unauthorized access through the use of project and user passwords. The data­ base is divided into a global database, which is accessible to everyone (through use o f a ship password), and a local database. The local database is logically divided into a number o f local databases. Each local data­ base has one ’o w n e r’, which is a user w o rk ­ ing fo r a particular project. More than one user can w o rk on the same project, and a user can w o rk on more than one project. AN information in the local database can only be retrieved on a project-user basis. Figure 8 gives a schematic representation o f the User-lnterface Management Sub­ system. 4.2 D M S , D a ta M a n a g e m e n t Subsystem HOSDES uses an integrated relational database system to store all ship informa­ tion. DMS is a set o f programs and routines to manipulate information in this database. Examples are the addition, modification, deletion and listing o f ship and/or ship parameter information, copy ship informaFigure 8 - Schematic Representation o f the USER-INTERFACE M ANAGEMENT SUBSYSTEM in HOSDES

created and maintained through a screen handler. Modification o f screens can be done independently from w ithin the application programs. • An on-line help facility is available through the use o f function keys. In this way the user can obtain comprehensive help information about each application prog­ ram, the input and output parameters, e rro r messages, etc. In fact, a complete user manual is available on-line on the machine and reachable every tim e that input is asked for. More experienced o r expert users w ill receive more concise help information than 'novice' users. • The UIMS enables communication be­ tween applications through the use o f a socalled keyword base. Each program para­ meter w ithin HOSDES is associated w ith a SenW 55STE IA AR G AN G NR I?

251

tion, etc. Special routines are also available fo r comparing ship information, selection of ships fo r fu rthe r investigation, etc. The data structures describing a ship are distinguished by a numerical and a geom et­ ric ship description: • The numerical ship description consists, among o the r things, of: - a ship record w ith ship name identifica­ tion; - design parameter data; - characteristic values o f ship parameters w ith the origin o f the value, the con­ sistency of the parameter and the confi­ dence level; - historic parameter data, w ith char­ acteristic values replaced by new values, created by o the r methods; - parameters whose value depend on the value o f other parameters, fo r instance a resistance curve depending on a velocity range. • The geom etric ship description again is divided into three classes: - the physical ship-description: a data structure representing the physical des­ cription o f contours in term s o f splines; - the logical data structure fo r the con­ tours, describing a ship built up from modules (hull, deckhouse); bounded by components (hull, upperdeck); de­ scribed by contours (frame, w aterline) in terms o f splines, consisting o f a set o f spline segments. - the topological ship description: a data structure representing the topology o f a ship in term s o f modules internally di­ vided into mutually exclusive spaces en­ closed by th e ir bounding planes. Besides these ship data additional informa­ tion about ship appendages may also be stored in the database. This may be com ­ pressed to a few main characteristics o f the appendage or, alternatively, the exact geom etry o f the appendage may be stored as a separate module o r component. 4.3 SM S, System M a n a g e m e n t Sub­ system This is a set o f programs fo r the Application and/or System Manager to maintain the HOSDES environment. It consists o f pro­ grams to: - maintain project information; - maintain user information; - maintain menu information; - maintain all application program in­ formation. Very im portant is the addition and deletion o f application programs to and from HOSDES. This also includes the help-text fo r the programs, the program-related screens, the connection file w ith the rela­ tion between program parameters, screen fields and keywords in the keyword base. Besides this, the validation bounds fo r ap­ plicability o f the m ethod is also stored in the database to prevent use o f a method where this is not allowed, o r to draw the 252

S h ip s p e e d m / s Figure 9 - Example o f Screen Display Provided by te GRAPHICS SUPPORT SUBSYS­ TEM, Showing Calculated Resistance Components fo r ship 'Demo ’ attention o f the user to the fact that the method is not intended fo r the range he is w orking in. A ll this is neccessary to allow HOSDES to be an open-ended system. 4.4 GSS, G raphics S u p p o rt Sub­ system This subsystem consists o f a set o f p ro ­ grams and routines to provide the user means to display graphic information on the screen. This information can either be tables w ith parameter information (for instance speed versus resistance) or geometrical ship information (see Figure 9). This facility also includes the interactive manipulation o f ship compartmentation. Another u tility program offers the possibility to graphically compare several ships and shipoptions on a specific aspect, fo r instance building cost. Comparison on a basis o f more combined aspects may be done by the calculation o f a specific score o f a ship, based on one o r more characteris­ tics, w ith a DMS program. 4.5 D G S , D esigner G uidance Sub­ system This subsystem consists o f a number o f programs to guide the designer in the design process. This includes among o the r things: - consistency checks on all ship para­ meters; - utilities to assist the designer in defining the way to obtain a certain parameter w ith the available calculation programs. 4.6 P IL , P ro g ra m m e r In terfa ce Lib rary This is a set o f routines fo r use by the

applications programmer. W ith in HOS­ DES, (user) input and output functions are separated from computational functions. Besides that, also all database input and output (store and retrieve) functions are separated from computational functions. To be hardware independent as much as possible, all hardware dependent functions are enclosed in separate routines. From these properties it follows that HOSDES application routines have a mo­ dular structure, separating input and out­ put and ship data access from the actual algorithm. The Programmer Interface Library sup­ plies the applications program m er w ith a set o f subroutines which handle all interac­ tio n w ith the outside w orld. In incorpora­ ting existing application programs within HOSDES, the computational functions have to be extracted from the existing program and the co rrect routines from the programmer interface have to be added. Therefore, since the computational func­ tions themselves do not contain any calls to the outside w orld, the function is com­ pletely transportable. 4.7 D C S , D a ta C o m m u n ica tio n Sub­ system This is a program which enables HOSDES to communicate w ith programs on other machines. These can e ither be small perso­ nal computers o r large mainframes. Through this subsystem it is possible to activate programs not included in the HOSDES system. It w ill be possible to up­ load and down-load ship data and to ex­ ecute programs. In the M ARIN situation this subsystem is used to interface HOSDES w ith MARIN programs running on a C D C mainframe. For interactive comSenW 55STE jA A R G A N G NR jj

partmentation, e.g., exchange w ith a personal com puter may be advantageous. 5. A P P L IC A T IO N s y s t e m S O FT W A R E Important tools in computer-aided design are the programs fo r the analysis o f the various design aspects. A survey o f these aspects, implemented in HOSDES, is given in Table I. The HOSDES application software system has been divided into various levels, analo­ gous to sequential trips around the design spiral as portrayed in Figure I . 5.1 T h e ’z e ro ’ level When designing a ship, the starting point will generally be a number o f o w n e r’s requirements concerning ship type, speed, payload, range and operating conditions. These data form the prim ary input fo r the system. The 'zero’ level is intended to define a starting set o f input parameters, w ith which the designer can initiate the actual design process.

designer wants to perform a calculation w ith just one o r tw o application programs, e.g. fo r an existing ship. In that case, the input set w ill often n ot have to be com­ plete. If no satisfactory basis ship is available use can then be made o f a 'm a trix' o f ships defined previously from available data sources, from which can be chosen the most suitable ship, using a special selection procedure based on comparative calcula­ tions w ith respect to required power, seakeeping behaviour, cost, etc. The third, and most fundamental, approach at 'zero' level is the application o f a Con­ cept Exploration Model (CEM) as des­ cribed by Eames and Drummond ( 1976). For this a CEM fo r the ship type under consideration has to be available. A Con­

cept Exploration Model is an integrated design program that can w o rk w ith a re­ stricted number o f design requirements and input data by means o f generating many approximate 'designs’ which can then be compared w ith respect to various prop­ erties to determine the best subset o f designs fo r fu rthe r analysis. This technique enables the designer to obtain an impres­ sion o f the influence o f varying the most im portant design parameters fo r the de­ sign under consideration. Characteristic for such a 'closed' program is the relatively short computing tim e per 'design' because o f the nature of the simple algorithms used fo r the many aspects o f the design consi­ dered, such as the calculations of speedpower, range, fuel consumption, car­ go capacity/payload, seakeeping, cost, etc.

Figure 10 - Diagram Indicating Possible Design Routes on Level 'Z e ro '

If one has available the data o f a good basis ship, the requirements fo r which do not deviate much from those fo r the ship to be designed, then the user does not have to enter the ’zero' level but can proceed directly to 'level one’ w ith parameter values pertaining to that basis ship. These values can be adapted if necessary. A similar approach can be adopted when a Table I - Types o f Application Programs Implemented in HOSDES SUBSYSTEM: CEM Concept ExplorationModel Geometry

geometry o f underwater hull, freeboard and sheer, geom etry o f hull above waterline, subdivision, compartments, appendages

Power

resistance, propeller, p ro ­ pulsion

Mass

payload, light ship, stores and fuel

Hydrostatics hydrostatics, stability, load­ ing conditions, damaged conditions Motions

motions in a seaway, man­ oeuvrability

Strength

bending moments and shear forces

Dynamics

propeller-excited hull pressures and noise

Performance endurance Engine

selection o f engine con­ figuration

SenW 55STE IA AR G AN G NR 12

253

From the designs thus obtained, or obtained from another database, a further selection can be made (using weighting factors, fo r instance) to form a subset fo r further analysis. This is necessary to reduce the m atrix o f possible designs to be persued further. Designs derived by o the r means, not considered above, can be added at will. The approach discussed above is presented diagramatically in the ’outline scheme’ in Figure 10. 5.2 Level ’O n e ’ A fte r having selected an initial set o f main dimensions and o th e r ship parameters in level ’ze ro ’ fo r up to about ten designs, these designs can be investigated further on level ’one’. The main characteristics of this design level is that the ship is still described by a restricted number o f para­ meters (up to about 60 variables have to be Fixed on leaving level ’one' to go to level ’tw o ’). This restriction in describing a de­ sign is in keeping w ith that on level ’zero’. O n level ’one’, if this has not yet been done one level ’zero', the designer has to make (and verify) a number o f decisions, such as the subdivision o f the hull by bulkheads and decks, and approximately define super­ structures and deckhouses (e.g. three layers, over 20% o f the ship’s length). The application programs to be applied on level 'one' are more often than not approximate in nature as those used by the CEM on level ’ze ro ’, that is to say consisting almost entirely o f empirically-obtained formulae that are often ship-type depen­ dent. However, also m ore complex calculation methods, using main dimensions and hull coefficients, may be used here, be it w ith an extensive use o f ’default’ values. Examples o f this are programs fo r estimating resist-

Table 2

-

Survey o f Types o f Application Programs Presently Installed in HOSDES

Subsystem

Level ’ze ro ’

•

Design exploration and generation

•

3-D Geom etry

SHO P5C1 SELECT2 COM PARE2 -

•

Resistance

-

• •

Propeller Power

-

• Engine selection • Mass • Hydrostatics • Seakeeping

-

• • •

-

Manoeuvring Dynamics Performance

* SAC ** TRALIN * * * TRAPAR

1) 2) 3) 4) 5) 6) 7) 8)

Level ’one’

Level ’tw o ’

SAC D EF IN IT IO N *2 T R A LIN G ** TR APA R *** SUBDIVISION2

—

DRAG 11 D R AG 22 DESP3 B-SERIES4 PROPUL1 DESP3 ENGINE2 MASS2

as level 'one' as level ’one' as level ’one’ as level ’one’ RAMASS2 SIKOB/SEASAFE

-

SEAKEEP. PARAM.' SEAKEEP. IN D E X 5 -

EN D U R A N C E2

PR O M O T IO N 6 M A N V R E -I7 PROVIB8 as level ’one’

= sectional area curve = linear transform ation o f hull form = special hull form from transformation procedure, see Van Oossanen and Pieffers (1985)

Extracted from SHOP5C, see Eames and Drum mond (1976) Specially developed fo r HOSDES See H o ltro p (1984) Based on Oosterveld and Van Oossanen (1975); is part o f DESP See M cCreight (1984) Special strip theory developed by MARIN fo r naval combatants See Lyster and Knight (1979) and subsequent adaptations, such as H o o ft (1987) See Holden (1979) and subsequent adaptations, such as W oortm an (1980)

ance and propulsion, such as those o f H o l­ tro p ( 1984), etc. A fte r each calculation the designer must decide w hether o r not to

Figure 11 - Diagram Indicating Possible Design Routes on Level ’One ’

continue w ith the parameter values chosen, o r not. In principle, the sequence in which the programs can be used is arbit­ rary, although in practice some logical sequence w ill usually be applied. Choosing between the various programs may be done by a ’menu’ fo r example. A survey of the calculation methods that car be used on this level (and also on leve ’tw o ’) is given in Table 2. Possible desigr routes on level ’one’ are diagramaticall) presented in Figure 11. In this figure it is also indicated how a user can choose a nev ’starting ship’, or, if none o f the designs selected on level ’ze ro ’ leads to satisfac to ry results, how a new start can be madi at the beginning o f level ’ze ro ’ w ith : different main and/or secondary input o by means o f a new ’initial collection' o designs. If the results o f fu rth e r design refinemen on level ’one’ are found to be satisfactor) one can proceed to the next level, leve ’tw o ’. 5.3 Level ’T w o ’ O n level ’one’ the hull shape was describe by means o f coefficients and single-value

254

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gure 12 has been drawn up in such a way that all calculations that do not use the subdivision o f the hull and the superstruc­ tures and deckhouses are arranged in the second block. This does not mean that this sequence o f performing che calculations is obligatory. O f course, if the subdivision, superstructures, etc. can already be de­ fined o r are already known, then the se­ quence can be chosen freely. It is evident that the definition o f the hull geometry is an essential part of the w o rk on level ’tw o ’. For this task, various approaches may be used as indicated in Figure I 3. The four possibilities used in HOSDES have been discussed by Koops (1985) and are as follows: 1. Use o f an existing hull form , the data o f which are stored in an available data­ base. 2. Transformation o f an existing hull form , input from a database, usually preceded by the transform ation o r generation of a curve o f cross-sectional areas. 3. D ire ct generation o f a new hull form , preceded by the generation o f an o p ti­ mum curve o f cross-sectional areas. 4. ’O th e r’, fo r instance, interpolation be­ tween hull forms o f a ’familiy’ such as the Series 60. t 5.4 Level ’T h r e e ’ For this level no separate diagrams are presented as the application modules used are essentially those o f level 'tw o ', although lesser o r no default values are now used. ’N e w ’ applications that may be added in ^ Block e]

Figure 13 - Diagram Indicating Design Routes in the Subsystem H ull G eom etry (Block I) o f Level 'T w o P ro g ra m s fo r The D ire ct Generation o f the Sectional Area Curve and the H ull Lines Have Yet To Be Implemented Figure 12 - Diagram Indicating Possible Design Routes on Level ’T w o ’ parameters. On level ’tw o ’ the geom etry is designed in a three-dimensional sense. Once the hull form is known in detail the calculations in the next ’block’ (Block 2) can be performed, as indicated in Figure 12. If these calculations have then led to satisfactory results the detailed division of the hull (Block 3) and o f the superstruc­ tures and deckhouses (Block 4) is d ete r­ mined, these data being needed fo r the calculations in Block 5. Once the calcula­ tions in this latter block have been finished and the results have been approved, the ’verification calculations’ o f Block 6 can be carried out. The programs available on this design level, as well as the input used, are basically o f a higher o rd e r’ o f accuracy and detail than those of the previous level (see Table 2, fourth column). Thus, the diagram o f Fi­ SenW 55STE IA AR G AN G NR 12

255

level ’th re e ’ at a later date are, e.g.: - routines to allow small local changes in the hull form ; - programs to allow fo r the detailed de­ sign. o f appendages such as propeller struts, rudders, ducts, bilge keels, etc.; - cavitation calculations fo r propellers and appendages; - lifting line calculations fo r propeller designs; - ultimate stability calculations according to programs presently being developed. These and many more programs can be included in HOSDES because o f the true open-ended nature o f the system. 6. H A R D W A R E C O N F IG U R A ­ T IO N A N D S O F T W A R E S T A N ­ DARDS The current implementation o f HOSDES is on a V A X 8300 com puter from DEC (Digi­ tal Equipment C orporation) running under VMS. The exact configuration needed de­ pends on the amount of use o f the system. For normal use, by less than ten designers, a V A X 11/785 ( 1 1/8100) o r b e tte r is suit­ able. Standard D E C /V T I00 terminals can be used fo r user interaction and a graphics terminal is needed w ith a resolution o f 1024 X 768 o r better. In addition a printer, p lo tte r o r hard-copy unit may be needed. An intelligent graphics terminal to be used fo r local interactive design w o rk (ship compartm entation) is yet to be defined. This w ill probably be a standard personal com puter w ith a high resolution graphics screen. Through the W ork-S tation Manag­ er, software running on o th e r computers may also be connected to the HOSDES system. Use o f a smaller V A X computer, such as a M IC R O VAX , w ill provide the user a lesser performance. One o f the goals o f the HOSDES system was to become hardware independent as much as possible. To achieve this, a lo t o f specific software standards w ere defined in advance. All HOSDES software has been w ritte n in FORTRAN-77 w ith only a few machine-dependent extensions that are collected in a separate library. This is to enable a quick conversion to o th e r compu­ te r systems at a later date, if required. N e x t to its ow n data-management soft­ ware, HOSDES uses the MIMER (version 4.2) database management system. The MIMER system is a relational database package based on a m ulti-user database management system w ith an active data dictionary fo r control o f data storage re­ trieval and security. A part from the data­ base, a screen handler, a re p o rt generator and a query language are also included. W hen no extensions to HOSDES w ill be made by a future user, a run-tim e version o f MIMER is sufficient. For graphical output, a p lo t package de­ veloped at EN R /M AR IN * is used. This package is based on GKS (Graphical Kernel System). Since GKS supports a wide varie­ 256

ty o f graphics devices, by means o f a device­ driver, all graphics input and output be­ come hardware independent. To ex­ change data w ith a graphics w ork-station o r drawing system, the IGES (Initial Graphics Exchange Specification) standard is adopted. This means that the interfacing o f o th e r systems, outside the HOSDES system, w ill also be standard (such as C A T IA and INTERGRAPH). To control the uniform ity o f the system, built from a variety o f existing application programs, the ISO naming convention fo r shipbuilding terms has been adopted w ith ­ in the various application programs. The m ethodology used fo r HOSDES proj­ ect management is based on SDM (System Development M ethodology). The quality o f the results is controlled on the basis o f a ’Quality Assurance Plan’ drawn up accord­ ing to this w o rk method. The resources used fo r reporting during the consecutive phases o f the project are: ’Digital Standard Runoff Commands’ (a DEC te x t processing command language) fo r reporting during the definition study phase and the global design phase, and PDL (’Program Design Language’) is used dur­ ing the detailed design phase. W ith PDL the functions are w ritte n in a program-like manner that is readable and understand­ able fo r both a ship designer and a program­ mer. The te x t part o f this document is included into the program source code, so that the documentation is kept up to date. 7. F IN A L R EM A R K S HOSDES w ill be completed in August 1988 fo r naval combatants. Further de­ velopments w ill then take place to in te r­ face the system w ith advanced threedimensional draughting systems (both C A T IA and INTERGRAPH) and possibly also w ith the structural analysis and design program MAESTRO. Further develop­ ments to make the system applicable fo r othe r ship types w ill then also take place. A study is presently being carried o u t to determine the usefulness o f incorporating special optim ization techniques which would allow the user to optim ize a specific design fo r a specific set o f design require­ ments. The SLIPML procedure described by Mistree and Muster ( 1983) is presently favoured by many in this respect. The development o f HOSDES is moni­ tored by a Steering Group chaired by the Royal Netherlands Navy and composed o f members from De Schelde, Nevesbu and MARIN. Technical advice is provided by a special User’s Group, also composed o f future users o f the system. Dedicated technical and overall project leaders at MARIN supervise the daily w ork, present­ ly involving eight ship designers and soft-

ware specialists. Expertise in software areas not available at MARIN w ere secured under a contract w ith CAP GEMINI o f the Netherlands. The MARIN management has pledged a dedicated e ffo rt in the computer-aided ship design area fo r the coming years. The recent purchase o f a V A X 8300 by MARIN fo r HOSDES was based almost solely on the belief that the ship design expertise of MARIN can yield a very advanced CAD tool in this area, of importance to all con­ cerned in preliminary ship design.

REFERENCES Buxton, I. L. (Aug. 19 7 1): Engineering Economics and Ship Design. British Ship Research Association (BSRA) Report. Eames, M. C. and Drummond, T. G. (1976): Concept Exploration and Approach to Small Warship Design. Transactions RINA. Holden, K. O. (1979): Excitation Forces and After­ body Vibrations Induced by Marine Propeller Blade Cavitation. Norwegian Maritime Research, No. I. Holtrop. J. (1984): A Statistical Re-Analysis o f Resis­ tance and Propulsion Data. International Shipbuilding Progress, Vol. 31, No. 363. Hooft, j. P. ( 1987): Mathematical Description of the Manoeuvrability of High-Speed Surface Ships. MARIN Report No. 47583-l-MO. Koops, A. (Sept. 1985): Hull Form Definition and Computer-Aided Design. IFIP/IFAC Fifth Interna­ tional Conference, Trieste, Italy. Lyster, C. A. and Knight, H. L. (July 1979): Prediction Equations fo r Ships' Turning Circles. Transactions N o rth East Coast Institute o f Engineers and Ship­ builders, Vol. 95, No. 41. McCreight, W . R. (Jan. 1984): Estimating the Seakeeping Qualities o f Destroyer Type Hulls. DTNSRDC Report SP D-I074-0I. Mistree, F. and Muster. D. (Oct, 1983): Design Har­ monization: A Computer-Based Approach fo r Design in the System Age. IFIP WG.5, W orking Conference, Lyon, France. Oosterveld, M. W . C. and Van Oossanen, P. (July 1975): Further Computer-Analyzed Data o f the Wageningen B-Screw Series. International Shipbuild­ ing Progress, Vol. 22, No. 2 5 1. Van Oossanen, P. and Pieffers, j. B. M. (O ct. 1985): NSMB-Systematic Series o f High-Speed Displace­ ment Ship Hull Forms. MARIN Workshop on Hull Form Design, Wageningen. Schip en W erf, Vol. 55, no. 9/10.

* MARIN, together w ith tw o other scientific institutions in the Netherlands, operates a large computing facility called ENR.

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NIEUWSBERICHTEN

Technische informatie W artsila’s N e w Assem bly and T es t Facilities Wartsila Diesel’s latest investment, the new 12,000 square m eter assembly and test facilities in Turku, Finland, have now been completed. The inauguration to ok place in January. The new facilities represent the latest technology available and allow maximum quality control and flexible w orking methods throughout the entire produc­ tion process. The engine types that w ill be assembled and tested in these facilities are the Sulzer, Pielstick and M A N B&W en­ gines produced on licence by W artsila Diesel in Turku and the company's pow er­ ful new medium-speed engine, the Vasa 46. The first Vasa 46 w ill be delivered to the customer in June this year and several additional deliveries are scheduled fo r 1988 and 1989. The free height o f the new hall is 22 meters and the crane capacity 2 x 1 1 0 ton. The testing facilities consist o f tw o separate sound-isolated compartments which makes it possible to test run tw o engines at the same time. These compartments are virtually identical w ith a vessel’s engine room. This makes it possible to obtain results which correspond to a maximum extent w ith those obtained during normal running conditions. During the test the engines and auxiliaries are controlled through a computerized system that in­ cludes 200 different measured parameters. This system is the first o f its kind used by any diesel engine manufacturer. A ll engines can be tested on heavy fuel. R TD Cursussen Bij Röntgen Technische Dienst bv (RTD) te Rotterdam is het nieuwe cursusover­ zicht voor het opleidingsseizoen 88/89 verschenen. De Dienst organiseert thans: • 12 cursussen Ioniserende Straling ni­ veau 5A (IVBS) • 5 cursussen Filmlezen niveau 2 (SKNDO) • 2 cursussen Beknopt NDO/lnspecties. De cursussen worden verzorgd in de pe­ riode van september 1988 t/m april 1989. Het volledige programma is verkrijgbaar bij: SenW 55STE IA AR G AN G NR 12

Röntgen Technische Dienst bv, Afd. O p lei­ dingen, Postbus 10065, 3004 AB R O T­ TERDAM, Tel.: 010-4150200. ’M o n tag e ’ system atisch aangepakt 'Montagegericht' ontw erpen, het meer op 'montage' toespitsen van de organisatie, en het systematiseren van kennis over montagemethoden en -middelen, kunnen to t aanzienlijke besparingen leiden. D it vooral omdat deze maatregelen eenvoud en stan­ daardisatie in het produktieproces bevor­ deren. Mede onder invloed van automatiseringsaspecten is daardoor momenteel sprake van een toenemende belangstelling vo or de montage. De sectie Montage van het Metaalinstituut T N O w il samen m et bedrijven in de metaalelektro-industrie to t enkele gezamen­ lijke projecten op het gebied van de monta­ ge komen en denkt daarbij o.a. aan de volgende onderwerpen: - knelpunten in de montage en mogelijke verbeteringen, - het bevorderen van montagegericht ontwerpen, - mogelijkheden to t standaardiseren in de montage, - criteria vo or het automatiseren van de montage, - mogelijkheden en consequenties van nieuwe verbindings- en montagetech­ nieken. Het is de bedoeling de projectvoorstellen nader u it te werken op basis van specifieke belangstelling u it de industrie. D it zou kun­ nen gebeuren in werkgroepen, samen te stellen uit afgevaardigden van deelnemen­ de bedrijven. De financiering kan worden gerealiseerd door 50% bijdrage van sponsorbedrijven en via T N O 50% stimuleringssubsidie van de overheid. De resultaten van de uit te voeren projecten zijn in eerste instantie exclusief beschikbaar vo or de sponsorbe­ drijven. Geïnteresseerden kunnen informatie over projectvoorstellen, voorwaarden en p ro ­ cedure aanvragen bij de sectie Montage van het Metaalinstituut T N O , postbus 541, 7300 AM Apeldoorn. Telefoon: (055) 773344, toestel 2023.

firm the introduction o f a new manage­ ment quality assurance system fo r the p ro ­ duction plants in Cologne and Mannheim. Up to now, the manufacture and test of marine diesel engines w ere subject to batch-and-line approvals issued fo r specific engine series. Following a detailed pre­ sentation o f the quality assurance systems practiced fo r the D EU TZ M W M engine series and after quality system audits had been carried out in Cologne and Mann­ heim, the company was recently granted the quality assurance approval certificate. The above approval includes all D EU TZ M W M engine series w ithin the pow er range from 20 to 7250 kW . C hem ical-resisting ta n k coating A tank-lining system which is claimed to offer major benefits to ship operators and builders has been developed in Britain. 'Camkote M X ’, from Camrex, is a 3-coat high-performance modified-epoxy tanklining system which provides outstanding resistance to a wide range o f chemicals, solvents and oils. Designed fo r use on the entire range o f cargoes, including land storage tanks and ship cargo tanks and pipelines, the coating system has been specially form ulated to carry such chemicals as methanol, ethanol, vinyl-acetate monomer and acrylonitrile even at high temperatures. The need fo r expensive heat curing has been eliminated, as 7 days’ curing at 20°C is normal. The coating can be applied at temperatures ranging from 0°C to 40°C, making it suitable fo r application w orldw ide. A long pot-life (8 hours at 20°C) and a shelf life o f one year, also ensure benefits to users in warm climates. Because it is highly resistant to chemical absorption, cargo wastage is less likely to occur, and the risks o f contamination be­ tween cargoes and o f coating failure due to cargo interreaction are reduced. Resist­ ance to high-temperature tank cleaning also ensures a fast turnaround between voyages. The coating dries to a smooth m att finish, is nonclogging and offers good sag resistance. More information from : Camrex Coating BV, Postbus 73, Sluisweg 12, Fijnaart. (IPS)

Q u a lity Assurance A p p ro v a l fo r D e u tz -M W M M otoren-W erke Mannheim A G have been the first German engine manufacturers to be handed over quality assurance approval certificates by Lloyd’s Register which con257

VERENIGINGSNIEUWS

w

3= In Memoriam

Agenda

W . M . van Y zen d oo rn O p 2 1 mei j.l. overleed te Rotterdam op 66-jarige leeftijd de heer W . M. van Yzen­ doorn, oud-directeur van de Technische Handelsonderneming Thofex B.V. te R ot­ terdam. De heer Van Yzerdoorn was ruim 31 jaar lid van onze Vereniging.

H olland O ffsh o re 88 Congress The Holland Offshore 88 Congress w ill be held on 15 and 16 N ovem ber 1988 in the RAI Congress C enter in Amsterdam. The Congress C om m ittee fo r Holland Offshore 88, chaired byj. P. H. Huijskens, has succeeded in compiling a very interes­ ting programme o f lectures fo r all involved in the offshore industries. The theme o f the first congress day w ill be Production and the second day w ill be devoted to N ew Technologies. Speakers at this congress w ill give their

Personalia Ing. E. van D ijk T er gelegenheid van zijn 40-jarig jubileum bij de Van Voorden Groep in Zaltbommel werd de heer Ing. E. van D ijk, hoofd van de afdeling O n tw e rp scheepsschroeven en straalbuizen onderscheiden m et de Ere­ medaille in Goud van de O rde van Oranje Nassau. D it w erd gevierd op de op 7 mei j.l. gehouden open dag bij het bedrijf in Z alt­ bommel. N ie u w e V o o rz itte r V N R K Op de 5e Algemene Ledenvergadering van de Vereniging van Nederlandse Reders in de Kleine Handelsvaart gehouden op 'i'V mei j.’i. w eid V.. t . t.n., H oofddirecteur van de Anthony Veder Group gekozen to t V o orzitte r. Drs. Straus is de opvolger van Drs. J. J. Schuld die de voorzittersfunctie vanaf de oprichting der VN R K heeft vervuld. Als plaatsvervangend vo orzitters werden gekozen de heren J. Bouwens, v o o rzitte r van de Raad van Bestuur van Gebr. Broere N.V. en M. J. van O ve rklift, D irecteur Seatrade Groningen B.V.

views on new technologies and future de­ velopments in the offshore industry. Participating in the Holland Offshore 88 Congress not only offers you to learn the views o f leading executives in the offshore industry, but also to see w hat’s new in products and services at the exhibition. The Holland Offshore 88 Congress w ill be held during the Holland Offshore 88 Ex­ hibition. This exhibition w ill be held in the RAI Exhibition C entre, which is adjacent to the RAI Congress Centre, on 15, 16 and 17 Novem ber 1988. Participants in the Holland Offshore 88 Congress w ill have free admittance to the Exhibition. They w ill also receive a cata­ logue o f the Holland Offshore 88 Exhibi­ tion. More information from : Holland Offshore 88, RAI Gebouw B.V., Europaplein, 1078 GZ Amsterdam

N E D E R L A N D S E V E R E N IG IN G V A N T E C H N IC I O P S C H E E P V A A R T G E B IE D VACATURE Binnenkort ontstaat op het Algemeen Secretariaat van de Vereniging te R otter­ dam een vacature vo or de functie van Secretaresse (v /m ). Gezocht w o rd t naar een kandidaat m et ruime ervaring, bij voorkeur opgedaan in de maritieme sector. De functie kan w orden uitgevoerd in een 30-urige w erkw eek en omvat onder meer: - het bijhouden van het ledenbestand dat binnenkort zal worden geautoma­ tiseerd. -

‘rrtA . 't 'w r i t J r f L v r i 'r u t , X

«uH b.'i . 'L 'z s:*r

f J n .
- het bijhouden van het archief. - het corrigeren van drukproeven in de Nederlandse en Engelse taal vo o r het Tijdschrift vo or M aritiem e- en Offshore Techniek. - het verzorgen van een eenvoudige boekhouding. Naast een ruime ervaring als secretaresse w o rd t een grondige kennis van de Engelse taal gewenst. Salaris nader overeentekomen. Sollicitaties te richten aan: De Algemeen Secretaris van de N.V.T.S., Heemraadssingel 193, 3023 CB Rotterdam.

DE SCHELDE KOOPT NOORS DOK De Koninklijke Maatschappij de Schelde (KMS) heeft een drijvend dok gekocht met een hefcapaciteit van 33.000 ton. H et dok is bestemd vo or haar scheepsreparatiew e rf ’Scheldepoort’ in Vlissingen-Oost. H et gaat om de overname van een be­ staand dok van Franaes Industriutvikling A/S in Noorwegen. H et dok zal d oo r ’Scheldepoort’ m et der­ tig m eter worden verlengd, w aardoor de lengte van het dok 228 m eter w ordt. Met d it dok kan de w e rf voldoen aan de vraag naar onderhouds- en reparatiefaciliteiten vo or schepen to t ongeveer 90.000 ton d w t draagvermogen. (Foto: Fre d Hofman Vlissingen) 258

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