Special Door Ing. Th. M. Vollaard
Aangroei verleden tijd Rederij Nova Sea Transport en toeleverancier Luykx Ultrasound BV starten met een innovatief project, waarin onderzoek wordt gedaan naar een ultrasoon systeem dat aangroei op zeeschepen voorkomt. Als het onderzoek en de ontwikkeling slaagt, komt er een product op de markt dat de zeevaart duurzamer maakt en de reders in staat stelt op operationeel gebied winst te behalen.
Het vaargebied van het MS Nova Cura is Noordwest-Europa, en met name de Baltic. Bij de bouw van het schip is hiermee uiteraard rekening gehouden: ze is uitgevoerd met de hoogste ijsklasse. Ook voor de coating op het onderwaterschip gelden specifieke eisen. Gekozen is voor een coating die zeer slijtvast is en daardoor extra goed bestand tegen varen door het ijs. Nadeel echter is dat de coating geen bestanddelen bevat die aangroei voorkomen. Nu het schip door de veranderende marktomstandigheden ook in warmere wateren vaart, is het onvermijdelijk dat zich in snel tempo een aangroeilaag ontwikkelt. Dat heeft lagere vaartsnelheden en een hoger brandstofverbruik tot gevolg. De vermindering in vaart blijkt
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uit ervaring 1 à 2 knopen te zijn. Het milieu wordt zwaarder belast en de operationele kosten stijgen. Om dit te ondervangen, is gezocht naar een inventieve oplossing waarbij rekening wordt gehouden met vaargebied, type schip en milieu. Het streven is een systeem dat aangroei voorkomt of minimaliseert en het milieu niet of nauwelijks beschadigt. Het verbod op het gebruik van tributylinhoudende anti-fouling is hierin een stap geweest.
Werking Het voorkomen van aangroei met behulp van ultrasoon geluid is een principe dat al enige tijd op kleine schaal wordt toegepast in onder
SWZ|MARITIME
Theo Vollaard is stafmedewerker innovatie bij de KVNR
meer zwembaden, de pleziervaart en in opslagtanks voor de industrie. De trillingen die de transducer produceert, worden vele malen heen en weer gekaatst in een tank, tussen kademuur en romp, of in de hele jachthaven. Door ������������������������������ de trillingen scheurt de celwand waarin de levensfuncties van de alge zijn ondergebracht. De biofilm die de voedingsbodem voor de aangroei van algen en schelpdieren vormt, wordt dus voorkomen, en de alge sterft. Bij eerdere toepassingen is gebleken dat dit systeem goed werkt en niet schadelijk is voor mens en vis. Het principe wordt in Amerika toegepast in jachthavens, waarvan men zegt dat ze daardoor geheel vrij zijn van algen en dus aangroei.
men rekening te houden met de wereldwijde inzetbaarheid van de Nova Cura en dus mogelijke ijsvaart. De gevoelige apparatuur zou kunnen beschadigen. Dit is te voorkomen door een gestroomlijnde ijsbestendige behuizing te ontwikkelen, zodat de gevoelige apparatuur veilig kan worden geïnstalleerd. Vanzelfsprekend is het doel het systeem onderhoudsvriendelijk te houden en zo min mogelijk units te gebruiken. In de laatste fase van het project worden de units op één zijde van het schip aangebracht om zo na een aantal maanden goed te kunnen bepalen wat de uitwerking is en welk gebied per unit aangroeivrij wordt gehouden. Als alle fasen van het project goed worden doorlopen, volgt de afronding in mei 2010.
Ultrasone units ontwikkelen Bij eerdere toepassingen werkte het systeem met behulp van terugkaatsing, bijvoorbeeld via een tankwand of kademuur. Een fysische eigenschap van ultrasoon geluid is dat het rechtuit gaat. De achilleshiel van dit project ligt hiermee bloot, aangezien het schip over het algemeen varende is of ten anker ligt op zee. Een andere uitdaging is hoe om te gaan met de rondingen in het onderwaterschip. Door de ronde vormen van het onderwaterschip is het lastig om met enkele ultrasone units het hele onderwaterschip te voorzien van bescherming. In dit project probeert men het systeem zodanig verder te ontwikkelen, dat het onderwaterschip permanent wordt behandeld. In de eerste fase hoopt men een antwoord op deze vragen te vinden en met die kennis ultrasone units te ontwikkelen, die in een later stadium in een proefopstelling in het laboratorium kunnen worden getest en zonodig aangepast. Voordat de units op het onderwaterschip kunnen worden geplaatst voor de proeffase, dient
Een ultrasone unit
Jaargang 130 • juni 2009
Voordelen Naast het voordeel dat aangroei wordt voorkomen, ligt de winst voor de scheepvaart vooral op milieugebied en operationeel gebied. Als geen aangroei wordt gevormd, is de vaart beter gewaarborgd en kan een efficiënter vaarschema worden bereikt. Daarnaast wordt voorkomen dat het brandstofverbruik en de uitstoot van uitlaatgassen toenemen. Het ultrasone systeem kan de toepassing van anti-fouling met schadelijke bestanddelen ter voorkoming van aangroei overbodig maken, hetgeen het mariene milieu ten goede komt. Bij ‘droge’ dokbeurten is de verwachting dat de kosten flink gereduceerd kunnen worden, het schoonmaken van het onderwaterschip is immers niet meer nodig.
Ondersteuning In deze periode van recessie is het opvallend, dat de rederij toch investeert in een nieuwe ontwikkeling waarvan van tevoren niet duidelijk is of die wordt terugverdiend. Anderzijds is het wel zo dat, indien het systeem goed blijkt te werken, de operationale kosten zullen dalen, wat zeer prettig is in deze tijd van recessie. Om dit project doorgang te laten vinden, is vanuit de Subsidieregeling Maritieme Innovatie (SMI) van het Ministerie van Verkeer en Waterstaat subsidie verleend. De ondersteuning van deze regeling is ondergebracht bij Stichting Nederland Maritiem Land (NML) en de Koninklijke Vereniging van Nederlandse Reders (KVNR). De KVNR stimuleert de bij haar aangesloten reders tot innovaties, met ondersteuning door de SMI, en probeert meerdere reders bijeen te brengen om samen innovatieprojecten te starten. NML als overkoepelende clusterorganisatie is met haar grote netwerk in het hele maritieme cluster uitermate geschikt om partijen uit de verschillende takken van de sector bijeen te brengen. Beide organisaties vinden kennisdeling van ontwikkelingen onmisbaar. De voortgang van dit project kan worden gevolgd via de nieuwe website van de KVNR, die begin juni live gaat.
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English Translation
© Copyright translation Luykx Ultrasound bv
Final report AA Project Nova Cura Date: May 2010 Company: Nova Sea Transport Senter Novem project number: SMIK09001 Within the framework of Transport and Public Works Subsidy Legislation and the Temporary Maritime Innovations Subsidy Programme, a subsidy, financed by the Ministry of Transport and Public Works, has been granted by the Maritime Innovations Subsidy Programme. Senter Novem is responsible for managing this scheme.
Contents 1. 2. 3. 4. 5. 6. 7.
Brief summary Introduction Situation prior to commencement of project Project setup Project results Future activities Extensive summary and conclusion
page 1 page 2 page 3 page 3 page 5 page 7 page 8
Brief summary
The AA project proved to be quite extraordinary. In close cooperation with the KVNR and Luykx Ultrasound BV, a unique project – aimed at preventing fouling on the hull of the Nova Cura ocean-going vessel – was completed. Much time was spent doing preliminary investigations into the development of an ultrasonic device strong enough to combat fouling. The pods were hung overboard and hauled back on-board by the crew every time the vessel docked or departed. These pods were hung overboard using long lengths of piping and were linked to the vessel’s electricity grid. Over a period of 9 months, we explored various options for the permanent fixture the pods to the vessel’s hull. Two visual inspections were performed by the crew of the Nova Cura by means of ballasting in order to raise the bow and the stern. Both times, the hull was found to be free of fouling. The hull was again raised and specialist snorkelling equipment was used for the final visual inspection in the clear waters of Croatia and, after 9 months at sea in the Mediterranean and northwest Europe, the hull was found to still be completely clean and free of fouling. We’re now able to look back on an extremely successful project that will benefit the environment and reduce operational costs.
Introduction Project definition and reasoning This project was launched 1,5 years after the purchase of the Nova Cura. In May 2008, the Nova Cura took to the water with a clean, touched-up hull. The underwater paint layer was not antifouling, but paint designed especially for icebreaking and thus had no antifouling properties. After sailing for 1,5 years with speed and fuel consumption affected by fouling, the Nova Cura was dry-docked before the special survey. During the last months before the survey, various methods by which to combat the fouling were investigated. Antifouling paint would not be able to withstand icebreaking activities and the icebreaker paint would have to undergo special treatment in order to bond with the antifouling. The antifouling option would also have been extremely expensive and environmentally taxing. We came upon the idea of trying out ultrasound after noting its use in the horticultural industry. Objective of the project The objective of the project was thus to prevent fouling on the vessel’s hull without the use of environmentally taxing substances, thereby reducing operational costs by enabling greater speed, less fuel consumption and reduced maintenance costs. Collaboration with third parties Collaboration took place with Luykx Ultrasound BV, a company that has been applying ultrasound products within the horticultural industry for some time. In addition, experiences were exchanged with Wagenborg, and we came to the decision to initiate this project with the KVNR (Royal Association of Dutch Ship-owners). In conjunction with Luykx, we considered further steps and adaptations of the product for application in the future. As is visible in the photograph below, upon arrival at the shipyard, the entire length of the vessel was fouled by barnacles and other organisms up to a number of metres up the hull. The following voyages were undertaken in the summer of 2009 up to the start of the study:
1. IJmuiden - Porto Nogaro 2. Bourgas - UK 3. Dunkirk - Bordeaux 4. Antwerp - Oulu 5. Kokkola - Fredericia 6. Heroya - Bordeaux 7. La Pallice -Tanger 8. La Coruna - Varna 9. Kherson - Rotterdam 10. Dunkirk - Rouen 11. Dunkirk - Bordeaux 12. Bayonne - Praia da Vitoria 13. Santander - Gdansk 14. Kaliningrad - Ghent 15. Rotterdam - Runskarr 16. Tahkoluoto - Mersin 17. Reni - Bandirma 18. Hereke - Alexandria 19. Damietta-Tarragona 20. Bilbao-Oran
Situation prior to commencement of project In the photograph above, you’ll see the situation after the trips mentioned. Cruising speed and fuel consumption were severely affected. The cruising speed was 11 knots at 90 % pitch power ratio, and fuel consumption was measured at 11 tons per day. The entire hull was fouled with barnacles, seaweed and other organisms. The box coolers were full of barnacles and the cooler ribs were covered in growth. This drastically reduced cooling ability and, as a result, the vessel could not sail at full steam. Even auxiliary motors were affected by the excessive temperatures. The entire hull was high-pressure cleaned metre by metre and was then touched-up using paint without any antifouling properties.
Nova Cura stern prior to the Special Survey 200
Box cooler area prior to the Special Survey 200
Project setup The decision was made to go ahead with the AA project. Special ultrasound pods that emit a specific frequency were supplied by Luykx Ultrasound BV. These pods were hung from simple galvanised tubing on both sides of the Nova Cura, one at the front of the starboard side facing backwards and one at the back of the port side facing forward. Ultrasound pods were also placed inside the box coolers. These pods did not form part of the AA project and were obtained at the expense of Nova Sea Transport. Before these pods were fitted, the box coolers were removed and treated in an ultrasound bath that removed all the fouling, while the cooling tubes were provided with a layer of special paint. The box cooler housings were sprayed clean and painted, and the coolers were refitted.
At the end of the vessel’s stint in the shipyard, the hull was cleaned and touched up with normal paint. You’ll notice that the ultrasound transmitters (USAF) are placed exactly in the centre of the area most affected by fouling.
Box coolers after cleaning
Subsequently, the following voyages were undertaken: 1. Karlsborg/Rauma-Pasages 2. Marin - Stettin 3. Police - Antwerp 4. Ghent - Marin 5. Dunkirk - Bordeaux 6.Tonnay Charente - New Holland 7. Halsvik - Stettin 8. Klaipeda - Barcelona 9. Castellon - Gijön 10. Vlissingen - Rauma 11. Kotka - Antwerp/Rouen 12. Rekefjord - Kotka 13. Kotka - Savona/Napoli 14. Marseille - Dordrecht 15. Moerdijk - Aalborg 16. Varberg - Terneuzen 17. Vlissingen - Montrose 18. Rotterdam - Mantyluoto 19. Kaskinen - Casablanca + Sfax 20. Ploce – Vlissingen
The above photograph was taken during trip 16 in the Terneuzen harbour. Draught: 1 metre The USAF transmitters were only hung overboard when the vessel was not in motion. While underway, they were not in use, although they were activated when the vessel lay at anchor, provided currents were not too strong. Fouling is generally a problem in the northern Spanish harbours, the Mediterranean harbours, as well as in North Sea harbours. Project results At the start of May 2010, a thorough inspection of the current situation was performed in Ploce harbour, Croatia. Due to the particularly clear water, the entire hull was visible. All ballast was pumped out and the bow and stern were raised as high as possible. The areas that weren’t fully visible were inspected using specially obtained snorkelling gear.
On these photographs, you’ll see the hull around where the ultrasound head was placed. The paint is 9 months old and, within that period, the hull was not cleaned or touched up, but still looks new.
This photograph illustrates the entire bow of the vessel up to the ultrasound pod. This area has thus probably been indirectly – and not directly – affected by ultrasonic waves due to reflection off the quayside or mooring posts, and is completely free of fouling.
The stern, raised to a very shallow draught. The clear Croatian seawater ensured that the hull was well-visible, and it is clearly free of fouling. These photographs illustrate the area around the propeller. The ultrasonic pod was also not directly aimed at this area. It’s possible that the ultrasound pods in the box cooler had an effect here due to reflection off the quayside or mooring posts.
Project goals achieved The above results therefore represent an extremely positive result. After 9 months of sailing - from the vessel’s launch on 5 September 2009 to present, including a late summer, a winter and a spring - the entire sub-surface area of the vessel is still free of fouling. The goals have thus been largely achieved. The cruising speed of the vessel was increased and its fuel consumption was decreased, all resulting in more favourable operational costs. These effects were achieved using a system that does not place a burden on the environment. In addition, maintenance costs have been reduce, as have cleaning costs and paint costs. An extremely notable improvement concerned vibration in the vessel. Thanks to its clean hull, vibration was considerably reduced. Economic efficiency Calm water cruising speed is currently 12 knots at an 80 % pitch power ratio. This has greatly reduced fuel consumption to approximately 9,5 to 10 tons per day, as opposed to 11. Due to better consumption and higher speed, it has become much more viable to set sail and operational costs have been reduced. Cost-savings can be subdivided into 3 categories. The first 2 naturally depend on one another. A. Fuel Consumption
B. Speed
C. Maintenance
Fouled hull: 11 tons/day
Fouled hull: 11 knots/90% trottle
Fouled hull: Cleaning costs
Clean hull: 9,5 tons/day
Clean hull: 12,5 knots/90%
Clean hull: Nil
Saving €100 000/annum*
Saving 10 days or €40 000/annum*
Saving: €2000/annum*
*IFO 380 bunker prices May 2010 based on 200 days at sea *based on a charter rate of €4000 per day *combined cleaning/painting price estimate A. Fuel consumption When compared to the situation prior to the special survey, the saving on fuel is significant. With a clean subsurface area, around 10 % less power is necessary, thereby reducing consumption by approximately 1,3 tons per day. With bunker oil prices at € 400 per ton, this is a saving of € 520 per day. Taking 200 days at sea per annum into account, this is a considerable saving. B. Speed The increase in speed with a clean hull compared to a fouled hull at equal power amounted to 1,5 knots. On longer voyages, this will mean that the vessel will definitely be able to load or unload earlier and that, as a result, more voyages will be possible on an annual basis. It is difficult to determine the actual savings possible, though this will clearly make the vessel more operationally efficient. If the vessel can enjoy 10 extra days at sea on an annual basis, this could yield savings of approximately € 40 000 per annum depending on charter rates.
C. Maintenance and the environment Use of this system considerably reduces the need for maintenance. Much more efficient use can be made of costly icebreaker paint because no more fouling takes place on it. The hull does not require a costly environmentally taxing antifouling layer that loses its effectiveness after a few years and must be replaced. Shipyard cleaning activities can be scrapped or postponed. These costs could amount to approximately € 20 000 on an annual basis. We can also consider the prevention of wear to the engines due to high temperatures. This has not been taken into account in making these calculations.
Applicability Given these results, this system is ideal for use on all vessels that may be affected by any form of fouling. The entire maritime industry can use various forms of ultrasound to keep box coolers, drinking water tanks, ballast tanks, fuel tanks, etc. clean. Non-technical points of interest This concerns ergonomic improvements with respect to the placement of the pods. These would have to be built into the hull. In addition, further research would have to be performed into the reactions of fish and other creatures or the effect on swimmers or divers within the ultrasonic area, although a report by the Hoogheemraadschap Rijnland (Water Board) – which can be viewed via the following link - states that fish are not affected by ultrasound: http://www.visadvies.nl/cms/publish/content/downloaddocument.asp?document_id=58. Another issue at hand concerns possible amendments to maritime legislation and regulations with respect to the use of these systems. Vessels with clean hulls should benefit from lower docking fees. Information distribution within the maritime industry These results and information about the product will be made public via maritime magazines, freight offices, websites, the KVNR, shipping digests and word-of-mouth communication. Social interest of project results This positive result is of great social interest. Vessels will be able to sail without the need for toxic antifouling, meaning that less of a burden will placed on the environment. Less consumption at customary cruising speeds will result in less CO2 emission. There are great ecological advantages to be gained by preventing the spread of organisms via shipping. This largely concerns ballast water and the hulls of vessels. Box coolers can also become clogged with seaweed, algae, barnacles and even (live) crustaceans over time. The continued use of ultrasound can prevent the worldwide carriage of foreign organisms. Future activities In the future, the ultrasonic pods could be fitted to various parts of the hull and inside box coolers as part of the shipbuilding process. During this project, the pods were hauled up and down using lengths of piping. It could, therefore, be done much more ergonomically, or the pods could even be built into the hull. Another possible option could be the use of hydraulic arms to lower the pods below the water surface. A vibration-resistant bracket for use in box coolers has already been designed, positioned in such a way that the ultrasound is radiated into the box cooler at an oblique angle and the signals are thus reflected to all sides.
Ultrasound transmitter USAF®
Ultrasonic emitter bracket system for box coolers
Translation drawing: trillingdempers – shock absorbers steunplaat zender beunkoeler – box cooler transmitter support bracket tussenplaat – mounting plate zender – transmitter beugel – clamp
Unfortunately, it is possible that this report is subject to a certain amount of bias. During the initial period before the Special survey, the Nova Cura spent most of her time in the Mediterranean and did not encounter ice at all. In the time during which the ultrasound pods were use, fewer voyages were undertaken in the Mediterranean and the vessel encountered ice a few times. For definite and irrefutable results that prove the effectiveness of the pods, the vessel will have to undertake multiple voyages in the Mediterranean through the course of a summer. If the hull remains clean throughout such a summer, definitive future steps will be taken, including the development of a CUS (Continuous Ultrasound System) that will constantly protect the hull, box coolers and possibly the ballast tanks by means of ultrasound.
Extensive summary After a few weeks in Harlingen, the Nova Cura already had a layer of fouling on her hull. Subsequently, a number of voyages were undertaken, including some within the Mediterranean. Since the hull was covered in icebreaker paint without any antifouling properties, the layer grew even thicker. Fuel consumption and speed were noted to be poor. In conjunction with Luykx Ultrasound, it was considered to test an ultrasound system in order to avoid having to cover the layer of icebreaker paint with antifouling. Along with the KVNR, a subsidy from Senter Novem was requested. This was granted. As part of the summer 2009 special survey, the hull was cleaned and touched up with regular paint. Two ultrasound pods were brought on board and attached to long lengths of piping that were used to hang them overboard. Two ultrasound pods were also fitted to the box coolers after they had been thoroughly cleaned. After 9 months’ worth of voyages, the results were inspected. In the crystal-clear waters of Croatia, all ballast was pumped out, and the bow and stern were raised as far as possible. The entire subsurface area of the vessel proved to still be clean and completely free of fouling. The project has thus proved to be a success. There are major benefits to be gained from this technology. With respect to the environment, it results in less pollution of seawater due to toxic antifouling. Engine emissions are cut and there are economic benefits to be gained thanks to greater speed and better fuel efficiency. Other benefits include less cleaning work necessary, less dry-dock time, lower engine temperatures and a reduction in vibration. Maritime industry application opportunities include use for the protection of ships’ hulls, ballast tanks, bunker tanks, box coolers and drinking water tanks. The most significant conclusion reached is that, after 9 months, there was no fouling of the vessel’s hull. It therefore appears that the system works effectively. We would, however, recommend that a summer is spent at sea in order to obtain an objective view, since a number of voyages into ice were undertaken. Future steps include the permanent fitting of the pods, adjustments to the ergonomics, the placing of advertisements in maritime magazines and presentations at maritime exhibitions with the aim of marketing the product.
© Copyright translation Luykx Ultrasound bv
