The performance of thebiocide-free anti-foulingcoatings suggest thatsome of these providepromising alternatives toorganotins for coastalvessels. However, resultsvary depending on theships’ operatingconditions and severalparameters should betaken into account whenconsidering a suitablesystem for a respectiveship. The silicone-basednon-stick coatings andthe self-polishing paintwithout biocides seem towork fairly well undervarious conditions,especially on fast movingvessels. The fibre-flocksystem performed welleven on a slow movingvessel with long harbourperiods. Additionally forbrackish water,hydroviscosic paints andTeflon-based non-stickcoatings combined withcleaning, seem to beviable alternatives. Theuse of anti-corrosive paintonly, on fast-movingvessels, may beappropriate under certainconditions, which makesthe application of anti-fouling systemsunnecessary. However,conditions at the time of application seem to be important for bothalternatives and organotin coatings.

Co-operation betweenstakeholders developedwell, providing a modelfor future acceptance ofalternatives.

General conclusions

As the alternatives workin a different way, somesettling may occur.Shipowners have to beconvinced that nodamage to the ship’s hulloccurs and that foulingcan be removed cost-effectively without actuallyremoving the coatingsusing water currents onfast vessels or bycleaning on slow-movingships. It is of crucialimportance thattechnological solutionsmust be acceptable tothose who are expectedto use them.

MinistriesMinistry of Environment Lower-Saxony, Ministry of EnvironmentHamburg, Ministry of EnvironmentSchleswig-Holstein

Ship ownersAG Ems, AG Norden-Frisia, WykerDampfschiffs- Reederei, Insel undHalligreederei Kurt Paulsen, HADAG,Manfred Friedhoff, Coastal guardLower-Saxony, Coastal Researchstation of Lower-Saxony

Paint manufacturesCHUGOKU Germany, Colloid,Hempel Germany, Akzo Nobel(International Farbenwerke –Akzonobel.), Relius Coatings, SIGMACoatings, SealCoat, Tenax MarinePaints, NorAgent (Lotrec), WilckensFarben/Kansai, CK Witco

Scientific LaboratoriesLaboratory for Freshwater/ MarineResearch and Comparative Pathology(LimnoMar), Coastal Research stationof Lower-Saxony, Ministry ofEnvironment Hamburg, Department ofConservation – Environmental Analysis

German coast

ship trials testing

biocide-freeanti-fouling systems

WWF-UKPanda House, Weyside ParkGodalming, Surrey GU7 1XR

Tel: +44 (0)1483 426444Fax: +44 (0)1483 426409

www.wwf-uk.org

German coast

ship trials testing

biocide-freeanti-fouling systems

trial. The fast-movingpatrol boat operating inbrackish to freshwater,coated with an anti-corrosive paint only, wascovered with a biofilmcomprising minusculeforms of macro- andmicro- algae which wereeasily removed. Thefishing boat coated withsilicones and one self-polishing paint showedonly minor fouling duringthe two-year period.

Control applications(anti-fouling paints with biocides)These investigationsincluded biocide-containing controls.Fouling occurred on thesecontrol paints, on occasionto a higher degree than onthe non-biocide coatings.

Chemical investigationsThe non-stick coatingsand the self-polishingpaints without biocides did not exhibit acuteecotoxicity. Generally,chemical analysis offouling organisms reflected the contamin-ation of the surroundingwater body. However,PolyaromaticHydrocarbons (PAHs) were found at elevatedlevels, and may haveleached from underlyinganti-corrosive paints. This should be taken intoaccount when consideringthe sealing of organotinanti-foulants as an optionfor adhering to the ban onorganotin presence onships hulls in 2008.

WWF GermanyMarine and Coastal DivisionAm Guthpol 11D-28757 Bremen

Tel: +49 421 65846 10Fax: +49 421 65846 12

www.wwf.de

Results(continued)

In total 23 biocide-freeformulations were testedand compared withcontrols based on TBT,copper and organicbiocides.The ships takingpart in the project operatein estuaries in the harbourof Hamburg, the NorthSea, the Wadden Sea and up to 100 nauticalmiles offshore in theGerman Bight. Thesewaters vary betweenmarine, brackish andfreshwater. Test conditions vary andinclude, for example,ships which have contactwith the sea bottom andthose which do not;fouling pressures whichrange from high to low;and a range of speedsfrom slow moving ships tofast coastguard vessels(5, 12 and 19 knots).

Following an initiative byWWF Germany and theMinistries of Environmentof Lower-Saxony,Hamburg and Schleswig-Hostein in 1998 threemulti-stakeholderprojects were initiatedinvolving the testing ofenvironmentally soundbiocide-free alternativesfor vessels in coastal andbrackish waters. Theproject in Hamburg andSchleswig-Holstein wasundertaken for one year,in Lower-Saxony theproject was carried outfor two years in order toassess the durability ofthe coatings during thewinter and to determine whether the durabilityand effectiveness couldbe maintained for severalyears. Chemicalinvestigations of thefouling organisms andeco-toxicity testing of thepaints were performedwithin the Hamburgproject only.

The projects involved awide range of interestgroups, including the threeMinistries, eight shippingcompanies (both federaland private), eleven paintmanufacturers, theGerman PaintManufacture Association,and WWF-Germany. The Laboratory for Fresh-water/Marine Researchand ComparativePathology (LimnoMar),the Coastal ResearchStation of Lower-Saxony,and the Ministry ofEnvironment Hamburg,performed the scientificinvestigations. Ministries,shipping companies, paintmanufacturers and WWFjointly provided funding.The project in Lower

Saxony was also fundedby the NiedersächsischeWattenmeerStiftung(Waddensea Foundationof Lower Saxony) and theEnvironmental LotteryBingo-Lotto.

The aim of the projectwas to test alternativepaints on ship hulls ofover 25m in lengthoperating in coastaland/or brackish waters.Each hull was cleaned inthe spring and analternative paint applied(several stripes of paintper hull or one coat forthe complete hull). Thepaint manufacturersprovided free samples ofthe test-paints, whichwere applied under themanufacturers’ super-vision. The ships thenoperated under normalconditions and scientistsinvestigated the vesselsregularly. The investigationincluded type andcoverage of fouling, thedry weight of the foulingcommunity, adhesionstrength and paintcondition.

A number of existingecological alternativeshave been tested:

• non-toxic, non-stickcoatings to preventsettling (smoothsilicone, teflon or hydroviscosic coatings)

• self-polishing, anti-fouling paintswithout biocides

• fibre-flock coatings

• hard, non-abrasivecoatings in combinationwith special cleaningprocedures (e.g. hydrojetting, rotating bristles)

Results

on sea-going vesselsunder 25 metres inlength. This curtailed itsuse on recreational craft.However, although inputsof organotins have beenreduced in some coastalwaters of countries wherethe ban was imposed, thecontinued use of thesepaints on ocean-goingvessels is still resulting inlarge releases of toxicchemicals into the marineenvironment. In areasclose to ports anddockyards, marine snailsare affected and arefrequently in decline.Effects on marine snailshave also been reportedin busy shipping lanes inthe North Sea. Moreover,TBT is found in seabirds,marine mammals and fishfor human consumptionall over the world.

Fouling organisms growor cling onto the bottomof boats, interfering withthe performance anddurability of the craft.They include both animals(e.g. barnacles, molluscs,polychaete worms,encrusting hydroids,bryozoa and sea squirts)and plants (e.g. green,red and brown algae and diatoms). In order toprevent them from settling,biocide containing anti-fouling paints are used,mainly containing TBT(tributyltin), known for itshighly toxic and endocrinedisrupting properties.Additionally, new researchhighlights the possibilityof TBT exhibiting humanendocrine disruptingproperties.

Many countries haverecognised thedetrimental impacts ofTBT and banned its use

Background

The InternationalMaritime Organisation(IMO) adopted anAssembly Resolution inNovember 1999, whichshould ensure a globalban on the application oforganotins in anti-foulingpaints by 2003. IMOfurther recognised ‘theimportance of protectingthe marine environmentfrom adverse effects ofanti-fouling systemsused on ships’, and ‘the need to continue to develop anti-foulingsystems which are effective andenvironmentally safe’. IMO member states wereasked ‘to encourageindustries to continue todevelop, test, and use,as a high priority, anti-fouling systems whichdo not adversely impactnon-target species andotherwise degrade themarine environment’.

The project

The results suggest thatsome of the biocide-freepaints provide promisingalternatives to organotinpaints. Although foulingstill occurs to somedegree, this can be easilyremedied by sailing theship at high speed or bymechanical cleaning.However, results varydepending on the ships’operating conditions.

Non-stick coatings All tested silicone-basedcoatings were fairlyeffective. Although foulingdoes develop to a certaindegree, most of theorganisms do not adherestrongly. On all silicone-based coatings theadhesion force ofbarnacles wassubstantially reduced incomparison with surfacessuch as epoxy resins.Algae growth was alsoreduced. The siliconecoatings could be cleanedeasily with a waterpressure of 1-10 bars. Onfast moving vessels suchas the coastguard patrolboat, these coatings weremore effective than onslow moving vessels andthose with a high

percentage of days inharbour. All silicon coatingremained intact through-out the trials and evenperfomed well in thesecond year of the trial.Silicon coatings wereremoved from the hullwith high pressure hydro-blasting (1200-1500 bars).This removal did not causeproblems with adhesion ofthe next coating.

The tested hydroviscosicpaint and the Teflon-basedcoatings did not performwell in seawater, but couldbe cleaned efficiently whenthe ship was operating inbrackish water only.However, more power wasrequired to clean thesecoatings compared withthe silicone coatings.

Self-polishing, anti-fouling paintswithout biocidesOne of the two self-polishing coatingsperformed well, especiallyon fast moving vessels.Adhesion of barnacles andtotal length of algae werereduced. Whenever ‘greenfouling’ (algae) occurred, itwas removed easily fromthis coating.

Fibre-flock systemThis technique simulatesseal skin, continual motionof fibres initiates a self-polishing process. Duringthe project this coatingperformed well, withselective effectivenessagainst barnacles evenon slow vessels with long harbour periods. Algae growth was alsonegligible. The systemwas only tested in thesecond year of the trial,but manufacturers claim it is effective forthree to five years.

Hard, non-abrasivecoatingsOne coating of this typewas tested in thisproject, and only in thefirst year. This non-abrasive coating wasinappropriate for use inseawater, so cleaningwas ineffective. Improve-ment is necessary andfurther investigation isneeded.

Brackish watersTest paints on most shipsoperating in brackishwaters, partly brackish orfresh waters performedwell during the two-year

TBT is found in

seabirds, marine

mammals and

fish for human

consumption all

over the world.

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