Anti-fouling paint
Anti-fouling paint is a specialized category of coatings applied as the outer (outboard) layer to the
Anti-fouling paints are often applied as one component of multi-layer coating systems
History
In the
- The maximum speed of a ship decreases as its hull becomes fouled with marine growth, and its displacement increases.
- Fouling hampers a ship's ability to sail upwind.
- Some marine growth, such as shipworms, would bore into the hull causing severe damage over time.
- The ship may transport harmful marine organisms to other areas.[7]
While anti-fouling coatings began to be developed from 1840 onwards, the first practical commercial anti-fouling coatings were established around 1860.
In an official 1900 Letter from the
During World War II, which included a substantial naval component, the U.S. Navy provided significant funding[10] to the Woods Hole Oceanographic Institution to gather information and conduct research on marine biofouling and technologies for its prevention. This work was published as a book in 1952, the contents of which are available online as individual chapters.[11] The third and final part of this book includes a number of chapters that go into the state of the art at that time for the formulation of anti-fouling paints. Lunn (1974) provides further history.[12]
Modern antifouling paints
In modern times, antifouling paints are formulated with
"Soft", or ablative bottom paints slowly slough off in the water, releasing a copper or zinc based biocide into the water column. The movement of water increases the rate of this action. Ablative paints are widely used on the hulls of recreational vessels and typically are reapplied every 1–3 years. "Contact leaching" paints "create a porous film on the surface. Biocides are held in the pores, and released slowly."[14] Another type of hard bottom paint includes Teflon and silicone coatings which are too slippery for growth to stick. SealCoat systems, which must be professionally applied, dry with small fibers sticking out from the coating surface. These small fibers move in the water, preventing bottom growth from adhering.[14]
Environmental concerns
In the 1960s and 1970s, commercial vessels commonly used bottom paints containing tributyltin, which has been banned in the International Convention on the Control of Harmful Anti-fouling Systems on Ships of the International Maritime Organization due to its serious toxic effects on marine life (such as the collapse of a French shellfish fishery).[15] Now that tributyltin has been banned, the most commonly used anti-fouling bottom paints are copper-based. Copper-based antifouling paints can also have adverse effects on marine organisms. Copper occurs naturally in aquatic systems but can build up in ports or marinas where there are lots of boats. Copper can leach out of anti-fouling paint from the hulls of the boats or fall off the hulls in different sized paint particles. This can lead to higher-than-normal concentrations of copper in the ports or bays.
This excess of copper in the marine ecosystem can have adverse effects on the marine environment and its organisms. In marinas, the river nerite, a brackish water snail, was found to have higher mortality, negative growth, and a large decrease in reproduction compared to areas with no boating. The snails in marinas had more tissue (histopathological) issues and alternations in areas like their gills and gonads as well.[16] Increased exposure to copper from antifouling paint has also been found to decrease enzyme activity in brine shrimp.[17]
Antifouling paint particles can be eaten by zooplankton or other marine species and move up the food chain, bioaccumulating in fish. This accumulation of copper through the food web can cause damage to not only the species eating the particle, but those that are accumulating it in their tissues from their diet.[18] Antifouling paint particles can also end up in the sediment of harbors or bays and damage the benthic environment or the organisms that live in them. These are the known effects of copper based antifouling paint; however, it has not been a large focus of study so the extent of the effects is not fully known. More research is needed to fully understand how these paints and the metals in them affect their environments.
The Port of San Diego is investigating how to reduce copper input from copper-based antifouling coatings,[19] and Washington State has passed a law which may phase in a ban on copper antifouling coatings on recreational vessels beginning in January 2018.[20] However, despite the toxic chemistry of bottom paint and its accumulation in water ways across the globe, a similar ban was rescinded in the Netherlands after the European Union's Scientific Committee on Health and Environmental Risks concluded The Hague had insufficiently justified the law. In an expert opinion, the committee concluded the Netherlands government's explanation "does not provide sufficient sound scientific evidence to show that the use of copper-based antifouling paints in leisure boats presents significant environmental risk."[21]
"Sloughing bottom paints", or "ablative" paints, are an older type of paint designed to create a hull coating which ablates (wears off) slowly, exposing a fresh layer of biocides. Scrubbing a hull with sloughing bottom paint while it is in the water releases its biocides into the environment. One way to reduce the environmental impact from hulls with sloughing bottom paint is to have them hauled out and cleaned at boatyards with a "closed loop" system.[14][22]
Some innovative bottom paints that do not rely on copper or tin have been developed in response to the increasing scrutiny that copper-based ablative bottom paints have received as environmental pollutants.[23][24][25]
A possible future replacement for antifouling paint may be slime. A mesh would cover a ship's hull beneath which a series of pores would supply the slime compound. The compound would turn into a viscous slime on contact with water and coat the mesh. The slime would constantly slough off, carrying away micro-organisms and barnacle larvae.[26][27]
See also
- Biofouling
- Biomimetic antifouling coating
- Environmental impact of paint
References
- ^ "Coating Systems For Underwater Hull Surfaces". NSTCenter. Naval Surface Treatment Center. Retrieved 2016-07-03.
- ^ "Marine Corrosion Explained". MarineCoatingPaint.com. June 29, 2015. Archived from the original on January 8, 2016. Retrieved 2015-10-31.
- ^ Are foul-release paints for you? Coating calculator Archived 2011-07-17 at the Wayback Machine, National Fisherman
- S2CID 137437167.
- S2CID 19773748.
- ^ S2CID 253161460.
- PMID 21324495.
- S2CID 221115202.
- ^ "Letter from the Secretary of the Navy, Transmitting the Views of the Members of the Board on Construction Relative to the Question of Sheathing and Coppering the Three Battle Ships and the Three Armored Cruisers Authorized by the Naval Appropriation Act, Approved March 3, 1899 (p.17, S. Doc. No. 165, 56th Congress, 1st Session)". Google. U.S. Government Printing Office. February 10, 1900. Retrieved 2016-07-06.
- ^ Stetson, Judith (Feb 23, 2011). "Woods Hole in World War II" (PDF). Woods Hole Historical Museum. Retrieved 2016-07-06.
- ^ "Marine fouling and its prevention; prepared for Bureau of Ships, Navy Dept". Woods Hole Oceanographic Institution. United States Naval Institute. 1952. Retrieved 2016-07-06.
- ISBN 0950129917.
- ^ Collins, Andrew P (13 August 2019). "Why So Many Ships Are Red On The Bottom". Jalopnik. Gizmodo Media Group. Retrieved 15 August 2019.
- ^ a b c "Eco-Friendly Boating". eartheasy.
- ^ "Focus on IMO - Anti-fouling systems" (PDF). International Maritime Organisation.
- ^ Bighiu, M.A. 2017. Use and Environmental Impact of Antifouling Paints in the Baltic Sea. [Unpublished dissertation]. Stockholm University.
- PMID 14607547.
- ^ "Marine pollution from antifouling paint particles". 13 February 2019. Archived from the original on 2021-10-27.
- ^ "San Diego Region - Shelter Island Yacht Basin Copper TMDL". Regional Water Quality Control Board - San Diego. Retrieved 2015-10-31.
- ^ [1] the same in May, 2011.
- ^ "EU expert committee challenges Dutch copper-paint restrictions". Free Online Library. 2009. Retrieved 2015-10-31.
- ^ Selecting an anti-fouling paint Archived 2011-09-28 at the Wayback Machine, West Marine
- ^ http://goliath.ecnext.com/coms2/gi_0199-5573950/Fouling-out-coppers-glory-fades.html [dead link] Fouling out: coppers glory fades as new bottom-paint research leads to improved antifouling treatments, National Fisherman, June 2006
- ^ "EPA Reports to Congress on Tributyltin Boat-Bottom Paint" (Press release). EPA. June 20, 1997. Retrieved August 26, 2012.
- ^ http://findarticles.com/p/articles/mi_m0BQK/is_6_10/ai_n15858063/ [dead link] Will California terminate copper paint?, BNET, 2005
- ^ Paul Marks (September 2009). "Slimy-skinned ships to slip smoothly through the seas". New Scientist. Retrieved 28 September 2009.
- ^ "Slime-Covered Boats Could Keep Marine Pests at Bay". 28 September 2009. Retrieved 28 September 2009.
External links
- Selecting an anti-fouling paint, West Marine
- Clean Boating Tip Sheet, Selecting a Bottom Paint, .pdf chart, Maryland Dept. of Natural Resources
- Bottom Paint for Racing Boats, Sailing World, 2007
- Are foul-release paints for you? Coating calculator, National Fisherman
- Using Antifouling paint against the Gribble Menace, Teamac Marine Coatings
- "Focus on IMO - Anti-fouling systems" (PDF). International Maritime Organisation.