Tuesday, 1 November 2011

Antifouling Environmental Advances for Sailboats and Yachts

Antifouling of sailboats and yachts in these southern climes has been, or about to be actioned along with the usual scraping, hosing, sanding down and rolling on the obligatory odorous very expensive and get everywhere antifoul. Most of us still go through this onerous task with gritted teeth, making it as much fun as we can and espousing to the roped in volunteers that the subsequent summer fun on the water will far outweigh the current misery.

Ultrasonic anti fouling system
 Some brave and adventurous owners have escewed tradition and tried out various alternative options that have presented themselves - some working and some not working with many falling in between - it's all a matter of degrees.
However, as in all things, including marine, progress and advances do occur and in the case of antifouling these advances are mainly prompted by environmental concerns.

The following in depth article is from Roger Reeder who has studied this problem, has some good information and I thought worthwhile reproducing for you here:

'Fouling by marine life is a problem for all yacht owners and has been with us for centuries. My yacht currently requires dry-docking every 12 to 15 months to remove the marine growth from the hull, and new coats of antifoul paint applied.

The new copper-based products are not as effective as the previous tributyltin (TBT) based antifouling paint and must be used more often, has anyone considered the increased effect on marine life of the ‘lesser toxic’ copper-based products applied more frequently?

Tributyltin (TBT) and organic biocides:

TBT – the old antifoul paint was effective but its toxity could devastate marine life and accumulated in the top layer of the open sea in far greater concentrations than expected. The pollutants include toxic metals, carcinogenic organic compounds and highly-poisonous tin compounds.

While the performance of copper biocides cannot approach that of TBT, they remain the most effective of the alternatives for the foreseeable future. To achieve as high a performance as possible from current antifouling products, a ‘booster’ biocide is normally used as copper is not fully effective against all fouling species.

There is currently a great deal of research into alternative forms of biocides, particularly those of organic origin.

These, however, tend to be less universally effective than other biocides and, in particular, may deter only specific types of fouling organism. As a result of these ‘species-specific’ characteristics, such biocides will almost always be used with other biocides, including copper.

The organic biocides are also very expensive to develop and register. They are therefore usually developed and registered in other industries first, such as the agrochemicals industry, for use in other applications. Furthermore, although they are from organic sources there is no assumption that they are inherently less environmentally harmful than any other biocides.

Coral Spawning:

Every November/December, corals spawn all over the reefs of Australia, releasing larvae into the water. These swim free for about two weeks before attaching to an existing reef and developing into juvenile coral polyps – a process that is crucial for the renewal of the reef.

While sailing across the Indian Ocean from Fremantle to Christmas Island my wife and I witnessed the evidence of this mass spawning for days as we sailed north-west in December 2009, the ocean was covered in a layer of orange coloured larvae as far as we could see as per above photograph.

Current antifouling paint (AFP) and its impact:

Copper is the new toxin within AFP (usually cuprous oxide or copper thiocyanate).

An unpublished 2003 study showed that even low levels of copper contamination – below that recorded around inshore reefs off Queensland – reduced the number of larvae that survive to the juvenile polyp stage by at least one third.

The study collected samples of two species of hard coral from part of the Great Barrier Reef near Magnetic Island, off Townsville. Coral samples were placed into “clean” seawater containing two to three parts per billion (ppb) of copper, some in seawater containing 5ppb, and others in seawater containing 30 ppb. The coral was noted to spawn within each sample.

The level of copper had no impact on the total number of larvae produced. But at 5ppb, 30 per cent fewer larvae developed into juveniles, compared with larvae in the clean seawater. At 30ppb, the number was reduced by 70 per cent.

Furthermore, larvae that did successfully mature took much longer to do so in the copper-laced waters than in clean water. The study will continue to test coral samples for any long-term effects. Unfortunately I could find no further information on the web and I invite readers to tell me if further studies have been conducted since 2005.

One of the reasons that studies are not available is that copper is a common seawater contaminant. While it is increasingly used in antifouling paints and is often present in urban and industrial run-off, it does occur naturally in our seas.

Copper is a naturally occurring element and is essential as a trace element for metabolic processes in living organisms. However, it can also prove extremely toxic in high concentrations. Therefore if copper accumulates to a significant degree in the aquatic environment it can have a detrimental effect on marine life.

Copper is present in all human and animal wastes, and non-human activity, such as natural weathering, also leads to copper input into the environment.

Traditional pre-season antifoul
 However, the major sources of copper contamination in inland and coastal waters are industrial wastewater discharges and atmospheric deposition, particularly from foundries and metal plating and cleaning operations. Fungicides, wood preservatives and boat antifouling paints can also contribute to high levels of copper in the aquatic ecosystem.

Due to its complex nature and the uncertainty over its level of interaction with other substances, it is difficult to establish the precise effect of elevated levels of copper in the marine environment. Furthermore, although it may be possible to detect the presence of copper concentrations in sediments by sampling, it is rather more difficult to identify the source of such concentrations.

Depending on the location, sediments can be highly mobile and resuspension of copper in the water column can result in the transportation of the metal to areas away from the main sources.

Therefore, before assumptions can be made concerning the impact of copper-based antifoulant on the marine environment, it is vital that further research is carried out. This should be focused on identifying the sources of elevated levels of copper found in the marine environment and establishing the exact nature of any subsequent environmental impact.

Copper sampling surveys on the reefs off Townsville are few and far between. But the most recent in 2000 found levels of 8ppb in open water – note this is before the majority of the recreational boating industry started using copper-based AFP in lieu of TBT-based AFP. Wet season storms can increase this markedly by stirring up copper-laden sediments.

My local marina is located within Port Stephens and antidote evidence indicates the majority of local yacht owners are still using ablative type AFP like Micron Extra. Yes we have all read about the miracle solutions, and after checking them out realise that very little is available to ordinary yacht owners with limited budgets.

Some local research indicates that the copper-based AFPs may not be destroying the marine life immediately adjacent to hardstand areas where boat cleaning takes place – usually via high pressure hose with the waste product being captured in special purpose tanks.

Jump forward to 2011 and the future:

A search of the web for more current evidence or published research on the impact of copper on marine life was very disappointing. I suspect that eventually the current copper-based products will be banned and yacht owners may be left with few options that actually do what AFP is meant to do – that is stop micro organisms from establishing a foothold on the hull as these little marine organisms are soon followed by their bigger cousins – barnacles, oysters etc.

Current research has suggested that slime, electric charges, laminar air flow, ultra-sonics, nanoShell Metal coating, teflon and even seaweed may help control marine growth on our hulls in the future. In the mean time it remains an expensive and frequent exercise to apply multiple coats of copper-based antifouling paint – there has to be a better solution for yacht owners and the marine environment.'

Roger Reeder is an Electronics Engineer in the aviation industry. He has been sailing dinghies, skiffs and yachts for 56 years.

Extract and coral spawning image courtesy Roger Reeder and Afloat Magazine

You can read more about antifouling, especially in the tropics, in my downloadable ebook 'Voyage of the Little Ship Tere Moana' by clicking on my website www.sailboat2adventure.com 

1 comment:

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