Fouling of yachts


Fouling of yachts – a headache for yacht owners and authorities alike.

The fouling of yachts is problematic for yacht owners, costing them time and money to keep their boats clean. While traditional anti-fouling paints were quite effective, they leached such large amounts of a toxic chemical known as TBT into the water, that they are now banned by an international convention. The problem with this ban is that it has resulted in much more fouling on vessels because there was no effective alternative to TBT. While this is problematic for yacht owners is also problematic from an invasion biology perspective.
What is ‘invasion biology’ I hear you ask? This is the study of how plants and animals are inadvertently moved around by people. In terms of marine species, most are moved on the hulls of ships or in their ballast water (i.e. the water taken up by ships for balance and trim), but fouling on yachts can also be problematic. If a yacht carrying Australian species were to arrive in Durban, the organisms on the boat might dislodge and happily reattach within the marina. Alternatively, these organisms may reproduce and their offspring could settle.
South Africa has been luck so far, we have not had a new species arrive that has had devastating effects (although there are quite a few with bad impacts in the Western Cape). However, elsewhere in the world such alien species have been very problematic. Fouling species in particular, have cost industry and governments millions of dollars as they block pipes that are used to take up and release seawater. In some regions, people have even suffered negative effects to their health as some alien species can cause diseases while others can result difficulty breathing. From a conservation perspective invasions of alien species are very worrisome. Often these species take over large areas of natural habitat and exclude the native species that belong there.
While countries like Australia and New Zealand are very strict about allowing international yachts into their ports, South Africa has been quite lax until now. One of the challenges to strict boarder biosecurity is the cost involved in cleaning yachts before they are allowed to stay in port. As part of a broader project the Marine Lab at Stellenbosch University is looking at developing an in-water method for removing fouling (and associated alien species) form yachts using a floating defouling berth.
This approach could offer authorities and marinas a way of keeping yachts clean without the costs of hauling them out or the environmental issues associated with simply dropping fouling to the sea floor when its scraped off by divers. This project will be rolled out over the next two years as the method is trailed in various marinas around the coast.
For more information contact Dr Tammy Robinson, Department of Botany and Zoology, Stellenbosch University (Email:

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