Step into any chandlery, right now, and you will be faced by a mountain of shiny tins of different types of antifoul. Which to choose? There is no simple answer, no “one-size-fits-all” solution - which is one reason why the stuff is so expensive.
In fact it is so expensive that a lot of people are tempted to do without. Unless you take the even more expensive route of dry sailing - having your boat hauled out of the water between outings - that is not really an option.
Any boat left afloat will accumulate a coat of “slime,” actually composed of millions of microscopic marine organisms. If this is not removed, the hull will “grow” barnacles, and then fronds - and ultimately a healthy “beard” of seaweed.
Heavy fouling not only makes the boat slower, it also makes it less responsive to rudder and engine, and therefore harder to handle in any weather, which could have serious safety implications. It can also cause damage to the hull itself: the natural glues the organisms use to attach themselves can degrade both wood and GRP.
Loss of speed caused by the increased drag of fouling means less enjoyment in sailing and also increased fuel costs, so skimping on antifouling is false economy.
If you are concerned about environmental damage from antifouling, remember that there is also an environmental cost to not antifouling: invasive marine species may be transferred from one area to another by untreated boats.
So most of us accept, however reluctantly, that antifouling is an inevitable annual chore. Year after year we buy these expensive tins of paint, face the unpleasant job of putting it on, and are often sadly disappointed by the results. The paint manufacturers would say this is because we have not chosen the right product for our particular circumstances. But with so many to choose from - International alone offers nine different types, and Blakes, SeaJet and others offer comprehensive ranges - where do you start?
Basically, antifouls fall into three categories: eroding (also described as self polishing), hard, and “slippery.”
Eroding antifouls are the most popular choice for cruising yachts. They are relatively soft, and the outer layer is constantly being (very slowly) dissolved by the flow of water across the hull. This means that a fresh layer of the biocide within the paint is continually being exposed to repel fouling.
Manufacturers claim that providing sufficient coats are applied from the outset, this type of antifoul can last for more than one season, saving time and money. Eroding antifoul is most effective where boats do a high mileage. A long passage, or a lively beat, will often effectively clean light growth from hull. One disadvantage is that wiping off any slime that does grow will also wipe off a considerable amount of antifoul!
Hard antifouls work by gradual leaching of the biocide. Because they don't erode, they are more resistant to abrasion, and therefore more suitable for boats on drying moorings. They are also suitable for high speed motorboats which would wear off the eroding type too quickly. And they are the choice for racing yachts because they can be burnished to a perfectly smooth finish.
They may seem less effective in controlling fouling than the eroding type, but again keeping the boat on the move helps to keep it clean. And boats can be dried and scrubbed during the season without damaging this type of antifoul. Because of its leaching nature, the biocide will be exhausted by the end of a season, and so hard antifoul must be reapplied annually.
Slippery antifouls do not contain a biocide, but work because of the “non-stick” nature of the surface: for example, Teflon, as used in non-stick pans, may be an ingredient. As well as making it difficult for fouling to stick, they are claimed to make the hull less water-resistant, giving more responsive performance and better fuel economy. Relatively expensive, these are generally the preserve of racing boats, and are emphatically not recommended for drying moorings.
It's worth remembering that the type and severity of fouling can vary from place to place and year to year. It is influenced by such factors as salinity, water flow, temperature and sunlight hours, and of course pollution. Agricultural run off and sewage outfalls can provide a rich source of nutrients for the algae and plankton which cause fouling.
So if the antifoul you used last year proved disappointing, it may indeed be because it was not the type best suited to your particular circumstances. It's worth asking marina or moorings neighbours what they're using, to find out what works best - and what doesn't - in your area.
What's most expensive isn't necessarily best, and what's cheapest isn't a good bargain if it doesn't do the job. Different people will have different experience of different products, but the chances are that a strong local preference will emerge.
Whatever antifoul you eventually decide to use, how well it performs will be greatly influenced by how well it is put on. Do read the manufacturers' specification and safety sheets, check for compatibility with coatings already on the hull, remove any old antifoul in poor condition before you start, and check advice on application temperature and humidity.
All the major paint manufacturers offer advice about choosing the right antifoul and the best methods of preparation and application on their websites. For more information visit www.yachtpaint.com, www.blakespaints.com, www.seajetpaint.com, www.xm-yachting.co.uk, www.eu45antifoul.com
What antifoul did you use in 2006? How well did it work? Please write a user review
to help other MainSail members decide which antifoul to buy this year.
