Don't let your hull become this bad!
So as we rapidly approach the start of the 2011 boating season it is time to finish off those last few pre-season jobs and one that is often left until late in the day in the dreaded antifouling. Here we will do our best to remove the mystery and answer some of your questions.
Why Use Antifouling?
The seas around many coastlines contain a mass of animal and plant life forms, all competing for somewhere to live and grow. These tiny organisms include the larvae of literally billions of barnacles, mussels and other sea creatures, together with seaweed spores from around the world. Generally these lifeforms isare most concentrated around our coasts and in harbours and estuaries, where a rich source of food on which these organisms can thrive can be found. Indeed, plankton is often dense enough to be visible during the day and can sometimes be seen glowing on really dark nights. Everything in the sea is bathed in this ’soup’ of living matter, and can become badly fouled within just a few weeks unless protected by an effective anti-fouling.Apart from looking unsightly, heavy fouling makes your boat slow, less responsive, less fuel efficient and difficult to manoeuvre in close quarters situations
There are so many types of antifouling, which will be right for my boat?
Most anti-foul coatings are designed to cope with a wide spectrum of fouling and generally speaking there are three main types of antifouling, for a range of hull types and mooring conditions:-
Self Polishing (eroding) – the popular choice As the term suggests, think of a bar of soap and this helps to describe the relative soft nature of these products and how they work. Through the flow of water across the hull a fresh layer of biocide is continually exposed on the outside to repel any fouling. Provided that sufficient coats are applied from the outset, multi-season performance can be expected, saving you time and money. Once applied an annual check and jet-wash on the hull, to revive the coating, is normally all that is needed. Most users find that the overall performance of self polishing antifouling is very hard to beat. Understandably boats with drying moorings are not really suited to these products.
Hard types – These products have a general appeal and will work just as well in a range of conditions including salt and fresh water. Due to the leaching nature of the biocide, these products do not erode as such and can be used for drying moorings. Hard types are resistant to abrasion and often favoured by racers who can burnish the hull with wet & dry prior to launching. Hard types can be effective up to very high boat speeds of up to 70 knots and often favoured by powerful motorboat owners. These products are best re-applied on an annual basis.
Non biocidal – foul release types These work due to the slippery nature of the surface, which fouling finds difficult to adhere to. As a result they are not normally suitable for drying moorings. The other major benefit, is less water resistance on the hull, meaning better fuel economy and more responsive handling through the helm.
There is a vast array of products on the market
– Put on old clothes and if you feel it warrants it a set of overalls on top as further protection, along with rubber gloves and safety glasses or goggles. Apply masking tape around the waterline and mask off anodes, shafts and fittings to protect them from unwanted coating. Put a plastic sheet down to protect the ground and wet the ground with water to prevent dust rising onto your work. If you are working on a cold day, keep your paint in a warm place or stand the tin in a bucket, part filled with warm water. This will make it easier to apply and give a smoother finish. Anti-foul can settle, so vigorous stirring with a flat object is recommended. Don’t use paint directly from the can if you can avoid it, put an appropriate amount in a roller tray and replace the lid. This prevents contamination and premature ageing of the main can contents. Remember to occasionally stir up the tray contents during your work. Anti-foul is best applied with a roller, but keep a brush handy for those awkward to reach areas. When using a roller, apply the coating in a ‘criss-cross’ pattern, as if you were using a brush. This helps spread the coating evenly. Apply an extra coat at the leading edges and waterline area, as this is where the boat faces more water- flow. Finally, as soon as the anti-foul feels ‘tacky’ remove the masking tape before the paint dries hard, to give a smoother edge to the paint and one that does not stand proud of the surface. Stand back and congratulate yourself on a job well done with a well earned hot drink!
Surface preparation – Surfaces to be painted must be clean, dry and free of oil or grease. Bare surfaces must first be primed with a suitable priming scheme, filling any undulations between coats with an epoxy profiling filler . Existing anti-foulings don’t usually need any special preparation, but they can be lightly wet sanded, using fresh water, to remove small lumps and ‘blebs’ in the paintwork. Propellers can be cleaned with an electric drill and wire brush to give a smooth, polished finish.
Priming the underwater hull – On bare and filled areas, you should apply touch-ups of primer to ensure good adhesion of the coats to follow. For hulls where all the existing paint is removed and full coats of the primer system are required, use an epoxy primer. Be sure to observe the over coating intervals between each coat – Seajet put this information on the tin. Use a brush for smaller areas and a roller for larger areas. If you don’t know what anti-fouling was last used on your boat, or the condition of the boat is not ideal, apply a good sealer coat. Applying anti-fouling Generally speaking the performance of anti-foul is directly proportional to the dry film thickness of each coat. Therefore it is important that you apply the recommended quantity as a minimum for a satisfactory result. Where possible apply your anti-fouling during late morning or early afternoon in calm, dry weather. Avoid the risk of dampness or overnight dew, as this will spoil the results and subsequently affect the performance.
Thanks to Seajet for their help in compiling this article
Waterside Boat Sales are delighted to annouce they will be attending the 2011 London Boat Show and will be offering not only unbeatable deals for customers looking to 
