The right antifouling – what you need to know

Have you ever looked at the bottom of your boat and wondered if you have the correct underwater coating?

A recent poll suggested 72 percent of boat owners do not know the best antifoul or underwater coatings for their boats, and have either purchased the cheapest product from their chandlery or paid over the odds for someone to antifoul their yacht for them.
 
Antifouling is in fact a critical part of your annual yacht maintenance to get right, as the repercussions for the incorrect underwater coatings could have significant long term effects to the bottom of your boat.
 
In order to select which type of underwater coating or antifoul you need for your boat, you first have to look into what sort of activities or voyages you are likely to do throughout the year. You can then decide from the following list what type of underwater coating you you require.
 

Antifoul

· Eroding antifoul

· Long lasting Antifoul with Copper extracts

Epoxy Coatings

· Epoxy primers

· Epoxy top coats

What is self eroding antifouling?

Eroding antifoul, as the name suggests, wear away leaving eventually no antifouling on your hull. In theory, whilst there is antifouling on your hull it will give a degree of protection.
 
The Antifouls are designed specifically to your boats speed. If you are a sailing boat achieving a max of 7 knots, then eroding antifoul will work for your needs. However, if you are a motor yacht with speeds in excess of 25 knots, then you are likely to lose your antifoul well before the desired time line.
 
Eroding antifouls are great for those who prefer a low maintenance option, as generally speaking there is far less accumulation of old paint on the hull after each season. However, a slow build up can still occur if excessive paint is applied at each application. This will eventually need to be removed as it may become unstable and lead to problems when new antifouling is applied.
 

What is Hard Antifouling?

Hard antifouls work by releasing biocide from the surface of the coating to deter fouling organisms. Hard antifouls don’t really wear away, but Biocide leaching rate reduces over the lifetime of the product. After a few seasons, there may be a residual build-up of product that needs to be removed.
 
If you have a fast boat, or a boat that is used very regularly, then hard antifouling is usually the best product to choose. Boats moored in fresh water normally use these types as eroding antifoulings are designed to erode in salt water and may not erode sufficiently in fresh water.
 
For the avid racer, Harder antifouls are an attractive option, as you are able to sand the antifoul smooth for a better flow in the water, and it will still operate as normal. P.S If you are one of these avid racers, please make sure you put more than enough coats of paint on prior to sanding.

Self Polishing Antifouling’s (SPC)

Known variously as self-polishing (SPC), ablative or eroding antifouling paint, this softer, soluble coating is designed to erode fairly quickly to ensure a fresh layer of biocide is always present on the surface.
 
SPCs release biocide at near constant rate throughout their life. The diffusion of the biocide on the hull surface is primarily due to a chemical reaction between the paint and seawater. Not only is the biocide layer cleaned and replenished when the vessel moves through the water, but it also continues to work when the vessel is moored up. In SPCs, however, the active biocides are depleted more quickly than in a hard antifouling, so you need to apply at least two coats for a season’s sailing.

Copper extract antifouling

When your boat hits the water, the sea water attacks the exposed copper extracts, causing the formation of cuprous oxide. This highly effective antifouling agent deters growth until the surface degrades further to become cupric hydrochloride. This final copper form is highly unstable, and is washed away by the movement of the yacht, thereby removing any accumulating silt or slime. This automatically reveals a fresh copper rich surface, whereby the process recommences

Epoxy Primers and Topcoats

For the boat owner that is able to dry sail their yacht, or have access to dry stacking facility, it is prudent that you still put an underwater coating to protect the gel coat below the water line. Often, yachts apply an epoxy coating to the bottoms, which allow you to sand it smooth and polish to get an almost new finish again.
 
The epoxy coating doesn’t protect your bottom from growth if the boat has been in the water for a lengthy period of time, but it does protect the bottom to some degree when short trips or shorter periods of water berthings.
 
Once you have considered all of the above information on what underwater coating you should be using, you then have the decision of brand. Which there are many. The leaders in the industry are undoubtably International, but there are many other brands that have challenged the pedestal such as Hempel, Nautix and SeaJet. All of which generally do a very similar job, but will differ in application.

Applications

The application of the antifoul is probably the most important part of your underwater coating efficiency. All coatings, be it underwater or topcoats, require certain temperatures to cure. If you apply your coating under the desired temperature, it is likely the coating will not last the desired time, and you will be left having to redo the job. So make sure your read the data sheets for the coatings prior to application which will give a step by step guide to preparations, cleaning agents, and curing temperatures

Insurance Connotation

To remain in theme with offering the best insurance options to our clients, we’re going to weigh in on the impact to your insurance of antifouling. There ultimately is no specific requirement from insurers to choose one type or brand over another. The important thing to consider, however, is that you do carry out your annual antifouling. Failing to do this will cause excessive growth on your hull,
 
which could cause wear and tear related damage that can ultimately lead to losses such as sinking. This is almost certainly excluded by every insurer, and needs to be kept on top of by all prudent yacht and boat owners.