Closer look
Since the first boat hit the water sailors have been looking for ways to stop hulls fouling up with marine growth. A quick scan around the Internet in the modern era shows that nothing has changed.
Anti-foul
There are all manner of alternative theories to commercial antifouling including lanolin, zinc oxide, Vaseline applied hot, red pepper and baby’s bottom cream. While this does much for the short-term sales of these products, it does very little in the way of helping keep the growth off your hull.
Early sailing ships suffered greatly at the hands of fouling until it was discovered that thin copper sheathing applied to the bottom did a great job of keeping them clean. In the early 1800s a Birmingham metal worker called George Frederick Muntz developed a cheaper version of this sheathing containing about 60 percent copper and 40 percent zinc.
With the development of iron as a ship building material an alternative method of protecting the surface had to be found as the copper sheathing had trouble adhering to the iron. In 1847 the British Admiralty even considered selling its recently-developed iron ships due to problems with fouling until someone had the bright idea of mixing the copper into paint.
COPPER BASED ANTI-FOULING PAINTS
Copper has a long history of being effective as an anti-fouling substance. Its antimicrobial properties are based on the release of toxic copper ions and copper’s ability to produce a separating layer that is corrosive to spores and juveniles or encrusting organisms. Zinc is usually added to the mix and in days gone by the biocide tributyltin ( TBT) was also added before it became illegal.
ABLATIVE ANTI-FOUL
The majority of anti-foul is ablative which means it gradually wears away as the boat moves through the water exposing fresh biocide to keep the anti-fouling surface active.
Perversely it does not wear evenly and seems to wear out on the leading edge of underwater foils, the waterline and around the stern more quickly. The ‘hardness’ of ablative anti-foul varies.
The harder products tend to be for boats that are moving constantly or fast – like racing yachts – and have the advantage that they can be scrubbed down without losing too much paint in the process.
EPOXY-BASED COPPER ANTI-FOUL
When epoxy is used as the matrix for the anti-foul paint, copper is slowly exposed as the outer layer gets oxidized. Because it is a slow process and less copper is released, manufacturers of epoxy-based copper anti-fouling coatings believe these are more environmentally friendly than other copper-based coatings.
The harder products tend to be for boats that are moving constantly or fast...
The major advantage is the long life of the coating, often exceeding 10 years. Preparation must be meticulous, but if done well maintenance is minimal after application.
COPPER FREE ANTI-FOUL
A growing concern over the environmental impacts of copperbased paints on marine water quality means that many new technologies are being pursued. Although copper is a naturally-occurring compound, in high concentrations it is detrimental to marine life.
US company epaints has developed a copper-free anti-foul which uses sunlight to generate low levels of hydrogen peroxide near the surface of the hull and contains the organic booster biocides of Zinc Omadine or Seanine 211.
Other methods have been developed to make the surface of the hull so slippery that fouling does not get a chance to establish. Teflon and silicone have been used for boats with high hull speeds and fast-moving parts of the underwater sections such as propellers.
While technology and chemistry are helpful, keeping the boat moving seems to be the most effective method of making all this technology work. No matter what anti- foul system you use the boat will become a mussel farm if it does not move.
The one advantage of this is that it will give you more time to scour the Internet for specials on Vaseline, red pepper and baby’s bottom cream.