Types of AntiFouling Systems

Traditional anti-fouling paints work via the activity of a biocide – a substance intended to render harmless or control any harmful organisms by chemical or biological means. The prevailing biocide used in the majority of antifouling treatments is copper, with around 90% of antifouling jobs using copper as the active element. However modern developments are showing a trend away from biocides, and new treatments are emerging that use differing elements to combat biofouling.

Traditional Anti-Fouling Treatments for underwater hulls.

The mechanism used by biocidal Anti Fouling paints cause biocides to dissolve into the water, with fluctuations depending on the coating finish. Coupling the correct delivery system with the substrate, environment, and usage of the boat is critically important for the accurate operating of the anti-fouling. The two main types of biocide anti-fouling treatments are:

Eroding antifouling

As it’s name indicates, this finish utilizes erosion to deliver biocides. This can be triggered by the movement of the seawater over the boats hull, or by a biochemical response which is created on the surface of the antifouling applied. The biocides are released in a controlled fashion that delivers longer, more consistent biofoul protection. Unlike hard film antifouling, vessels painted with eroding antifoul can be hauled and relaunched without the need to repaint, because the biocides are bound chemically to the paint and only active in water.

Hard film antifouling

The delivery mechanics for this types of anti-fouling paint is known as ‘contact leaching’. The application is filled with biocide, and contact with seawater causes the biocides to leach away. Because of this, the antifouling protection is not constant – it begins high, then declines as the biocides leach away, leaving just the hard paint film. These anti fouling coatings also decline in their anti-fouling ability if not in the water, meaning that they cannot be hauled out of the water and relaunched without repainting.

Innovative AntiFouling Control Coatings

Current developments, including the trend towards sustainability and friendlier “green” coatings is driving the examination of alternative anti-fouling procedures that do not require the use of a biocide. These include new experimental treatments such as teflon or silicone coatings, hydrophobic, and textured hulls which may delay or prevent the biofouling from growing, known as foul release coatings.

Foul release coatings also include silicone elastomers, fluoropolymer-based coatings, ceramic coatings, and wax coatings. These anti-fouling coatings are additionally known as foul release applications because the chemical mechanism does not prevent biofouling from settling, but instead the slippiness stops it attaching to the hull. The action of the vessel moving through the water is sufficient to detach biofouling from its precarious hold.

A further type of anti-fouling measure is biomimetic coverings. Coatings that imitate the tightly scaled surface of a shark, flock surfaces that mimic plants, or hydrophobic applications based on water repelling surfaces of a lily pad are all biomimetic coatings.