The Basics of
Ablative paint is a generic term for a family of self-polishing paints that come in three different types:
Sloughing paints are the most inexpensive and lowest performing ablative paints. Sloughing paints are designed for single season use only and utilize a soft rosin binder with low copper content. Since they are designed to wear away by water movement across the hull, they are not recommended for vessels that get minimal usage. Additionally, due to the soft rosin binder, they should not be used on vessels that travel over 10 knots or will be in water longer than 4 months at a time. Sloughing paints also have a short paint-to-launch time frame so they should not be used on vessels that are dry stored or trailered.
Ablative paints, like sloughing paints, self-polish when the vessel is underway, shedding layers which release new biocides. They too are generally considered single season paint only. Unlike sloughing paint, ablative paint will last considerably longer, up-to 16 months, and maintain a smoother surface during its usable life.
Copolymer paints, also know as Ablative Copolymer, function like the controlled release of a dissolving tablet, reacting with the surrounding water as its primary mechanism for releasing biocides. These paints maintain a completely smooth surface texture that reduces drag on fast moving hulls. Copolymers have a service life up to 36 months and can be applied in the fall, dry-stored for winter and launched in the spring without degradation to the paint's performance. Unlike other antifouling paints, copolymer paints may be used on trailered boats and boats that are rack stored. These paints last multiple seasons and remain effective as long as their coating is visibly present. The paint requires minimal surface preparation and can be applied after removal of loose paint and light sanding, making these paints the easiest to apply and require the least maintenance.
Hard paints are generally more economical than ablative paints and work by maintaining a hard, durable coating designed for single season use only. Hard paints are an excellent choice for vessels that will be regularly beached or work boats that will be dragging traps, pots and lines up the side of the vessel. Since hard paints do not wear down with use (i.e., polish) like an ablative paint, paint build-up can result from insufficient surface sanding prior to painting. Hard paints also need to be applied and cured for a specified amount of time before being launched, and cannot be dry-stored or used on trailered boats since the biocide becomes inert with long term exposure to air.
After the U.S. ban in 1995 of TBT (tributyltin) as a biocide, conventional bottom paints began utilizing the safer and highly effective cuprous oxide alternative as the primary mechanism to prevent invertebrates/barnacle fouling. An additional biocide, which acts as a supplement to the cuprous oxide, referred to a “booster” or “boosted”, is the addition of zinc pyrithione or zinc omadine to the formulation. To prevent slime, algae and plant fouling on vessels, advances in bottom paints utilize a slime control agent which is typically a proprietary formulation that blocks UV light from coming into contact with the hull's surface. Because barnacles are less likely to attach to hulls if slim and algae are not present, the utilization of both copper and a slime control biocide simultaneously provides the most effective antifouling protection for the hull of your vessel.
Aluminum hull vessels typically should not use conventional cuprous oxide based antifouling coatings due to galvanic incompatibilities of the aluminum and cuprous oxide. The preferred coating contains a modified copper called copper thiocyanate, which has become the industry standard for underwater aluminum as an antifouling coating. This white powdery compound is galvonically compatible with aluminum hulls and aluminum out drives, is safe and effective for use on all types of hull materials, and is available in bright color spectrums including white and yellow.