What Type of Bottom Paint is Best?
The hull of a boat is a vital structural component. It must keep water out to keep the vessel seaworthy. Barnacles, muscles, sea plants, etc. can attach themselves and compromise the hull. Applying antifouling paint helps slow the growth, making it easier to detach them. If your boat spends little time sitting in the water and is dry or trailer stored, bottom paint is not required. If you choose to bottom paint, then a Copolymer ablative is the best option. It is a softer, self-polishing paint that contains biocides. The movement of the boat through the water causes the outer layer to wear away, allowing for the exposure of fresh, unoxidized paint. Once the boat is back on dry land, the paint will begin to oxidize within 72 hours. When you place the vessel back in the water, the process begins again. The constant wearing away of the outer layer prevents flora, barnacles and other sea life from attaching to the hull. Ablative paints are not suitable for speedier boats as the process would be expedited resulting in too much paint removal.
For an aluminum boat, paints containing cuprous oxide should never be used. Aluminum safe paints include ones that are copper-free or made with cuprous thiocyanate.
For boats that are kept in the water year-round, a hard modified epoxy paint is your best option. This type of bottom paint does not easily wear off. It is very durable and abrasion-resistant. Hard modified epoxy paint does have a high copper content. Some boat owners choose a compost copper technology (which has a reduced copper content), for environmental reasons.
If your boat currently has vinyl paint on the bottom, then your choice is already made. Vinyl paint can only be applied over previous vinyl paint. Vinyl paints produce a lower friction surface making them popular with boat speed boat and sailboat owners. The speed at which vinyl paint dries is another desirable trait.