Service life is an important consideration for boat owners in controlling costs. If a hull coating is not maintained properly, or eventually over time, water may penetrate the coating, causing it to blister. If that occurs, the hull's surface must be stripped down to the gel-coating, the blisters must be ground and patched, then a new coating must be reapplied.
Durability of the coating, proper hull surface preparation and application are important in extending the service life of each layer of the coating and increasing the number of layers that can be reapplied before coatings must be completely stripped.
Copper antifouling paints are used primarily to control fouling in saltwater. They are designed to slowly leach cuprous oxide so that new copper ions are continually presented to the surface. This discourages spores and larvae from attaching and surviving on the hull's surface. When the cuprous oxide is depleted, so is the antifouling capacity.
In contrast, a nontoxic hull coating is primarily a water barrier (although nothing is perfect). Nontoxic hull coatings are suitable for use in both fresh and saltwater. If they don't control fouling and must be used with a companion strategy, can they be cost effective? Service life is the key.
Our fact sheet, Nontoxic Hull Coating Field Demonstration: Long-Term Performance 2007 Update reports on three coatings that were included in our 2002-2003 field demonstration. The durable, epoxy and ceramic-epoxy coatings had lasted 5-8 years. In contrast, our 2002 survey of 200 San Diego Bay boat owners found that the average service life for copper antifouling paint was 2.5 years. (see our tech report Making Dollars and Sense of Nontoxic Antifouling Strategies for Boats). The economic analysis in this tech report found that nontoxic coatings can be more cost effective than copper antifouling paint, if they have a long enough service life.
For a full report of the 2002-2003 field demo, see our tech report Staying Afloat with Nontoxic Antifouling Strategies for Boats.
The fact sheet and the tech reports are available from the Nontoxic Antifouling Stategies and Publications pages of our website. The fact sheet is also available in Spanish on the Publicaciones page of our website.