How it Works: How to Paint your Bottom

There’s no better way to turn your boat into a Chia Pet than to use the wrong antifouling bottom paint.

Back in the day, clipper ships went through an elaborate process to keep marine life from growing below the waterline and worms from boring into the hull. First they laid down a layer of felt soaked in tar. That was then covered with a thin layer of pine and finally, the undersides were sheathed in copper.
Over the years antifouling paints greatly simplified matters, but since they tended to be tin, mercury, or lead-based, they wreaked havoc with the environment and, at least here in the United States, those heavy metal paints were eventually outlawed.
Today, according to Phil Hale of the Martha’s Vineyard Shipyard in Vineyard Haven, there are basically two types of antifouling paints favored by recreational boaters: hard paints and ablative paints. Both contain copper, which is less harmful than the heavier metals.
Hard paint is just that – very hard surfaced. But unless you’re looking for extremely high performance, Phil suggests going with an ablative paint. 

Ablative paints slowly wear away as the copper dissolves, thus continually exposing new copper. Since the paint literally dissolves over time, it eliminates much of the scraping and sanding often required each spring with a hard paint.
There is, however, a relatively new alternative to these copper-based paints. It’s called E Paint and it’s manufactured over in Falmouth. E Paint contains no copper. Instead, it photochemically generates minute levels of peroxides, which make the surface inhospitable to fouling organisms.
Dave Grunden, Oak Bluffs shellfish constable, claims to have used E Paint on quahaug rafts and scallop spawning cages with no adverse effects on shellfish larvae.
And Mal Jones of West Tisbury conducted a bit of an experiment on his own. He painted half his boat, Sanderling, with a traditional paint and half with E Paint. After two years, the E Paint and the copper-based paint have performed equally well.
E Paint costs about what a high-end, copper-based paint costs – around $160 a gallon. Two drawbacks, Phil Hale says, are that it shouldn’t be applied in weather below fifty degrees, and only in dry conditions. This makes it tough if you want to work over the winter, but if you’re like me and you like to do your prep work on a warm day in the spring, E Paint – easier to look after and easier on the environment – may be just the way to go.