Bottom Paint Update

I’ve been aware of Propspeed (a New Zealand product) for many years having been based in Auckland off and on since 1979. Propspeed, is a foul-release silicone coating famous for preventing marine growth on props and struts has always been produced in New Zealand, with reps in different countries.

During the South Pacific cyclone season we’d leave Mahina Tiare, our Hallberg-Rassy 46 in Half Moon Bay Marina’s dry storage facility while we returned to the United States. In April, prior to launching, BoatSpray, the boatyard’s painting company, would paint the bottom with antifouling. Each year, without fail, the manager would try to convince me to allow them to apply Propspeed. I’d decline, saying that we’d just snorkel down to scrub the prop with scrub brushes and 3M scouring pads.

One year we returned to discover that our then MaxProp was glistening with Propspeed’s yellowish silicone finish. When I asked why, BoatPaint’s manager said, “That’s a gift, mate! We know after having it for a season that you’ll be back for a recoat!”

Sure enough, after 10,000 miles of sailing through the South Pacific and returning to Auckland, we were convinced. In seven months we experienced almost no growth and only minor erosion of the coating at the blade tips.

I recently started seeing ads for PropGlide a similar, but less expensive product, made in the US. When I asked the owner of BoatSpray about PropGlide, he said the rep annually visits and that a few of his customers have requested it be applied.

The coatings are very similar, but PropGlide uses an acid etch called PropPrep, applied with a provided towlette. I thought it worthwhile to try testing both, so last April we coated two blades coated with Propspeed and one with PropGlide.

We sailed 10,000 miles during 30 weeks and at haulout, the Propspeed appeared to have been slightly more effective and adhered better.

The painting contractor proposed an additional test, so we had one of our two bow thruster props coated with Micron 77 and the other with Propspeed. The Propspeed did a far better job of preventing growth.

Coppercoat

Last year at the Pacific Boat Show in Richmond, California while making the rounds of the vendors, Amanda chatted with Jim, the very keen and knowledgeable US importer/distributor of Coppercoat.

Coppercoat is a water-based epoxy hull coating into which 98 percent pure copper powder is mixed in. It claims to have the potential of dramatically cutting pollution relating to antifouling paint and reducing costs of annual bottom painting. It rated Poor in a 2011 PS test (https://bit.ly/3ak0hq3), and has not been tested since.

Simultaneously at the show we met Quincey and Mitchell, a young couple who purchased a Peterson 44 that had 30,000 tropical miles on the Coppercoat underwater coating which had been originally applied professionally 12 years earlier in New Zealand. They showed us photos of their hull which they’d recently hauled, and told us that they were purchasing kits to recoat a couple of small areas that were starting to foul. They mentioned that as far as they knew, this was the first time in 12 years the Coppercote had been re-touched, other than scrubbing and pressure washing.

As I’m always searching for the best antifouling coating I asked BoatSpray if they could coat our rudder. Brian Kent, current manager of BoatSpray said that since the importer/distributor of Coppercoat had recently come to the yard to do several Coppercoat coatings, he’d prefer to have him apply it to ensure we’d be starting with the best possible coverage.

The US-importer stresses that it is critical to sand the water-based epoxy after it has cured, enabling the copper, not the epoxy to be in direct contact with the seawater.

Once the Coppercoat was applied by the distributer and cured, we sanded the starboard side fairly aggressively, in accordance with the attached sanding instructions, until it was nearly free of dimples. The port side was sanded lightly.

Our results after 10,000 miles and 30 weeks was that a substantial amount of slime would occur on the rudder. The port side fared well, but by midseason the starboard side had numerous barnacles adhering to it.

Without a doubt, the Coppercoat coated rudder required more frequent sponging or scrubbing than the Micron 77 coated hull. PS contributors Patrick and Rebecca Childress noted that the guidelines for application were hard to match, and this may have impacted performance (see https://bit.ly/3agsuOo). In our case, the starboard side was sanded very aggressively to match the photographs indicated in the US distributors guidelines. The cleaner, port side was not sanded as aggressively.

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As we’re now recoating the starboard side of the rudder I’m curious to see how many years it would take for the cost of Coppercoat to beat the cost of Micron.

Amanda and John Neal spend seven months at sea sailing 10,000 miles a year while leading sailing training expeditions. The have more than 750,000 sea miles combined experience.