E31 - Antifouling paint recommendations for warm saltwater

[David Vaughn]

Two winter/spring projects are looming ahead, the bigger of which is new bottom paint. I know, I know, this is kinda like asking what the best anchor is, but here we go.

Kotona has been in fresh water for the past twenty years or so. She was due for new bottom paint when we bought her in 2022. But the combination of procrastination and family health issues, means she is now badly in need of new paint. So my plan is to take it back to the gelcoat (or barrier coat if there is one) through a combination of chemical removal and sanding. Then grind out and repair any blisters, fair, barrier coat and paint.

Given our November destinations of warmer waters (Gulf Coast, Keys, maybe Bahamas), I'm hoping for some suggestions based on experience in similar waters. I've found a recent test from Practical Sailor (late 2024), that was performed in the Chesapeake Bay. The article mentions how much less salty than seawater it is and growth slows as temperatures drop, so I'm not sure how much I should rely on their results.

Any actual experience and or words of wisdom are appreciated.

 

[Pete the Cat]

I am going to sound the alarm on barrier coating again. If you do not have the time to completely dry out the gelcoat (can take months on the hard) putting a barrier coat over a moist hull can lead to blister problems. I spent $14k peeling the bottom of my Tartan after a well known boatyard plastered barrier coat over a wet hull and generated thousands of blisters. Most yards seem to have learned that most blisters are between the substrate and the gelcoat and some of that moisture can come from the inside if the hull has absorbed anything--and most hulls kept in the water have. Your actual choice of bottom paint is sort of personal in my book. I used high copper hard epoxy paints in my years of cruising because I could dive and clean them and they lasted 2-3 years. I use softer more ablative paints on my seasonally used Tartan--I buy what the yard uses because they have local experience. I have a friend whose boat is seasonally used in Maine and paints annually with the cheapest stuff and seems to have no more issues than I for the short season. So the answer is different, depending on how you use the boat and where you live.