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On 23 March 2024, I returned to the underwater hull. A visual inspection showed no damage, so I planned no fibreglass or filler work.
Broadly, two coatings go on the hull: primer and antifouling. The first protects the laminate against water ingress and osmosis; the second prevents barnacle growth. You can apply fresh antifouling over the previous coat, but ideally the paints should be compatible. Any areas where the old coating has cracked should be primed first.
Primers come in one- and two-component types. Two-component products can go only over other two-component coatings; one-component products are less particular. As I knew neither the brand nor type of the old paint and primer, I followed the manufacturer’s recommendation and coated the entire underwater hull with a one-component primer.
A Practical Boat Owner article comparing paints appeared at just the right time. After reading it, I chose Hempel. They have an excellent website with guides and documentation for every product, and a YouTube channel with videos to accompany the instructions.
First, clean the surface with Hempel Pre-Clean and let it dry, as when polishing. My 29-foot fin-keeler took a litre of Hempel Underwater Primer and three hours. I used a foam roller. The primer went on easily in a thin, even coat. I’d recommend a roller extension pole: much easier on large areas. The specification says that at 10°C it must dry for at least eight hours and no more than thirty days. So I left the yacht another week.
#maintenance
Broadly, two coatings go on the hull: primer and antifouling. The first protects the laminate against water ingress and osmosis; the second prevents barnacle growth. You can apply fresh antifouling over the previous coat, but ideally the paints should be compatible. Any areas where the old coating has cracked should be primed first.
Primers come in one- and two-component types. Two-component products can go only over other two-component coatings; one-component products are less particular. As I knew neither the brand nor type of the old paint and primer, I followed the manufacturer’s recommendation and coated the entire underwater hull with a one-component primer.
A Practical Boat Owner article comparing paints appeared at just the right time. After reading it, I chose Hempel. They have an excellent website with guides and documentation for every product, and a YouTube channel with videos to accompany the instructions.
First, clean the surface with Hempel Pre-Clean and let it dry, as when polishing. My 29-foot fin-keeler took a litre of Hempel Underwater Primer and three hours. I used a foam roller. The primer went on easily in a thin, even coat. I’d recommend a roller extension pole: much easier on large areas. The specification says that at 10°C it must dry for at least eight hours and no more than thirty days. So I left the yacht another week.
#maintenance
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