My boat has been in the water for three years. How long should I let the hull dry before applying a barrier coat?
Tom Wood responds:
Don't you just hate these decisions? We know, of course, that the longer the boat dries out, the more assured you are that there is little, if any, moisture remaining in the laminate. Putting an expensive epoxy barrier coat over a wet hull is fruitless and may even accelerate the damage, according to several studies. On the other hand, you have a large investment in your boat, and it hurts to lay it up one day longer than necessary to do the job—after all, we own the boats so we can go sailing, not pay additional lay-days in the yard.
If you keep your boat up north, and normally lay the boat up for winter anyway, the question is moot—put the barrier coat on in the spring. If you are in a more moderate climate, but have other plans for the holidays that preclude using the boat, then this time could be used for the same purpose. Lastly, if your boat is enviably down south in the tropics, you're faced with days of beautiful breezes, sun-splashed water, and star-studded evenings ashore while you twiddle your thumbs and watch the hull dry.
The key is patience in this latter case. The longer the hull dries, the better your final result will be. For a boat that has been in the water for three years, three weeks of good weather is about the minimum. If the boat has picked up a lot of water, the process can take as much as six months. But whatever it takes, don't try to rush Mother Nature—make sure she is completely dry before sealing the bottom. Good luck.
