The Rot Doctor


Subject: Cavalier
Date: Thu, 24 Dec 1998

Dr. Rot, I have a 26' Chriscraft Cavalier (plywood construction). The bottom, although surpassingly solid, contains several rough repairs. If the bottom is completely dry and clean, (the boat has been inside and open for over a year), would it be "ok" to overlay with new plywood or fiberglass, to both strengthen the bottom and provide a smoother surface for painting? I am new at the boat repair thing (as you can probably tell by my question) and any advice would be appreciated.
G.S. B.

Well, in my opinion the fiberglas is out. I don't like it over wood on boats that were not specifically constructed to receive it, and neither do most marine architects and surveyors. It invariably leaks and water gets between the glass and the wood and you have a great potential for rot, which you cannot see because of the glass.

Another layer of wood is possible, but not an easy job. It would have to be attached with both screws and an epoxy adhesive, such as our Tropical Hardwood Epoxy Adhesive. The new wood should be soaked after cutting and before application with our Clear Penetrating Epoxy Sealer (CPES). You might get by with a high grade exterior ply, but a marine ply would be better (fewer gaps and more layers), and I can tell you marine ply is expensive. The new wood, even if only 1/4", would add weight to a hull not designed to carry it. Doable, if you want to take the time and spend the money.

Is the old hull really that rough? Would the judicious use of a belt sander smooth things out, along maybe with a bit of Epoxy Filler here and there for gaps and cracks? That would be my approach. Take the hull down to wood, smooth it with a sander (belt or big orbital), coat it thoroughly with our CPES for wood protection and as a base coat for final finish, fill any gaps with our Epoxy Filler, and then paint as desired. This way you are preserving the wood that is there and keeping the boat weight where it is supposed to be. The bottom is plenty strong for all normal usage -- assuming that the interior structure is basically sound.

If there are further details that I should know about, come back and I'll do my best to answer them.