The Rot Doctor


Subject: veneer over plywood
Date: Fri, 17 Sep 1999

I'm about to dive into a project I know little about. The boat I have rescued from the dump is a '65 chris craft cavalier. About a 16' utility/ski boat with a 283 engine. The hull is plywood with a fiberglass skin. I'm a wood worker by hobby and my plan is to remove the fiberglass skin above the waterline and replace it with a veneer of mahogany. For the deck I may just strip off the plywood and replace it with 3/4" mahogany. I was told that your penetrating sealer is great stuff so I was thinking of letting the plywood have all of it that it will soak up and then letting it cure before roughing it up and beginning the veneer process using the laminating epoxy resin. After I get the laminating finished and the deck laid down I'll go over the whole thing again with the penetrating sealer followed with spar varnish. Tell me if I'm on the right track or how I could improve the plan. How thick would you recommend the veneer be cut? I'll be doing that myself as well.

Interesting project. Those were nice looking boats and a varnished veneer would be lovely indeed.

Some comments:

1) For the hull we would recommend that you use our Tropical Hardwood Epoxy Adhesive to bond on the veneer. This is tough stuff and retains a degree of flexibility that normal epoxy resins do not. It is good for working down to 50F.

In using THEA on clean, clear wood, we suggest that you use the CPES (penetrating epoxy) initially on the old hull seams and joints ONLY. You would apply it with a small brush. It's important for future rot protection that CPES get into these seams and joints. This leaves most of the wood clear to accept the THEA, which will then get the best possible bond to raw wood.

2) After the veneer is down and sanded clean, we then suggest you coat the entire hull exterior with the CPES. In doing this we recommend that you apply the CPES and then after about 15 minutes you go back and wipe down with a clean, dry cloth. This will smooth out the tonal differences in the absorption and produce a smooth, even finish. You should experiment first on a piece of veneer so you know you're going to get the tone you want. CPES produces a very nice tone to wood, darkening it somewhat and highlighting the grain.

3) We recommend that over the CPES treated hull you use a marine-grade one-part polyurethane varnish. It is our opinion that the bond between the urethanes and CPES is stronger than it is between CPES and the oil-based finishes.

4) If the deck plywood is good, why replace it? Three-quarter inch mahogany is going to be a lot heavier. If you have to replace, perhaps something a little thinner -- say 1/2" -- might be more appropriate.

5) If you veneer the deck, we'd suggest the same program as the hull. If you re-plank the deck, then we suggest you coat each piece of wood -- after cutting and trimming -- with CPES before installation. End grain application is especially important, because more often than not this is where the rot gets started.

When you get going and have more questions, ask away. We'll give you all the help we can.