Subject: Floor replacement on 19' runabout
Date: Wed, 08 Apr 1998

Martin E. wrote:

Thanks for the tip, Looks like I'll be cleaning out all the old ply except for the bow area and replacing it. The stringers also look rotted forward of the stern. It seems the whole cavity was wet with no way to dry out. What would you recommend for ventilation? I'm thinking of some stringer notches for drainage and air flow. Along with new foam that is raised slightly off the hull.

Martin:

Ventilation and stringer notches and such are great to help prevent wood deterioration, but the most important thing you can do when you're re-building is to protect the new wood and the exposed old wood so it won't rot. I know we're prejudiced because we sell the stuff, but the Clear Penetrating Epoxy Sealer (CPES) is your best initial protective measure. We've been using CPES for years on really badly decomposed wood with very good results.

It's my belief that too many people encapsulate wood with standard epoxy and polyester resins/cloth with the thought that once done, the wood will last forever. Doesn't work, unless done VERY carefully under controlled conditions with just the right wood. Water eventually gets in and then you have a perfect enclosed environment for wood rot: air, moisture, heat. This why I suggested in the post that you DO NOT enclose your new wood in standard resin or cloth/resin, but saturate it with our CPES (especially the end grain), and then varnish (use a polyurethane based varnish) or paint it. The CPES allows the wood to *breathe*, as do most paints/varnishes, and so it can dry out during good weather. It's this kind of *cycling* between wet/dry/warm/cold that keeps the rot fungi from finding an environment they can live in.

As for your deteriorated stringers near the stern, if you can dry them out then the CPES can repair those as well. Assuming that there is still wood fibers there, you can drill some holes, dry the wood, and then inject the CPES. If there are gaps, then come in behind the CPES with a little of our Layup & Laminating Resin. It will restore the wood.

As for overall ventilation, the more the better. Your idea for the notches etc. are good and you should do it. DO NOT COVER THE BOAT TIGHTLY WITH A COVER! If you want to cover to keep rain out, use a tarp or cover with loose sides so the wind and air can move around inside. I see these new boats with the tight covers and I just know that underneath all that there is dampness and heat and unprotected wood -- perfect for rot. A couple of years later the owners wonder why all their wood has rotted.

Come back if you have more questions.

Doc