Rot Doctor


Subject: Soft wood in 40′ Defever Trawler
Date: Fri, 12 May 2000

I recently bought a 1970 Defever Trawler built in Japan. The boat is very heavily constructed and the pre-purchase survey showed no structural problems to the hull. However, several areas of soft wood were found in the cabin, deck and flying bridge. I would like to be able to repair these areas without the necessity of an extensive (and expensive) wood replacement in the yard. While looking for wood rot repair procedures and products on the net I came across your site and from some of the problems discussed in the Q and A section which seemed similar to mine, thought maybe you could suggest some repair procedures using your products that might save me from taking out a second mortgage to get the boat fixed. The main problems are: 1). Several soft areas exist on the flying bridge chariot sides which seems to be made of 3/4″ ply encased in glass (all soft spots are less than 1′ by 1′). 2). There are sections of soft wood on the toe rails on the bridge deck. 3). Several plywood boxes covering thru deck vents show soft areas near their base (not glass covered). 4). There are soft areas in the 1″ thick mahogany bulwarks where the stanchions are mounted. 5).Several non encased plywood bulkheads show soft areas.

Sure hope you can suggest a way for me to repair these areas with your products. I’ve used “Git Rot” on other boats I’ve owned but from those results didn’t think it would work on a project of this magnitude. Appreciate any suggestions you can offer.

Jim G.


I’m going to answer your questions in a general way. If what I say seems like a path you might follow, then we can get down to specific areas and the specific techniques/products needed for those particular repairs.

The answer to your question is yes, everything you describe can be repaired with our products. CPES (Clear Penetrating Epoxy Sealer) is unique on the market and is widely used for just the sort of deterioration you describe. Our Layup & Laminating Resin, which is wood-derived and is unique in that respect, has some special characteristics that make it very appropriate for wood repair. Our Fill-It Epoxy Filler is less unique, but competitively priced and is easier to sand than many others. All of these products will bond together at the molecular level.

As our website says, we own and use for research/experimentation a 50′ Canadian tug that was built in 1889. She is never short on deteriorated wood, and we have used massive amounts of all our products to keep her going. So what I say is based on many years of experience in using these products.

You are dealing with several separate issues here. Wood (it’s almost always ply) encased in glass requires different repair methods than wood that stands alone. For any of our products to work (and any other epoxy products for that matter) the wood, even though rotten, must be reasonably dry. Doing this can be tricky with ply encased in glass, and we have worked with drilled holes and air pumps to make this happen. Once the wood is dry, then the introduction of CPES into the damaged area will restore hardness to deteriorated wood, “greatly retard” the rot fungi/destructive bacteria, partially waterproof the wood to the point where it can no longer absorb enough water to support biological activity, and encase the wood fibers in epoxy resin. CPES fills micro-vacancies but not large vacancies. Generally speaking, if the wood fibers are still in place — even though rotten — then one or several applications of CPES will harden that wood to the point where it will accept fastenings. In cases where there are larger vacancies, and you are working from the top down, the application of our Layup & Laminating Resin after the CPES will fill large vacancies. The L&L Resin is a simple mix, has a long pot life, thins a little while curing and penetrates larger areas, and always retains a slight degree of flexibility — about the same as good wood. As a general principle, if I am treating an open area, regardless of its orientation (up, down, or sideways) I always apply a coating of the L&L Resin after the CPES. In large vacancies, I allow it to flow in, sometimes mixed with sawdust to increase volume and save on resin costs.

In open areas (surfaces and the like) it is often sufficient to bare the wood, dry it (we’ve used everything from hair dryers to 80,000 btu kerosene blower-heaters), treat it with CPES, allow a day or so for the CPES carrier solvents to evaporate away, and then go back in with the Fill-It Epoxy Filler and fill. Once cured the Epoxy Filler is easily sanded with an orbital sander, and can be painted. All surfaces treated with CPES or the Epoxy Filler can be easily painted, with the products acting as base coats.

Soft wood around fastenings can be easily repaired by removing the fastening, drying the wood, saturating it with CPES, allowing the CPES to cure, filling with a little L&L Resin, and re-fastening. No big deal.

And forget about Git Rot. It doesn’t penetrate well and sets too fast to act as a good volume filler.

I hope this has been of some help. If you want to go further, pick a specific area, do a little poking around to determine the extent and depth of the rot, the condition of the rotted wood, it’s orientation, and we can plan an effective repair for that area.

The problems you describe are fairly typical for a wood boat of that vintage. DeFever is one of the better built hulls.