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It is generally agreed among those who work with wood and epoxy resin that the bond between two pieces of wood well saturated with the properly formulated resin or glue is exceedingly strong. Sheer tests by all major epoxy manufacturers/distributors have proven that. We ourselves have demonstrated that the bond between an epoxy filler of Layup & Laminating Resin and wood flour and wood previously saturated with CPES and L&L Resin is so strong that the wood will rip before the bond will break. So the solution to our rotten hole is obvious, especially so when you consider that the whole thing would be finally covered with a new rub rail of clear and perfect 6" X 1/4" laminated fir strips.
The process is simple. You can see up the starboard side that we had other rot problems further forward once the old rub rail had been torn away. In this case the rot was into and in a few places through a standard 2" X 8" fir plank. And farther forward than any of these pictures show, it was so bad we just ripped it all away and replaced the plank. What does a 2" X 8" X 28' clear fir plank cost in Seattle? Two hundred and sixty dollars, my friends, delivered to the boat. From Eden Saw, over on the Olympic Peninsula, and a very nice piece of wood it was. Anyway, back to the rot. We pulled all the loose bad wood out with fingers and screwdrivers and chisels until we hit the boundary area between rotted and good wood. Where fastenings were exposed we used a Dremel tool to grind away all rust and debris. In a few areas where the wood was more than just damp, we applied the heat from a 80,000 btu commercial kerosene forced air dryer to the wood for a few hours to get rid of the water. In Seattle, you're almost always fighting rain; we had plastic drop cloths that came down each night for protection. And then all the rotted areas were saturated with a coating of Clear Penetrating Epoxy Sealer. It was injected by syringe and splashed on by brush, as much as the wood would take over about a 1/2 hour period. This was left overnight to cure and then the process was repeated. We gave the CPES two more days to cure out and then applied the layer of Layup & Laminating Resin. This final layer of resin bonds to the CPES and fills in the little cracks and crannies. How much CPES did she take? In the rotted areas around the stern, about a gallon was absorbed. On the frames forward where we replaced the plank, another gallon. Elsewhere in restore/repaint areas, about two more gallons. So about four gallons altogether, retail price $268.36. Cheap protection, I call it. |
We gave the L&L Resin application two days to cure. Then it was time for the "mud", the mixture of resin and wood flour. The Layup & Laminating Resin is a slow setting resin, the pot life being about 1 hour at 72°F. Takes us about 10 minutes to get the wood flour mixed in thoroughly, so there's plenty of time left for application. They key here is to get just enough wood flour in so the mixture will barely "hang"; you want the maximum amount of epoxy resin surface for good bonding. We in fact make it loose enough that we always have "hang" sag and have to go back in finally and fill the gaps. |
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In an area this large, the resin/flour mixture must be applied in several stages. For the first application we concentrate on pushing the mixture into all the back spaces and holes. We use putty knives, screwdrivers and wood sticks - whatever will get it in there. Let it cure overnight. Go back the next day and just bulk it in - big quantities. The third application is a fill and smooth. And finally we use the white Fill-It Epoxy Filler to take care of the gaps. Further forward, smaller cracks and gaps are usually a one swipe application. If there's a hole through the plank, we make a backer plate out of cardboard and a piece of wire, insert it, and then pull the wire taught while the putty is applied. Once hardened, clip off the wire. Cost? About $8.00 worth of wood flour and $150.00 for the Layup & Laminating Resin. After a couple of days the whole thing is ground smooth with #60 grit belts on a belt sander. The wood flour/resin mix is a bitch to sand and on large areas the belt sander or large disc is the only way. In our case, the hard work was done. You can see in the picture the first of eight 1/4" planks that were wrapped around to form the stern rail. These were first nail-gunned into position and then lag-bolted through when the whole 2" thickness was up. And yes, we lagged right into the repaired area. No problems. Just so you know, the new hull plank was coated with the CPES before being wrestled and lagged into final position. The covering rub rail likewise. Took about 2 quarts. That's about $39.00. |
The new stern portion of the rub rail was laminated with the Tropical Hardwood Epoxy Adhesive, and then coated finally with the CPES. About 4 quarts of the laminating resin and another quart of the CPES. So that's $150.00 for the adhesive and about $19.00 for the CPES. I'll let you add all this up if you want to. For us, the comforting thing is knowing that we were using products that are the best of their kind. That patch and the new rub rail will still be there when the rest of the boat (and me) are gone.
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