Wooden Boat People
By McKenzieDriftBoat.com
Help with sealing checked plywood
Hello,
I finished my plywood boat with lots of teak oil. I oil it every year and touch up the Coat-it sections on the bottom. Unfortunately, the boat had one bad winter and I left it in the sun too often, as well. In the first runs of the season, the water comes in through the sides, until I get enough oil in it.. or maybe it's just swelling and tightening up?
Can/should I spar varnish over this? Should/can I epoxy, without stripping the finish, if that's at all possible? Should I just keep pouring the oil to it?
Many thanks! Ken
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Replies to This Discussion
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Permalink Reply by Rick Newman on
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Ken, do you have any pictures? If so do you have them at the inside chine log? Can you see weeping of water through the plywood? Is the teak oil the finish on the outside of the boat? Is it Douglas Fir?
Rick Newman
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Permalink Reply by Ken Shindledecker on
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The water's seeping through the Doug Fir plywood sides, just front of the passenger seat. I've soaked the wood on both sides, with multiple coats of teak oil and it appears to harden, like a varnish.
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Ken,
I think that you are correct about your boat swelling up to keep from leaking. Have you checked the wood to see if it is soft or perhaps internally rotten?
My idea if it were my boat would be to thoroughly dry it out, flip it over to make it easier to work on, sand the outer surface lightly to provide tooth for epoxy to grip it and apply a primary coat. When it is tacky you can then drape a pre-cut layer of 4 or 6 oz fiberglass and coat it with more epoxy, working it in to the cloth. Let that dry for no more than about 60 hours so the epoxy can chemically bond (most epoxies seem to have a 72 hour open window for reapplication) and fill the weave. It might take a coat or two. Let that dry as recommended by the epoxy manufacturer and then sand the surface to smooth it for the application of paint or finish.
There are numerous debates that can be found using the search engine to help you decide on paint, what type, what color or on varnish, what brand, how many coats, etc.
In my mind you will have provided a better, much less porous surface than the Douglas Fir treated only with the oil. The oil treatment can probably be continued on the interior surface. However that is also debated by many!
Rick Newman
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Thank you! So, it's possible to epoxy over a hardened-oil surface, as long as it's roughed up? And can I make it have a satin look? I don't like the shine, so much. I did my boat, originally by mixing stain in the oil to get a dark golden oak main body, with dark reddish-chocolate trim. The main body's darker now,, but I can live with that. I probably want to remove the UHMW shoe and cover that in glass and Coat-it.
Thanks again! Ken
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Permalink Reply by AJ DeRosa on
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It's hard to imagine that the water is coming through the plywood side panel itself. Even if the surface veneers are checked the interior veneers and the glue that holds it together will stop water. Your leak may be in the chine joint or perhaps a nail/screw hole that holds the rubrail. I have seen both in leaky boats over the years. Is your chine joint sealed with a marine bedding compound under the chine cap? If not then take a good look there for your leak.
Epoxy and cloth will not work over an oiled surface. Paint and varnish will work over oil but not as a leak stopper.
AJ
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Thanks AJ!
Yes, water actually comes through the side panels... I'm not talking the chine.. I do live with that; this is water that is visibly coming through the checks in the plywood.
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Ken, it might be time for a half lap patch. There is a good series that AJ did on the subject. However as AJ so succintly pointed out it might be difficult to get the epoxy to stick to an oiled surface.
Rick Newman
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Perhaps the water is coming up from below and out the inside layer?
Is/Isn't varnish related to oil?.. just more complex. Could varnish fill and harden within the wood?
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The varnish is made partially from a variety of oils. Because the Douglas Fir has both winter and summer growth rings that grew at different rates they have dried and aged at different rates hence the opening in summer growth rings if I remember right. The commonly practiced preventative to checking is covering with fiberglass and epoxy before the checking occurs. Then a covering of paint or varnish to protect the epoxy from UV rays.
If the wood is truly porous enough for moisture to transfer from the outside to inside there is probably more damage than meets the eye but not molecules of water.
Varnish might temporarily harden but will not be a long term solution. A sponge and soaking the boat will probably be less labor and money intensive. Replacing the damaged wood would be the long term solution. Higher labor upfront but if you can get the new wood to adhere to the old, oil soaked wood you should be done with the leaks. Does anyone know if Resourcinol glue would work on the oil soaked wood? I certainly don't. Perhaps AJ or someone else can pitch in here.
Rick Newman
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To get a patch to adhere to oiled wood you need to remove the oiled veneer. This can be done with a router and/or chisel depending upon the size of the area to be exposed. In 1/4" plywood set your router at 1/8" to remove half of the suspect area. Now do the same on your patch material and glue it up.
Kevin and I just finished repairing the 1967 Ostrem boat that Roger gave me for "safekeeping" and to exercise for a few years before it's enshrinement in the museum. We were honored to have this boat and then a tree fell on it. Woops, so much for safe keeping. The boat was oiled inside and out and had obtained a beautiful patina. We used this "lap joint" method to scarf a "new" piece of 1/4" fir ply to the damaged panel. I'll post some images when I get a chance. We'll have the boat at the show this spring.
AJ
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Man!..... sounds like I should one day, strip it to the frames and gunnels and re-plywood.....
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