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Patching a FG Boat

Discussion in 'Wood and Canvas' started by Chip, Jan 17, 2005.

  1. Chip

    Chip Curious about Wooden Canoes

    Hello WCHA,

    I'm new here, and new at wood boats. I always avoided wood boats due to my feeling that boats should be played in, not worked on. Then I paddled a 20 ft., Templeton built by Doc Blanchard, sometime around 1970, I'd guess. It was a lovely thing to paddle, but in obvious distress as I had to take bailing breaks about once an hour. Odd turns of events have resulted in this boat coming into my workshop. Now, I need some advice and info. What a pity WCHA lost its archives, because these questions have probably been asked and answered before.

    The canoe is fiberglassed, and my info is that it has always been fiberglassed. There were some obvious breaches in the glass, and extensive whitish discoloration where the glass had separated from the wood. I read here and elsewhere that FG is undesireable. However, my objective is to get this boat back in the water with minimal investment of time and effort. The original glass made it this long, so my partners and I decided to patch rather than strip and replace.

    We've stripped the old glass off an oval about 3 x 8 feet in the center of the hull. This area probably was the "contact patch" during a lot of rocky beachings. Beyond that, we sanded FG down to wood on three other spots that were obvious breachings. That is the extent of the areas we intend to patch.

    1. There are gaps between the planks in the stripped area. Do we need to fill, and if so with what?
    2. What weight FG cloth should we use?

    My feeling is that much of the deteriorated area was the result of water intrusion from the inside of the boat, and this needs to be addressed. This looks like a nightmare, due to the irregular surfaces the ribs and planks present. Do we need to strip and sand? Do we need to do this before continuing with the fiberglass shell? Is there any easier method to do this?

    Thanks for any advice,
    Chip Walsh
    Gambrills, Md

    Patch Area
  2. Todd Bradshaw

    Todd Bradshaw Sailmaker

    If the boat is that old, it would have been fiberglassed using polyester resin, which can be both good and bad. It's good in that it is substantially easier to remove than epoxy resin. It's bad in that it doesn't stick well to wood or seal it very well. All those streaks and spots in the photo which look greenish are signs of water getting between the glass and the wood and telltales of eventual doom for the canoe unless it's repaired properly.

    In answer to your specific questions, the bottom area should get two layers of 6 oz. fiberglass woven cloth and if you want that part to last, it should be applied with epoxy resin. The two layers should be applied in one shot and should lap a couple inches onto the surrounding fiberglass. Epoxy will stick to both the old polyester fiberglass and the wood better than more polyester resin will. If you're expecting to paddle rocky streams in this big boat, you might want to go up to a fabric in the 7.5 oz. range for more durability. After the cloth is stuck down, saturated and squeegeed down tight, let it cure until it stiffens up. Next, start rolling additional coats of resin over the area to fill the cloth weave. Apply new layers as soon as the previous one is stiff enough to stay-put and add layers until the weave texture is completely gone - then add one more coat. Let it cure for a couple of days, sand it, feathering out the edges of the patch and you're ready for paint. If there are obvious cracks betweem the planks, they will need to be plugged before glassing. Otherwise the resin drains through the cloth and it leaves what looks like screen wire over the gaps. These are extremely hard to get closed-up properly. It's better to plug the gaps before glassing, either with some thickened epoxy, temporary putty from inside or even duct tape - anything which will keep the resin from draining all the way through.

    That's how it should be done and it will yield a canoe with at least a 3'x8' oval area on the bottom that's reasonably durable with proper maintenance. Unfortunately, the same can't be said for the rest of the boat. There is no doubt in my mind that such a patch job is a mistake. If this really is a nice canoe it doesn't take an awful lot more work to fix it properly with canvas so that it will last for a lot longer - and just to be sure you understand what you're dealing with, a fiberglass covered rib and plank canoe may have a slightly more abrasion resistant shell than a canvas covered one, but is actually in many ways more fragile and requires more meticulous maintenance than the canvased one.
  3. OP

    Chip Curious about Wooden Canoes

    Thanks Todd

    Thanks for the information, Todd.

    I'm really torn about the glass vs. canvas issue. Thanks for increasing my angst:) But I've got two partners in this project, and they are set on patching. I loved paddling this boat (which I suppose is the most important thing), but I don't know if it makes the "really nice" grade. Probably not. The seats and thwarts are a jug-a-lugga collection of dissimilar parts installed in dissimilar fashion. I think if I set out to have a really nice boat, I'd start with something other than the present project.

    How about the inside of the boat? What's the most practical way of making it watertight on the inside?

  4. Todd Bradshaw

    Todd Bradshaw Sailmaker

    It's not a great idea to use most chemical strippers on the inside of a fiberglass-covered wood canoe to remove old varnish as anything which seeps into the cracks between the planks can attack the resin and mess up the glass skin. There are some strippers which are safe for use on fiberglass, but you can create another problem if you use water to wash the stripper goo off of the wood. It's just asking for water to get down into the wood and that's bad for the glass-to-wood bond. This leaves sanding (ughhh) as the only really good means of cleaning out old varnish, which you'll find pretty tedious. Once the surface is down to either clean wood or varnish that's still reasonably sound, you can re-varnish the inside. There really isn't a better alternative to varnish unless you want to paint the inside. Epoxy makes for a thick lumpy coating and isn't a good option (it also needs a varnish coat or two anyway, to protect it from U.V.). The greatest weakness a fiberglass covered wooden canoe has is that the inside varnish needs very careful maintenance to keep water from soaking the wood and delaminating the glass, so maintenance will be critical.

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