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> I am one week into building a Coho. I am in the process of glassing the
> butt joints together. The inside joints are done and I am working on the
> much more visible outside joints. In spite of my carefull glassing and
> covering the joints with acetone, I have a couple of seams where you can
> see the fiberglass tape. The problem appears only at the very edges of the
> seams. I am more worried about the appearnace rather than the structural
> integrity. Can I cut the edge of the tape with a razor? Can I sand down
> just that area? Do I have to re-do the entire joint?
> If sanding is an option, how much can you sand before you sand through the
> first layer of plywood? I am using a ROB sander.
> On a related note, I have noticed in several areas of the Pygmy manual
> where they say do not sand into the fiberglass tape. Will this cause a
> structural problem or an appearance problem?
> Thank you in advance for your help in what will probably be the first of
> many questions.
I came across the same problems as you did when I built my Arctic Tern last winter. I read a post this spring that someone had stitched their boat together, then removed the tape on the exterior of the boat. Pull one corner up by sliding a knife under the edge, and pull the tape off. The tape is really just to keep the boards together until they get assembled, so you won't be losing much strength by doing without them.
If you do some sanding in this area be careful -- if you sand down through the epoxy to bare wood, the wood will appear lighter in these spots. The epoxy that soaked into the wood when you did the butt joints seals the wood down farther than you might think. You will sand down to what you think is fresh wood, but it may have enough epoxy in it to prevent your full hull epoxy job from penetrating later.
In a few areas of the butt-joint tape where I had small trapped air bubbles, I drilled a very small hole through the cloth (not down to wood) and injected epoxy into it with the supplied syringes. This worked very well. I used a 3/64" bit in my Dremel, but 1/16" in a drill should work just as well.
Future hint: Be extra careful in ALL areas where you overlap cloth, whether it be the overlap on the stem and stern, the deck-to-hull joint, or the wear strip on the keel. I must not have squeegee'd well enough, and many of these areas have a sort of a cloudy yellowish look to them. I didn't have a bubble roller at the time, but I've seen them since at West Marine and will definitely be using one on my in-the-works kayak.
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Guillemot Kayak - High Performance Wooden Sea Kayak Designs