Time to start messing with gunwales. As you're all aware by now I'm incapable of doing things the easy way, or even the best way, or many times doing something the same way twice.
Well this time I'm sort of doing the same thing twice. I liked my carbon over cedar gunwales so much on my first Bloodvein I'm going to do them again on my composite. I'm even keeping the same profile with a 1/2" round over on the bottom, which begins right where the gunwales meets the hull on these ~5/8" wide pieces, and a 1/4" round over on the top. The 1/2" round over on the bottom leaves no flat ledge to hold water when the canoe is inverted. So instead of all the water flowing along the ledge until it hits your hand and then running down into your arm pit it just dumps out of the boat instead. Very nice.
But I remember what a pain in the arse those were so I want to try something different. The first time I used a single piece gunwale and epoxied it to the hull before wrapping it with layers of kevlar, carbon, and fiberglass tape. Then I vacuum bagged the whole assembly. It was a lot of work and and the release fabric wrinkled on the inside curve and left me with a lot of cleanup work. Sand, epoxy, sand, epoxy, sand, epoxy, etc.... It's very difficult to keep a straight edge when using the carbon tape too. I'd like to avoid all that hassle this time.
So I'm going to do separate inwales/outwales and form them off the canoe. This will let me use carbon sleeve instead of tape. And I'm going to try to set up some forms so that after cured they'll have the correct, or nearly correct, shape. I'm guessing that once the carbon/epoxy has cured they won't do much bending.
To compress the carbon sleeve against the cedar gunwales I'll be using heat shrink tape:
http://www.shrinktape.com/products/hi-shrink-tape/hi-shrink-tape.aspx
It's a lot less money than shrink tube (about $21/100yard roll) and I'm hoping will be easier to install (how do you get a 17' piece of heat shrink over a goopy wetted out gunwale?) and that it will handle the curve well.
Last night I did a short test piece and it came out very nicely:
20160202_008 by
Alan, on Flickr
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Alan, on Flickr
The shrink tape went on well, pressed out the excess epoxy (between the overlaps) and left a nicely filled weave and glossy surface. The lines from the tape are visible but after a light sanding and coat of epoxy I think they'll be gone.
Today I had the afternoon off with a big storm hitting so I decided to go full scale and spent the day in the shop getting ready:
Here's the contraption:
20160202_002 by
Alan, on Flickr
20160202_003 by
Alan, on Flickr
20160202_004 by
Alan, on Flickr
Between the shape of the clamps, hull, and forms I was unable to clamp them directly to the hull. So instead I used the clamps as stops and then tied the forms to the hull to keep them in place.
Then I had to build a clean place where I could wet out an entire gunwale. Just a couple 8' pieces of 1/4" melamine with 1x2's screwed to the edges:
20160202_001 by
Alan, on Flickr
The sleeve went on nice:
20160202_005 by
Alan, on Flickr
Then wetted out, clamped to the forms, and shrunk the tape:
20160202_007 by
Alan, on Flickr
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Alan, on Flickr
Ideally you'd clamp to the forms to bend the gunwale before wrapping with tape but I think that would be nearly impossible and incredibly tedious. Wrapping the roll around the pieces takes FOR-EV-ER. Much quicker if you can hold the roll in place and spin the piece.
I'll see what I get tomorrow, or maybe the day after, but at this point I'm not terribly hopeful. After bending the gunwale into place and shrinking the tape it tended to bunch up on the inside curve. This section is tough enough since it's flat (tape puts pressure on corners instead of the flat surface). At least this is the edge that will be epoxied to the hull so looks don't matter. The visible surfaces look pretty good for the most part. There are still some small wrinkles in areas, due to bending after wrapping I believe, so I think I'll have some smoothing work ahead of me.
I'm curious to see how much flex the piece retains and how much the carbon contains the wood's "spring-back" after it's removed from the forms.
Alan