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Hello there,
I´m not sure, but I think i read something a few month before that I have to use a twart or something to spread the inside of the hull to it`s planned size when sanding and fiberglassing. Is that true? I searche dall my papers for that, but I couldn´t find the it again. In canoecraft there I found no hint as well. So was it maybe just nonsense ( I think I read it on the net at a boatbuilding page, but I have no idea where) ..
Spreader sticks should be used if you have to wait a long time before glassing the inside. How long? That depends on the temperature and humidity of the workshop. If the humidity increases or varies a lot after glassing the outside but before glassing the inside, the hull can warp out of shape. This has happened to some builders and one of them tried to spread the hull back to the right shape and it cracked!
If the humidity in the workshop is constant, and you glass the inside shortly after glassing the outside, the spreader sticks should not be necessary. If you decide to use spreader sticks, you can remove them while you work on the inside and put them back in after doing the work. Do not put the sticks in while the epoxy inside is still wet or sticky.
We cut spreader sticks for Sations 1, 3, 5 and 7 on each end of the canoe. We have kept them in place pretty much all along since we took the canoe off the forms (4 weeks now). We also kept the temp and humidity pretty constant. The sticks don't appear to be doing too much (without them, the station 0 beam only decreases about .5" when sitting on our supports on the strongback). But we've kept them in place "just for good measure".
We took them off while sanding and glassing the inside but put them back after the epoxy had set up.
spreaders should be how wide? cut to the width of a station mold and placed at that location?
do the thwarts and seats and yolk all get cut to the length that matches the inside width of the hull at their location? i would like to be working on them while i am waiting for epoxy set up to complete, but am unsure of the widths to work with.
Thanks!
The thwarts, seats and yoke should be a bit shorter than the distance measured at thier locations so that the ends do not rub against the hull. Angle the ends to match the hull shape on both the horizontal axis and vertical axis. About 1/16" gap at each end is fine.
The angle is just to keep the separation even. By this I mean, on the frames for the stern seat for instance, if you cut the frame ends straight across, you will have a 1/16" gap at the back but a much greater gap at the front of the same frame member because of the spread of the hull. In other words, cut the ends of the thwarts, yoke and seat frames to match the curvature of the hull and also to follow the vertical hull shape (tumblehome or straight).
Refer to Canoecraft (revised edition) photo on page 172. Older edition on page 131.
I believe you could. But they would have a tendency to fall over. You would need to find a way to fasten them to the sheerline. Also, once you start putting inwales in place, you will need to notch the forms to make room for the inwales vs shortening the spreader sticks.
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