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Darts, and a bias strip along the keel
By:Paul G. Jacobson
Date: 1/23/2008, 3:47 pm
In Response To: Strip: Glass overlap on sharp keel *Pic* (Steve Beckman)

: I'm currently building Gary Dierking's T2 outrigger canoe, which has a very
: sharp keel from stem to stem, and quite a bit of rocker, as well (see the
: attached image of the forms), and am finally ready to begin glassing the
: outside. The plans call for 6oz glass, and I'll need one piece for each
: side. I'm trying to decide how to handle the keel.

A sharp keel like that is going to be the first thing that hits beaches. Snady, rocky, or otherwise, those beaches will scratch the keel. Obviously, this is an area for reinforcement.

If you have one piece of fabric for each side, and overlap them over the keel, then you should have good protection there. The tight bend of the fabric over the keel is not going to be a problem, but hull curvature may cause the fabric to bunch up. or need to stretch along that keel line. The solution to this is to cut slits, or darts, in the edge of the fabric which overhangs the keel.

Get a good pair of inexpensive scissors. They need to be sharp enough to cut your glass cloth, and cheap enough to throw out. They will get full of resin. If you can't clean off all the resin, you'll end up disposing of these scissors. Do one side of the hul at a time. apply the cloth with about 4 inches of overhang along the keel, and get it smooth on the side of the boat. Start at the center of the boat and work toward the bow, bending the overlap down so it sticks to the other side of the hull. If the fabric starts to pucker, (there is too much there) use your scissors to cut a "V" shape out of the wet fabric. The point of the "v" is right along the keel line. If the fabric is getting stretched, cut a single slit, perpendicular to the keel line, and running right up to the keel line. When you lay down the overlapping glass, the tension will cause this slit to open up, forming an empty "v" shape.

When you glass the other side of the boat, do the same thing. At best you'll have about 90 percent of the overlap areas with a double layer of glass.

Cut some of your excess glass fabric at a 45 degree angle to the weave, and make strips whic are 4 inches wide. This bias-cut fabric will bent and stretch nicely over your keel line, and in extreme areas, you can still cut darts in it for better fit. With the bias strip on the outside, you'll have a layer of glass that can be sanded into, and still have great structural strength.

If you don;t want to play with the overlap, apply the 4 inch bias strip to the keel first. Then lay up the glass for the sides, bringing it up to cover the bias strip on that side of the boat, and cutting it off even with the keel line. The side piece doesn't fold over. after doing both sides, use a sharp plane, or a cabinet scraper to remove any rough edges while the resin is still "green" (stiff, but not fully cured and hard) Then lay a second strip of bias-cut tape down the keel line to overlap the edges, and give a full 2 layers of protection to the keel.

Hope this helps.

PGJ

Messages In This Thread

Strip: Glass overlap on sharp keel *Pic*
Steve Beckman -- 1/22/2008, 2:55 pm
Darts, and a bias strip along the keel
Paul G. Jacobson -- 1/23/2008, 3:47 pm
Re: Strip: Glass overlap on sharp keel
Chris Ayles -- 1/23/2008, 3:15 pm
Re: Glass layout
Mike Scarborough -- 1/23/2008, 10:49 am
Re: Glass layout
Steve Beckman -- 1/23/2008, 2:42 pm
A few tips
John Caldeira -- 1/23/2008, 9:34 am
Re: Strip: Glass overlap on sharp keel
Bill Hamm -- 1/23/2008, 1:52 am
Re: Strip: Glass overlap on sharp keel
Mike Scarborough -- 1/22/2008, 4:14 pm