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Re: S&G: 90 degree corners
In Response To: S&G: 90 degree corners ()

: I am starting to build a three section S&G take-a-part kayak.
: Where the sections separate (double bulkheads), I would like to
: have 90 degree edges to minimize any disruption of water flow
: down the hull.
: I have wrapped light fiberglass cloth around an eighth inch curve
: but with difficulty to keep out air pockets. I am wondering how
: to get full water proof fiberglass edges to protect the wood on
: my sections without any air under the glass.
: Any ideas will be appreciated.
: Randy

One way to assist the cloth behave itself is to dry fit it, pulling it tight by using masking tape to anchor the loose edge down. For example in your case, you could lap the dry glass over the corner from the hull onto your bulkhead, pull it tight, and tape it to the bulkhead, say a couple inches in from the edge. If you also pull the glass over another piece of tape on the bulkhead, and apply epoxy only just onto this tape and not further, you can fold and trim at the edge of that tape once the epoxy sets up green.

If your hull/deck has concave sections to be glassed at the same time, you may have to epoxy most of the hull/deck prior to taping the loose edge to your bulkhead. Otherwise the tension on the glass at the bulkhead could pull the glass off the hull at the convex sections. Once the concave sections are epoxied to the hull, you should be able to put enough tension on the glass at the bulkhead to lay the glass tight to the corner.

Bill is right though, no matter how you apply the glass to a sharp wood corner, you can't expect the result to be very durable. The sharp corner with wood under the glass will be easily damaged. It may be best to start with a radius, fill it to a square corner with a glass fiber/cabosil mix, and then apply the glass. The hard underlayment would make the corner a lot tougher than it would be over wood. If I were going to do this, I would round one corner first, assemble the two sides with packing tape applied for a release layer on the un-rounded corner, and then fill the resulting trough with the epoxy gipe. When the epoxy sets, round the second side and repeat. Just make sure that the release tape is applied well inboard of where you are applying epoxy, or you may end up with a one piece boat after all. :) As noted elsewhere, this will leave you with an obvious seam which will mean painting the hull if this bothers you.

One final note, if you haven't given up on me yet - if you do the epoxy fill on the corners, you could glass up to but not around the corner while the epoxy gipe is still green. This will give you a chemical bond, and a totally waterproof and durable corner without actually wrapping the glass around it at all. If you are careful about how well your hull assembly indexes, you could end up with very tight smooth transitions between sections.

So, just curious, what adventures do you have in mind with your take apart boat?

Good luck,

Best regards,

Allan Edie