Bob wrote; I have only launched the boat from knee deep water till this weekend, when I took it to the beach where I "Seal Launched" of the sand into 1 foot seas. The action of flexing the hull from sitting on the sand, then lifting the boat has created huge cracks in the clear gelcote. The cracks are 3 or 4 feet long and substantial enough to have flakes of gelcote fall out. In addition there are other worsening cracks in the the deck above the rear bulkhead. This sounds like a defective gelcote? When I press on the hull, I hear the sound of one hull cracking! (SNIPS) I am not fond of carbon fiber where there will be impact or large localised loads. When it breaks it really breaks unlike Kevlar that has greater tolerance to impact. The problem with many of these hi-tech materials is that they require careful engineering. I remember when Kevlar first came along and people tried to build boats using regular polyester resins. What a disaster! It is important to match all the materials. These days builders are more savvy and use flexible vinylesters and flexible gel coats. Even so, things go wrong. The problem with Bob's boat sounds (but may not be) like a rigid polyester gel coat or maybe even an incompatible gel coat (incompatible with the laminating resin). One really has to see the thing to form a reliable assessment though. I would like to know what resin was used to build the boat and what gel coat. Of course, for the lay person this isn't much help. But at least one should know if the resin was epoxy, vinyl ester or iso or orthopthalic polyester. If it is one of the latter two then I would be upset. Properly built carbon boats are remarkably strong especially when matched to the proper core material and with the fibers properly oriented. Usually they are made from epoxy pre-pregs vacuum and heat cured under pressure. I had a canoe that was built that way and it was truly remarkable. One of the great sins is to use the mixed materials (carbon/Kevlar) cloth. It looks sexy but the result is poor. As Hank Hays says, "Carbon is not all it's cracked up to be" Cheers, John Winters Redwing Designs Specialists in Human Powered Watercraft http://home.ican.net/~735769/ *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************Received on Wed Apr 29 1998 - 06:37:40 PDT
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