Builders' Forum Archives
Re: SH 17 +carbon/kevlar
Posted by LeeG on Jan 26, 2006
Kevlar FELT makes for good skid plates on canoes because it's THICK. Kevlar in thick laminates like Kruger canoes/kayaks work because it's THICK. A 5oz layer of kevlar cloth in and of itself will take longer to abrade through than 6oz e-glass but it'll be fuzzy and require thick applications of epoxy to cover the fuzzies when it does get worn.
The trick with kevlar and abrasion is to have a thick ablative layer...which you can do with s-glass or e-glass and have a more easily repaired laminate. This isn't to say one layer of 5oz kevlar cloth won't be noticably more abrasion resistant than one layer of 6oz eglass. But a significant portion of that resistance is that in hand layups the 5oz kevlar will be soaking up as much resin as a well squeeged 7.5oz glass. I don't mean to sound like a killjoy but if you put 5oz kevlar cloth over the entire bottom of the kayak,,,and have one layer of kevlar cloth at the bow/stern wear spots,,you'll wear through that one layer of 5oz kevlar. The four panel s&g kayaks bring the ends to fine points and concentrate a lot of wear into a 1/4"x6" spot. Putting anything that's thick or hard in that one narrow spot (check out the A.Hawk details) will do more to address where abrasion occurs than applying fancy materials everywhere on the bottom of the kayak. Kevlar,like carbon is fantastic stuff, and works well in laminates where the cloth is a significant part of the panel strength and built with vacuum bagging. With 4m plywood the wood is providing most of the strength with the exterior skin being most valuable for surface durability/compression as well as tension. I built a Ch16LT with 4oz s-glass and 5oz polyster cloth over that,,,I figured it would be a good oyster bed kayak and easier to repair than kevlar. It is but weighed 55lbs with no deck glass. I could have doubled up the bottom with two layers of 6oz cloth for more impact resistance and probably the same or slightly more abrasion resistance using the same amount of epoxy.
In Response to: Re: SH 17 +carbon/kevlar by Bob on Jan 26, 2006