Re: interior glassing

Posted by LeeG on Nov 23, 2006

I don't know the glassing schedule of the Shearwater but most four panel hulls I've run across eventually have glass on both sides of a wide panel that can get impact on the outside with a tendency to a little more glass on the outside for abrasion. Which means at least the cockpit interior bottom hull panels being glassed on the inside and possibly extending into the compartments.

What I have seen with lots of glass on the outside of the bottom hull panels if there's an open area of unglassed yet sealed interior bottom panel in the cockpit that eventually small cracks develop with waterstains showing up in the wood. With at least 4oz glass it doesn't happen.

It's possible to come up with a variety of permutations for glassing and joining adjacent panels, everything from pre-glassing hull panels and joining with tape to combinations of small fillets and glass cloth or small fillets and tape. The Arctic Hawk kit doesn't even have glass joining the interior of the side/hull panels near the midsection, only thickened epoxy. It does have both sides of the panels glassed.

s&g kayaks have been made with only 4mm ply with interior joints held by 1 1/2"-3" 6oz-9oz tape on the interior seams and cloth on the outside. They hold together fine until a particular threshold of impact is met and you hear cracking of the wood. With glass cloth on the interior mid-section there's less cracking, with cloth under the aft deck and areas of high stress there's even less cracking.

High quality 4mm ply is strong but a hard/brittle sealing coat doesn't provide adequate strength to prevent waterstaining cracks from average use.

If you're building for a 200lb paddler and rough use putting 6oz on both sides of possible impact/stress areas pretty much takes care of everything.

In Response to: Re: interior glassing by gilles from France on Nov 23, 2006