Builders' Forum Archives
hatch hole reinforcements
Posted by LeeG on Jul 19, 2004
just checked the New Kayak Shop Book for hatch construction on a Chesapeake where it shows three spring clamps being used to attach the sheer/sheer strip at the front/back of the aft hatch.
When I saw reinforcement strips attached exactly as shown in the book with three spring clamps that one piece of 4mm reinforcing ply ends up being attached in only three places with air gaps in between where the clamps are unless a LOT of goop is applied. Five clamps would be better and it'll take long neck C-clamps to reach farther than the spring clamps can reach to the sides. Prior to the existing hatch hole reinforcemetns that cover the entire edge of the hole that one strip was all there was to reinforce the deck. On the two demo boats where the hatch/deck broke it was possible to rip the rest of the hatch strip out by hand as it was insufficiently attached. Another demo boat, an LT18, held up fine to a few rescues because the lone reinforcing strip was securely attached. After the experience of seeing the two original boats decks crack with broken reinforcing strips I went back to all the demo boats and looked underneath finding some with gaps and some where the strip could be popped right out with a strong whack on top while prying it out by hand. I suspect some of the decks were put on with a medium speed cure for the sealing coat and there was a slight amine blush, when hatch reinforcement strips were put on there must have been some amine blush preventing a bond because the strip popped out with thick epoxy on it with a perfect mold of the wood grain on the underside where it came out. So even if you're using no-blush epoxy it's worth sanding that area being glued. If medium cure epoxy is used to seal the deck underside then wiping the area with a wet rag prior to sanding is necessary since the underside will be long cured by the time you get around to cutting hatches.
In Response to: Re: hatch hole reinforcem by LeeG on Jul 18, 2004