Hi,

I am not sure I would listen to me because I have never built a S&G yak, only strippers.  But on a stripper, you get a little spring back, but not much.  It has never been enough to worry about if you are using outside straps to hold it, and if you are going invisable then I recomend installing ribs incorperating the hooks into them.  It is what I did on my Redfish King and I got the idea from someone else, and she (Nancy) got it from "Bear Mountain" I think?

You can check out how I did it both ways at http://kayakkev.wordpress.com/category/wood-kayak/

KK

In October, you've probably completed the work. 

Instructions for the Shearwater Double include cutting the deck before glassing, building a shelf under the deck before the deck is attached to the hull.

And yes, use the cutout for the hatch.  if the shape isn't right, epoxy a smaller similar shaped piece of ply inside - just make a jig to get the bend correct.  support on the sides and a tool box made the correct bend for me.

I was really worried about the process but the cuts and the under shelves look great.

I put down blue 3M (easy off) masking tape,  marked the shape to cut (straight across the gentle deck bend, 1.5 in radius curve to meet with the "sheer" panel (long flat panel on the deck side - see the photo at clcboats.com). 

Drilled hole big enough for saw blade.

Used saber saw: Skill 4470 variable speed at fast, orbital action 4 (lots).  fine blade.  A friend held the kayak (deck and hull strapped together, not attached.  With safety glasses I held the saw up high to guide it from the front pulling toward me so I could see the line.

It was easy to follow line, just not pull hard.

I haven't funished attaching the hatches.  Probably with straps, plus attach the hatch to the boat.

Insulation Foam will seal the hatch.

good luck, Craig