Welcome to the club.

I've almost finished my guillemot S&G. I am just playing around with a hatch and bulkhead before doing some serious sanding and varnishing. I launched it a while back in a fit of spontaneity and impatience. The kayak turns nicely when stationary, yet tracks well. I weigh 95 kg, so the kayak was probably down on its lines, but felt secure, predictable and was a really nice fit. Being a S&G it is light, so my poor old wrecked back can cope with getting it to and from the water. And man the design is distinctive (I fancy that it is really eskimo-ish) - I reckon all the local seals are starting to get very nervous - and I am in New Zealand and the local seals would never have seen an eskimo!

As for building it, it was fun and not that difficult at all. But forget 1/4" ply. I think a super human effort went into George McQuades 1/4" ply guillemot (from reading between the lines of his journal). I made mine out of 1/8" ply and had absolutely no problems in getting the ply to twist to those radical shapes. Initially the panels seemed unreasonably floppy, but once they are stitched and glued the kayak is more than adequately stiff and strong. Covering the kayak with a layer of cloth inside and out makes it way strong enough and gives you the scratch resistance that you are going to need for all those beachings etc...

Darren Neufeld made a really nice Guillemot S&G just out of 1/8 doorskin ply - I think he even got them for something like $8 a sheet. But given the time to build the kayak and the cost of cloth and epoxy, the ply costs are insignificant so my advice is to get the best quality 1/8" ply you can lay your hands on.

Good luck

Pete