Decided to build an SG15 for a bit of exercise and to get out on the water. Liked the size and weight of the SG15- small enough to cartop, but big enough for open water and less than perfect days.
Anyway, got the plans, ordered the materials and made a start.
Here in Australia, we are blessed with some of the highest quality marine plywood in the world. Some people think marine ply is overkill, but I like it for several reasons, mainly consistency of product and the fact you save a huge amount of finishing time buying AA face plywood as you don't have any weird open grain or defects to fill.
I went with locally made Hoop pine plywood instead of the imported BS1088 Wasatree as they couldn't tell me which species of wood it was or the country of origin. Weight was also a consideration, with the Hoop pine being lighter.
I've decided to use 9mm ply for the bottom panel, seat and bulkheads, 4mm for the rest. I'm only fitting one seat and will enclose the bow and stern of the boat from the forward and rear frames at seat height as buoyancy tanks. As I am using 9mm for the bottom panel, I wil scarf those pieces together, but side panels will be butt strapped as I feel it gives a consistently stronger join in such thin ply and you don't get the glass join you need to fair on the outside of the hull like you do with a glass joint.
The 9mm makes for a pretty stiff bottom panel and I can see it adding a LOT of rigidity to the hull. Only issue is that I don't think it'll take the bend it needs to take with just the side panels pulling it into place, so I will temporarily fasten the bottom panel down to my building "table" at mid seat frame and block the bottom panel to the shape it needs to be before I try to fit the sides. With 4mm ply, I am worried about tearing through the ply trying to pull such a stiff panel together.
Anyway, not much progress to look at so far, I have all frames and panels cut out, need to do all the joints on the panels next. I'm only working on the boat a few hours a weekend and in spare time.
