stitch and glue + -

If a sheer plank is very floppy or you worry that the joints between the ply sheets may be at risk, you can stiffen and strengthen it with a longitudinal stiffener glued on while it is still flat. This could be an inwale, a seat riser or a stringer of the existing design.

But don’t overdo it, especially on larger boats, or the plank may not follow the sheer bend. Been there, done that. Stiffness varies as the cube of ply thickness plus stringer thickness. First test a length with the ply thickness added to ensure it will bend enough . . .

 

There are a lot of different techniques you can employ to handle large stock. People are the best way, as they take direction and can adapt to the changing situation. I've used all sorts of aids, but most boil down to just thinking about what you need. A loop of line flung over a hull or frame about a 1/3 aft of the bow can help hold one end up while you clamp the other end. The loop can be turned into a Spanish windlass to draw up the plank or you can build something more complex, like an "A" frame to support the plank. Generally, these things sort the men from the boys, but if you think about what gravity will do, how the plank or panel will want to flex and relax and where you need the real support, things whittle down to a few simple, easily shop engineered options. One thing I've used repeatedly is a "Z" shaped dog that is screwed to the hull of framing, permitting the plank or panel to be hung very close to where it needs to be. You can drive wedges under the plank and/or behind it, to drive it into position, all the while holding it up too.