This would be plywood stitch and glue if it matters, but the splines would be curving in 3D.

THEN I'd like to flatten the panels between the splines out, maybe using sheetmetal SW tools, so I could cut plywood. 

But for right now, I'd just like to make 3D splines work to simulate a boat hull shape.

It would be fine if the hull is first a solid shape which I then run a Shell feature on the 'deck' to hollow out. 

Just need the curves on the gunnels, keel and chines.

thx in advance!