This might be more a designing trick, but this frame jig of a square of plywood with some slots and carriage bolts and wing nuts allows you to alter the beam and flare of a hull without rebuilding anything. It works really well. I made it because I was unsure of the frame dimensions while building the prototype to Daydream - turns out I left them as I had drawn them - but it is reusable!

Then I pierced the ply by dropping it on my table saw and cleaned up the slots with a saber saw.

Eight 2" 1/4" /20 carriage bolts, 4 short lengths of 1x2 and two side pieces of 1x3 & 4 clamps, and there you have it. You can adjust the width at the sheer, the chine and the flare angle. 

I made two so one could be used to simulate the transom. Computer images and paper models are nice, but when it comes right down to seeing if your materials want to take the particular bend you're requiring of them - nothing beats playing in full sized 3 dimensions.