Its really not very complicated, people!
Get some dimensions (length, width center, width at 12’’ and 24’’ from nose and tail). Crib them off a board that you like or draw them on graph paper (or in a CAD program if you really feel the need to involve a computer).
Then, mark those dimensions on a blank, and stretch masking (preferably a darker-colored) tape between the points, until you get a nice curve. Repeat on the other side- (Hey, if you can’t create balanced curves this way, forget trying to shape them).
Dust the tape edge with spray paint or graphite, and cut out with a handsaw. Yes- a handsaw- it makes the truest curves-under-tension.
Clean up the cut. Make any adjustments the you deem necessary. Yes- YOU- its your baby-no one else is shaping this board!
Now you’ve got an actual, non-virtual hunk of material in front of you, and you will begin to feel those curves.
When you get it the way you like it, trace the actual curve onto a sheet of doorskin or 1/8’’ masonite.
I’ve always cut out my templates with a big wormdrive Skilsaw (I learned this from a shipwright). Using a panel-cutting blade, set at just a hair over the thickness of the template material, which is tacked or clamped to a 8 foot long piece of pine shelving, cut the bulk of the curve with the Skilsaw, and straight-cut the tighter radii, and leave some room for wings and/or bumps. You’ll have to use a handsaw for those areas.
Then, clamp the cut template material to the pine board (which itself is clamped to a worktable or shaping stand) and use the power planer (NOT a sander) to clean up and true up the edge. The planer will maintain the same curve-under-tension set by the handsaw and the skilsaw.
Finish up with a sharp hand plane and a sanding block.
The whole operation maybe takes an hour and a half, and you’ll have both a planshaped blank AND a new template. (and a deeper appreciation of that curve).
Computers are cool, and everything, but part of the joy of making a surfboard (or anything) by hand is the HANDWORK!
[edit] ps. what Ambrose said…
[edit part II] maybe I’m experiencing early-onset geezerhood, but all this talk about beers-per-board and Akus sounds pupule! Its turning it into paint-by-numbers…