: 1) what is the shortest
: length I can safely buy to make strips that will go the whole length of
: the shear?

The distance along the shearline is not significantly greater than the length of the boat. So you would purchase 18' boards for a 17' boat.

: 2) approximately how many board feet is needed to build a
: Great Auk if the boards are planed down to 3/4 inch? Thanks.
: Please respond directly.

Someone may know off hand. Theoretically, if you bead/cove a 3/4" strip then you get 5/8" coverage (1/8" will be concealed on one side of each strip). So, measure the circumference of the largest form in inches with a tape measure and see how many times 5/8" (.625") goes into it. So that's circumference divided by .625 equals number of strips Measure the kerf of your saw blade and you are on your way to getting an accurate number.

It's worth finding the ballpark figure but try not to sweat it too much. I wish I had had my mind more on consistent color/grain when I was at the lumber yard instead of math.