Barend Migchelson shows how to do it for dories with just the Pythagorean
formula. He's in Dorval (Montreal), Canada and has a website
I worked it out for skiffs using analytical geometry and put it in a
program for flat bottom skiffs at www.ncf.ca/~ag384/Boats.com.
You should be able to do quite well with a protractor and a wire frame
diagram produced by a (free) hull design program like the one at
www.carlsondesign.com which is for plywood boats and will draw and list the
points to plot for cutting out the plywood panels as well.