Heaps of fun building boats.
I think I'd be buying some metric measuring equipment, rules, tapes etc. and work to the drawing dimensions to remove the problems associated with incorrect conversion calcs. Metric is much easier to work with than the very painful imperial system. It'd be a good exercise.

You don't need a 'sub-deck' to stiffen the bows on a 14. If you need anything (debatable) lay up some carbon on the inside side walls of the hulls from the front chainplates to side chainplates. Less weight and and plenty strong enough if you use the right weight cloth and epoxy resin. How far from the bows is the main beam?

Good luck with the project.
Bern