Abviously one the most promising mod this year, but like all new mod, modder forgot to allow naval model for most playable nation. ( testing Wermacht, france and himler, no naval production ). By now when this problem occure i use a old trick consisting of training my current navy to upgrade model to product a fresh one but like i said most country haven't starting navy ( maybe because of the lore ). I think you could just put some naval experience by decision or by the tree before the navy tree appaire after some event ( like germany and the and of civil war which unlock the army tree with experience and other stuff ). Anyway it's a great job you have done.