Rather begs the question about how you copyright a scale model of a full-size boat. Do you make it as exact as you can, and therefore risk someone else being as accurate, pernickety and maybe litiginous; or do you introduce a deliberate error which distinguishes it as your own work but makes it "un-scale"?
Fortunately very few folk make a living out of model boat kits - well, too few to bother a sizeable US company which is probably owned and run by lawyers and/or cost-accountants anyway.
Trust me - I wrote the book!
DaveM