I'll second the suggestion that you model a cruising yacht.
I did one of those square rigger kits (Artesarnia Latina
Scottish Maid - looks nice, took four years) and then I used the same technique to build a model of a cruising yacht of balsa (three months).
The cruising yacht is 1:20 scale. I was "inspired" by a noted designer
and used a photocopier to get things almost right.