To expand on the different vessel types I always thought a raft would be quite natural. These rafts could be pre-built or hand crafted.
If an axe becomes an item it could be used to chop palms to make the raft and the palm leaves as the sails. Barrels could be used also. Would work well as an X button interaction
It could also be worked into quests and perhaps as a different way to respawn, as a 'fine' for a lost ship (as there is no loss atm)
or if there would be a way of capturing pirates where you would then be dumped on a remote isle and have to build your raft to escape.
Also as a tribute to 70 years ago of Thor Heyerdahl exploring the Pacific on his kon-tiki raft.