While keeping the tag [boat] for genereal purpose we could consider to add tags as:
[motor-boat] [rowing-boat] [sail-boat].
edit (answer by: Kevin): motorboats rowboats sailboats
As the site is young and so not many questions are tagged [boats], I suspect it will grow in time. There is a significant different in handling, maintenance, rules and interests.
For the canou there is already a tag.