I think you should mention drums as a possible item. Rapier also needs to be mentioned as a luxury/situational item (it's so strong!).
If you send the boat through your allies, it douses them in rum and gives bonus movement speed (10%)...this inebriation muffles damage by 50%! This is a big deal. It lasts 8 seconds!
Make sure to send the boat through your allies in teamfights!!!
Also, I like to get tidebringer first unless you are going for first blood or need a stun to escape.
Edit: Against some teams...BKB can be a good choice...(like always)
Edit#2: I find it important to note which spell to cast first when you are going for your combo (torrent + boat + tidebringer). I think in many cases boat first is good because torrent will keep them in place more effectively.
On the other hand...it is harder to hit the torrent if you do it this way.
Make sure to get epic kills vs. invisible heroes with Kunkka Torrent has very long range!