Black Tide Raider

You can't have a second copy on board.

It can be dispatched, and use Exhaust abilities, in the turn it came on board during a watch.

Not when you deploy it: it happens once it has resolved and is on board, after your opponent's chance to react. Put on board without being deployed, as by Resurface, it happens too. In the sortie phase it goes into the crossfire (301.10). Choose one of your opponent's crew on board when it happens; with only one, it is chosen, and with none, nothing happens. An exhausted crew can't be dispatched, so it doesn't defend or go to an expedition, and can't pay an Exhaust cost; it becomes ready in its owner's stoke phase (801.13).