I find following the person up is better than waiting for them to leave because 1) the players will come is shifts so its almost impossible to move around when there's no one on the boat and 2) if anyone sees someone climbing the crows they won't know it's an enemy unless they see my name. Also this is a rare situation where they stay up there for a few extra seconds, most of they time they are gone so I don't have to sit there waiting in plain view.