Sure, you have to reflect that this buffs other Durations. But delayed draw is not that much worse than immediate draw (there are folks who would argue that it is better, which I agree only with in the case of terminal draw) and the card also has to work well in Kingdoms with few or no other Durations.
So yeah, without Caravan in the Kingdom this is a $4.5 and with Caravan it is so close in strength to Caravan that $3 makes it underpriced.
I have made a second version of Boatswain where only one Duration card can get swept away now. This should check the power level of the card itself in check, and you'll probably like to use this power onto a more potent card (such as Wharf), should they be in the Supply. Until then, a single Boatswain at
should keep you going until you find better stuff to discard from play.
What does it mean to have an effect? In a game with Tormentor, can I discard a Boatswain at the start of my turn?
I'm sorry, I do not quite understand the Tormentor question. A card that no longer has an effect is a card that is done doing anything, a card you'd discard from play this turn. It shouldn't be ambiguous in theory, otherwise, people wouldn't know which turn to discard their Duration cards as normal.
. Like Patron. I'll edit it.
, unlike Cutpurse and Militia. In fact, it might just make your opponents hit 
