Finds an exit of the actor's room by way of the variant search at 9E6E and, if there is one, removes its three bytes, presumably meaning to seal up a way through once something (perhaps the boat) is no longer there to use. But nothing in the game calls it: it is not wired into any object's handler list, any room-entry handler, or any timer, and no other routine calls or jumps to it. Like A0DE, it appears to be leftover or abandoned code.