Sadly, the ship was already IN the river, and neither of his ships were powered by oars.  However, checking the map showed that the river in question, if it was the one he thought it was, didn't go in far, and it was getting late, so the ship was likely just taking refuge there for the night. He signaled the Truewind to keep going, but once they were out of immediate sight of the river inlet, he brought them into a halt, and signaled them to grapple together for the night. He explained to the officers what the plan was, hit the ship in the inlet as it left the inlet, the Fury would cut them off from going back, and the Truewind would get between them and the ocean. At that point, he rather calmly informed both crews that they would have a larger than average night shift in case the target tried to slip out during the night.