The oars could move with his connection to the boat, like SS said. Or when he rows the two oars, maybe the Boat reacts and just moves the rest of the oars.
Or my thought building off the previous a bit. Maybe Stranger rows two oars, while then he uses his mind to tell the boat to move the rest of the oars at the same time he is moving his own, making the boat much faster. Thus, a more effective way of travel for him from place to place.
