rowlock

A rowlock , sometimes spur (due to the similarity in shape and size), oarlock (US) or gate (AUS) is a brace that attaches an oar to a boat. When a boat is rowed, the rowlock acts as a fulcrum, and, in doing so, the propulsive force that the rower exerts on the water with the oar is transferred to the boat by the thrust force exerted on the rowlock.