Tie one end of a rope to something secure in the middle of the boat, like an oarlock.
From the cnn.com
A single sculling oar with an oarlock on the rear transom can be a compact emergency oar.
From the en.wikipedia.org
In the middle of the ship, as the rowers knew, the distance from hands to oarlock was longest.
From the nytimes.com
Sometimes called an oarlock in the USA.
From the en.wikipedia.org
The oars are the same length, but the distance between hands and oarlock, the lever arm, is longer amidships, because the ship is wider there.
From the nytimes.com
The bracket in which the oar shaft rests is referred to as an oarlock and creates a fulcrum point about which the oar shaft can pivot, resulting in leverage.
From the en.wikipedia.org
More examples
Peg: a holder attached to the gunwale of a boat that holds the oar in place and acts as a fulcrum for rowing
A rowlock (UK) or oarlock (US) 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.
(OARLOCKS) Contain and keep the oar in place.
A device to attach oars to a rowboat, allowing the operator to row rather than paddle the boat.
Square latch to hold the oar and provide a fulcrum for the stroke against the rigger.
A U-shaped swivel which holds the oar in place. It's mounted at the end of the rigger and rotates around a metal pin. A gate closes across the top to keep the oar in.
U-shaped, circular or other shape which holds the oar and secures it to the buoyancy tube permitting movement for rowing.
A pivoting frame that connects the oar to the boat.
Holds the oar and acts as a swivel during the drive and recovery.