Torque steering -- when your motor tries to pull the stern of the boat in the direction in which the propeller turns when you're backing the boat -- is one of the small problems you deal with on a boat with a single propeller. When a boat moves, only one side of the propeller digs into the water as it turns, pulling the stern of the boat in the same direction. The solution lies in a device called a trim tab.
Items you will need
Socket
Observe the direction in which the stern of the boat moves when you back up. If the stern moves to port, that means you need to exert a force on the starboard side of the motor.
Locate the trim tab. If your boat is powered by an outboard motor, the trim tab will be attached to the bottom of the horizontal cavitation plate that looms above the propeller. The trim tab resembles a small boat rudder. In the center of its base is a nut.
Loosen the nut with a socket. If the stern of the boat moves to port, adjust the trim tab to starboard. If the boat moves to starboard, adjust the trim tab to port. Tighten the nut securely.
Watch how your boat behaves when you back it; readjust the trim tab to fine-tune its effect on your boat, if necessary.
Adjust hydraulically-controlled trim tabs on boats with inboard and inboard/outboard motors by lowering the trim tab on the side of the boat opposite the direction in which the stern pulls when backing; if it pulls to port, lower the starboard trim tab; if to starboard, lower the port tab. Raise the trim tabs when moving forward.