How to Stop Torque Steer in a Boat

by Will Charpentier
Note the trim tab, protruding from the plate above the propeller.

Note the trim tab, protruding from the plate above the propeller.

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.

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.

Items you will need

  • Socket

Tip

  • You probably will never get rid of torque steering completely, but if you eliminate most of it using a trim tab, you'll learn to compensate for -- and even use -- the bit that's left.

Warning

  • Disconnect the negative cable of your battery before performing this work on your outboard motor, to prevent electrical shock or accidental starting. Remove the nut from the negative post with a 5/16-inch box-end wrench -- the nut on the negative post of a marine battery is always a 5/16-inch nut. If the wrench doesn't fit, you're trying to remove the 3/8 nut on the positive post. Lift the cable from your battery, move it outside of the battery box and close the lid of the battery box.

References

  • "Evinrude Repair Manual -- 2.5 to 250 HP Models, 2002-2007"; Seloc Marine; 2007

About the Author

Will Charpentier is a writer who specializes in boating and maritime subjects. A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. He is also a certified marine technician and the author of a popular text on writing local history.

Photo Credits

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