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How to Raise the Transom on an Aluminum Boat

by Will Charpentier

There's no need to weld additions to your aluminum boat's transom to increase its height. One non-invasive way of raising the transom on an aluminum boat is to create a "lift" — a bracket that fits over the transom — to increase the motor's height. The completed bracket forms a channel, and the top of the channel holds the top of the outboard bracket a few inches above the transom of the boat.

1.

Weld the shorter edge of a 1-by-2-foot-by-3/4-inch aluminum plate to the side of a piece of 2-by-2 inch square aluminum tubing, 1 foot long. The aluminum plate must be parallel to and even with the long edge of the aluminum tubing. Use a MIG welding machine. Allow the weld to cool.

2.

Turn the aluminum plate and tube over, so the aluminum plate is flat on the welding table. Weld the short edge of a second piece of 1-by-2-foot-by-3/4-inch aluminum plate to the side 2-inch-square aluminum tubing, so the plates form a "U" shaped channel, 2 feet deep. The aluminum plate must parallel to and even with the long edge of the aluminum tubing. Allow the welds to cool thoroughly.

3.

Slide the aluminum plate/square tube bracket into the mounting bracket of your outboard, with the 2-inch square tube at the top. Mark the location of the mounting brackets holes onto the aluminum plate, using a china marker.

4.

Place a 2-inch thick block of wood between the two aluminum plates. Drill four holes through both plates and the wood block, using a 1-inch bit, at the location marked for the motor mounting holes.

5.

Place the channel of the aluminum bracket over the transom at the motor mount location. Position the motor on the aluminum bracket. Install flat washers on the 1-inch outboard mounting bolts.

6.

Push the 1-inch bolts through the mounting holes on the outboard mounting bracket, the aluminum bracket and the transom. Install lock washers on the mounting bolts. Thread nuts onto the mounting bolts and tighten to 55 foot-pounds.

Items you will need

  • 2-by-2 inch square aluminum tubing, 1 foot long
  • 3/4-inch aluminum plate, 1-by-2 feet
  • MIG welding machine
  • China marker
  • 2-by-12-by-24-inch block of wood
  • Drill
  • 1-inch bit

Warnings

  • Use appropriate safety precautions when using any power tools.
  • Disconnect the negative cable of your battery before performing any maintenance 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. Lift the cable from your battery, move it outside of the battery box and close the lid of the battery box. After the work is complete, reconnect the negative battery cable.
  • Whether you work on your outboard motor on the boat or on a storage stand, remove the propeller nut with a wrench. Slide the thrust hub, propeller and washers from the propeller shaft. Failure to remove a propeller before operating an outboard out of the water during maintenance or long-term storage is an invitation to a propeller-strike injury, which can maim or kill.

References

  • "The Complete Book of Boat Maintenance and Repair"; D. Kendall; 1975

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.