Trim/Tilt for Outboards and Inboard/Outboards (I/Os)

Chris Riley by Chris Riley Updated on July 31, 2019. In nauticalknowhow

Al asks: “Are there any articles addressing Out Drive tilt/trim?”

Many outboards and most inboard/outboards (I/Os) come equipped with power trim which raises or lowers the drive unit. In this case the term “trim” refers to the running position of the engine drive unit.

Although most people know that the trimming movement raises and lowers the bow, many are unaware that it also can effect steering and performance. When you trim your drive unit either “in” or “out” you may feel a pull on the steering wheel either to the right or left.

If the steering pull grows beyond a slight pull, an inadvertent release of the wheel can cause the boat to go into a sharp turn and passengers could be thrown around, or even out of, the boat. Be sure to keep a firm grip on the steering wheel.

The three positions of trim and results are as follows:

trimindown.gif (4845 bytes) Trimming In (Down)

  • Lowers the bow
  • Results in quicker planing, especially with a heavy load
  • Improves ride in choppy water
  • Increases steering torque or pull to the right
trimneutral.gif (3995 bytes) Neutral Trimming

  • Lowers the bow
  • Normally results in greater efficiency. (Note that the propeller shaft, which connects the propeller to the drive shaft, is parallel to the surface of the water.)
trimoutup.gif (3404 bytes) Trimming Out (Up)

  • Lifts the bow
  • Increases top speed
  • Increases clearance in shallow waters
  • Increases steering torque or pull to the left
  • In excess, causes the boat to bounce




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