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Is my OB too low in the water?

thomasgf Member Posts: 8
edited May 2020 in General Discussions
I bought a used 2005 GS201 fundeck with a 140 Johnson OB. I notice at medium to high speeds water rooster tails up from either side of the OB with trim down. The OB has 5 mounting holes and is in the middle one. Is this normal or is my OB too low? Should I move the OB up? Like try a 1 hole difference to see if that helps. 


  • cjjjdeck
    cjjjdeck Member, Moderator Posts: 1,872 ✭✭✭✭
    I know you are specifically asking about the rooster tail, but you may first want to see if your cavitation plate on the motor is level with the water at cruising speed with minimal trim.  That will give you an idea if the engine is sitting too high or low.

    Here's what you would experience when the motor is too low:
    You can often tell that an outboard is too low if you are experiencing sluggish speeds, poor handling, excessive spray, porpoising, or even water pushing up into the cowling. 

    Here's what you would experience when the motor is too high:
    The symptoms of a motor too high is cavitation on the hole shot and on turns.  The propeller tends to ventilate, losing its bite on the water and blowing out while turning.

    2012 SD237 I/O Mercruiser 5.0L MPI ECT/ Bravo 3
    2012 Load Rite Elite Tandem axle trailer

  • jflang
    jflang Member Posts: 3
    I experienced the same problem with my 1999 Hurricane fundeck 232 with 200HP Mercury outboard.  I had to trim the motor up quite a bit to get the rooster tails to go down, and my outboard was set as low as it would go.  I raised the motor 2 holes, and the rooster tails disappeared.  I only gained about 1 mph on the top end, but my hole shot is much improved.  The boat also seems to handle better, and I have not experienced any cavitation.  The boat has a stepped hull, and the cavitation plate was set at the bottom of the actual hull, not the back of the "step" or back of the boat.  Raising the motor was a significant improvement.