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Choice of prop size

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  • Choice of prop size

    I have a pre-1996 22' centre console Mako.

    Powered by 2 x 85hp Yamaha outboards.

    40 gallon inboard tank.

    The present props are 13 x 17".

    The Mako gets up on the plane very quickly, with 5 persons aboard. It planes at circa 2,250 revs.

    On this island in the Caribbean we have a 59% duty on the Cost Insurance and Freight (CIF) price and there are no 'prop' shops where I could try used 19" props.

    So it would be an expensive exercise to buy the 13x19 props and find out that they are not appropriate.

    Top speed will presumably be a bit quicker , which is the object of the exercise.

    Acknowledge that it may take a sec or two longer to get up on the plane.

    1. Will planing revs will likely increase?

    2. What happens to the get up on the plane?

    3. Will they cavitate?

    Anyone experience this situation i.e. what will likely happen, if I replace the 13 x 17" props with 13 x 19" ones?

  • #2
    You didn't say what your wide open RPM's are with your current setup or what your top speed is now.

    If you are at recommended max RPM with your 17 props, going up in pitch won't really benefit your will load them and cause other problems.

    Yes, you may gain some speed but at the cost of premature wear on your engines.

    If you feel that your speed is suffering, there may be other issues coming into play...excessive drag (bottom growth?) or engines at the wrong height.
    1992 211 w/175 OptiMax
    Glen Campbell, Pa.


    • #3
      WOT 5500rpm

      Not sure of top speed, i.e. no speedometer.

      Tend to accelerate get on the plane, then reduce throttle until the boat planes comfortably at the lowest possible revs +/- without coming off the plane.

      This becomes my cruising speed.

      Naturally this depends on load and weather conditions.


      • #4
        With a WOT of 5500, that is pretty much where it needs to be, the 19's will load that down.

        "Top speed will presumably be a bit quicker , which is the object of the exercise."

        "Not sure of top speed, i.e. no speedometer."

        Now I'm really in the world are you going to tell if a prop change is satisfying your "object of the exercise"???
        1992 211 w/175 OptiMax
        Glen Campbell, Pa.