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  1. #1
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    Prop help please

    I have a 21 ft cobia center console that I have just redone the floor and transom and I'm just getting it on the water , with that said I have a 1990 Johnson 125 25" shaft and when on plane if I give it all the throttle , it will hit 6700 - 6800 rpm quickly .

    I feel this is too much and the prop is a 13 3/8 X 17. Is this close to the right prop ? There is evidence of the rubber hub slipping some but I don't want to pay to have it re worked just to figure out it's the wrong one anyways .

  2. #2
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    Lake Coochiching, Ontario
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    How fast does the boat go? Is 6700 a transient rpm while planing or the rpm at top speed?

  3. #3
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    According to gps and fish finder around 34-35 mph if I remember correctly .

    6700 is all the rpm at top speed . The boat itself comes up on plane easy and quick , just worried about the excessive rpm .

  4. #4
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    I live in Prineville Oregon which is in the central part of the state
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    If the hub is slipping it is a real problem. From what you have posted I would really think about going to a 19" pitch prop. That should lower your RPMs by about 200 RPM. A four blade prop will also give you better control in rough water and less propeller slip.

    Best wishes, Carter Powell

  5. #5
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    you can check your hub, put a 2x4 in so the prop wont turn, engine at idle, shift in to foward. engine should stall immediately. have someone look at a safe distance. worked for me.

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