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  1. #1

    Default Motor revs fast, prop turns slow

    I have a 1978 200 hp Merc. I was cruising at about 30 mph when the motor started to rev higher, but the boat slowed down. I could get the boat to go about 2-3 mph at about 1,000 rpm, but it wouldn't go any faster at higher rpm's. What is the probable cause of this?

  2. #2
    Chief Petty Officer
    Join Date
    Jun 2008
    Posts
    557

    Default Re: Motor revs fast, prop turns slow

    My thoughts are for you to inspect the bottom end. Start with the prop itself.Make sure its not stripped on the splines, and the hub is ok. If that is ok, go to the gear assembly. Last and most likly least would be the driveshaft.

  3. #3
    Vice Admiral
    Join Date
    Apr 2007
    Location
    Wright City, MO
    Posts
    5,422

    Default Re: Motor revs fast, prop turns slow

    If you have a spare prop, put it on and retest the boat.

    Chances are the rubber hub between the prop and its inner splined collar, is slipping and due for a replacement hub to be pressed in by your local prop shop.

  4. #4

    Default Re: Motor revs fast, prop turns slow

    spun hub

  5. #5

    Default Re: Motor revs fast, prop turns slow

    Thanks a lot. This makes sense and should be easy to fix.

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