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Motor for Capri 18

Discussion in 'Smaller Boats' started by john6206, Jan 3, 2019. Add this thread to a FAQ

  1. john6206


    Joined Feb 19, 2008
    77 posts, 7 likes
    Catalina Capri 18
    US ann arbor
    Hi All,

    Used boat came with Mercury 6hp. Pushes the boat really well, but under certain circumstances it seems too short.

    * pulling into a dock, my wife goes to the bow, motor starts sucking air.
    * in waves of any size I need to lower the mount until the mount is dragging in the water

    I assume I need a “long shaft” motor. I’m not sure how to measure to know what I currently have.

    Any motor recommendations? I don’t really want to spend unnecessary money, the motor I have is in great shape.


  2. justsomeguy


    Joined Feb 20, 2011
    6,808 posts, 1,111 likes
    Island Packet 35
    US Tucson, AZ/San Carlos, MX
    Or an "extra long".
    Measure from the top of the cavitation plate up to the inside top of the motor's clamping area, the part that sits directly on top of the transom.

  3. RussC


    Joined Sep 11, 2015
    1,179 posts, 513 likes
    Macgregor 25
    US Oregon lakes
    Shaft length is measured from the top of the mounting bracket saddle, where it fits over the transom, to the cavitation plate just above the prop. 15 - 19" is std shaft - 20 - 24 = long shaft, 25-29 = X long shaft. sounds like you have a std shaft motor.
    It's a lot easier to find a good used std shaft, so I've purchased one of those in like new condition and added the 5" extension kit to make it a long shaft. that's how the factory did it, so these are factory OEM parts. e-bay often has both new-old-stock as well as used "kits" to do this. it's an easy conversion if you have basic mechanical abilities. I paid $150.oo for a new-in-box kit for my like new 3hp Johnson.

    Also easy to tell at a glance (at least on Johnson, I never noticed Merc.) because when an extension is in place you'll then have two cavitation plates, as shown below. one original and one on the new extension ;) .


    Last edited: Jan 3, 2019
  4. john6206


    Joined Feb 19, 2008
    77 posts, 7 likes
    Catalina Capri 18
    US ann arbor
    Based on that measurement I have a 17.5” shaft.

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