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Thread: Shaft length and motor mounts - Advice needed

  1. #1
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    Default Shaft length and motor mounts - Advice needed

    Hi all, need some advice here.

    I bought this boat a few years ago and when I got it the motor was mounted on some sort of a mounting system, for reasons that were never really explained to me. I am thinking about upgrading the motor this summer.

    The current motor has a 20" shaft, which I understand is a long shaft. It looks to me like a standard shaft length of 15" would fit the transom if the motor mount was removed (although the motor would sit lower in relation to the driver seat).

    What would you do here? A 15" or 20" shaft motor? Can anyone think of any real reason why this motor mount is even installed currently? It literally does nothing other then raise the motor off the transom a few inches.

    Ive attempted to attach pics. Let me know if they have worked. This site is being wonky for pics lately with me.

    Thanks for your advice.






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  3. #2
    Apprentice

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    The big plate above the prop is the cavitation plate that should be level with the bottom of the boat.
    Looks ok the way it is. But can’t tell for sure from pics.

  4. #3
    Apprentice

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    I’d fill the transom in To 20” as it keeps water from splashing in.

  5. #4
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    My boat has the same set up, the mount is a jack plate to be able to adjust the engine height. My boat would likely fit a short shaft but I think it would cavitate in rougher water, also it came with a long shaft from the dealer that was mounted too low, I added the jack plate to optimize the mounting height for better planing and less drag.

    For the sake of saving any trouble being too short, I'd stick with what you've got. I see some marks on the transom where there was an engine mounted before so who knows?

  6. #5
    Needs a new keyboard

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    Long shaft, short transom, I would do what Glen suggested. You can remove the rear corners, take off the the aluminum cap all the way across. The the wood will slide up, use it as a template and make a new one from either marine ply. You should be able to find other aluminum cap material at any metal shop, rough guessing either 7/8ths or 1 inch. That will make the whole transom less flexible.

  7. #6
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    If the motor with the long shaft came with the boat as new and without the jack plate the boat would never have gotten up on plane, too much drag and the prop would have been too far down into the water. Adding the jack plate got the motor high enough eliminating drag and getting the boat up on plane.

    If the boat and motor are preforming well, why change the set up. If you're getting yourself a new motor stick with the jack plate and 20 " long shaft making it an easy install...
    SkyBlue Big Game Blueticks

  8. #7
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    I would consider a power tilt and trim jack plate. Most outboards between 15 and 40 hp are not equipped to be adjustable in those functions. If adjustable you can tune your setup to suit conditions on the fly. A good example would be having your engine tucked under for a quick "hole shot" then trimming up to improve speed and fuel economy. The only down side to these units is added cost.

  9. #8
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    Thanks for the advice all. I am indeed considering a larger motor with power trim.

  10. #9
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    Just in the process of setting this boat up for fly fishing. Its a 16' X 60" c/w pocket tunnel. The motor has power trim, I added the power jack plate so I can raise the motor up and down thru a 6" range. I can run the prop right up in the pocket for shallow water.



    IMG_20200516_084650.jpgIMG_20200516_084715.jpgIMG_20200516_084751.jpg

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