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'05 X-9 Top Speed Issue

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  • '05 X-9 Top Speed Issue

    Neighbor on the lake keeps his son in law's '05 X-9 with the 350hp MCX. Boat does not get used very often, but was used pretty heavily all weekend 2 weeks ago. Some point in the weekend, the boat started topping out at 35mph instead of the ~45 it used to top out at.

    Engine runs smooth through the RPM range, and a visual inspection of the prop/driveshaft yielded nothing out of the ordinary. At ~25 mph you can feel a slight abnormal vibration.


    Most of the neighbors suspect a slightly bent prop. I'm not aware of any other possibility, other than some sort of unlikely engine problem that has resulted in reduced power without affecting how the engine revs in neutral.

    Any ideas? Suggestions on where to get the prop checked?
    Bailey
    '02 X-9
    Lake Blue Ridge

  • #2
    Bent prop, bent shaft, maybe bent strut or bad alignment. Sounds like something going on in the drive train.

    Although quality of repair can be variable among prop repair places, they should definitely be able to check it for damage, assuming they have the correct pitch blocks. Alternatively, sending it back to OJ for evaluation and/or repair is always an option.
    '04 MariStar 230VRS/MCX

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    • #3
      What is the max RPM at 35? It would be something more than a slightly damaged prop to lose 10 MPH.
      Eric Johnson
      Johnson Propeller Co., Inc
      [email protected]
      ojprops.com
      800-359-9730

      sigpic

      Comment


      • #4
        Really sounds like a bent prop, or something in the drivetrain.

        Sounds similar to the same thing that happened on my old Mari 210. The prop "ding" was not even a ding, but a bend that was not noticeable due to the cupping of the blade making it hard to find.

        It was there though, and no matter how hard I rammed the throttle, it would not go.

        Good luck with it.
        16' X-10
        04' X-9.
        91' Maristar 210.
        sigpic

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        • #5
          any chance the perfect pass was set at 35 for a skier and not turned off?

          Comment


          • #6
            I would double check speedo calibration. Those two buttons are too close together, and I switch my calibration off at least once a weekend. Double check with a portable GPS, if it truley has lost that much speed, I would guess prop/shaft too

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            • #7
              04 x9

              My boat's top end is around 37mph at 4500rpm. Indmar 310HP with stock prop. We bought the boat used last year. Is this speed and rpm sound normal with stock prop? Any suggestions?

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              • #8
                Originally posted by shamco View Post
                My boat's top end is around 37mph at 4500rpm. Indmar 310HP with stock prop. We bought the boat used last year. Is this speed and rpm sound normal with stock prop? Any suggestions?
                37 @ 4500 does not sound very good, a bit slow for the RPM.
                Eric Johnson
                Johnson Propeller Co., Inc
                [email protected]
                ojprops.com
                800-359-9730

                sigpic

                Comment


                • #9
                  The prop and shaft rotate freely by hand with transmission in neutral, so I would assume that rules out an extreme bent strut or really bad alignment.

                  Who is OJ?

                  I didn't look at the tach at max speed. I'm no longer at the lake, but I'll ask the owner to take it for a run and record max rpm.

                  Perfect Pass was turned off.


                  The speedo calibration is a great suggestion. I wish I had thought of that this weekend. I called the owner and asked him to take a GPS and get a real speed so we can know for sure how much of a problem there really is.
                  Bailey
                  '02 X-9
                  Lake Blue Ridge

                  Comment


                  • #10
                    OJ is Johnson Propeller/OJ PROPS. We make propellers/underwatergear for tow boats.
                    Eric Johnson
                    Johnson Propeller Co., Inc
                    [email protected]
                    ojprops.com
                    800-359-9730

                    sigpic

                    Comment


                    • #11
                      Originally posted by CruisinGA View Post

                      Who is OJ?
                      OJ Props is the OEM supplier to MasterCraft for propellers.

                      Eric Johnson is the Big Boss there, he's posted twice in this thread.
                      '04 MariStar 230VRS/MCX

                      Comment


                      • #12
                        Assuming this is the original prop, chances are it's an OJ Prop, right? Any way to tell for sure?

                        If it is, does OJ offer an inspection/ repair service?

                        Thanks for the help.

                        Bailey
                        Bailey
                        '02 X-9
                        Lake Blue Ridge

                        Comment


                        • #13
                          I'd be happy to take a look at the prop. Give me a call with any questions Eric - 800-359-9730 ojprops.com
                          Eric Johnson
                          Johnson Propeller Co., Inc
                          [email protected]
                          ojprops.com
                          800-359-9730

                          sigpic

                          Comment


                          • #14
                            What engine do you have? Are your props close enough in size to swap them to see if there is any difference? They may not compare but hey, it's a free test...

                            Comment


                            • #15
                              Eric- Right after I posted I found the OJ Prop website and the page concerning prop repair.

                              If he decides he needs to have his prop looked at, I'll give him your number and point him to ya'lls website.


                              Hollywood- I have the 330hp engine. I already offered my prop, but he won't let me take it off to try. One of our neighbors has a spare prop for his Malibu that looks very similar, he may give that a shot.
                              Bailey
                              '02 X-9
                              Lake Blue Ridge

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