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G23 Sudden Intense Shudder & Noise - Rudder Vibration?

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  • G23 Sudden Intense Shudder & Noise - Rudder Vibration?

    Having a great day on the lake today, when something let loose while a person was wakeboarding. The whole boat started shuddering and making a crazy noise. Pulling the boat out the prop and shaft seemed fine and no visible sign of anything wrong elsewhere. The only thing we could find was that the rudder maybe had a little play in it when putting side to side pressure on it - but it didn't seem overly loose.

    We checked the rudder internals out and the massive brass nut on the rudder shaft was finger loose, with the locknut also spinning freely. Hopefully tightening this back up will take a little play out of the rudder and solve the issue. The rudder doesn't have a ton of play in it, but I wouldn't think it would take much to get a good shudder - a lot of pressure on that bad boy.

    Anyone ever experience this? What is the process for tightening that rudder nut up (how tight, etc.)?

    Again, it doesn't have a lot of play in it, so hopefully this is not a red herring.
    Last edited by blueroom; 06-14-2019, 12:51 AM.

  • #2
    Checking for excessive rudder play on an inboard:


    • #3
      You may have just picked up a piece of debris on the prop. I once hit a plastic bucket it stuck on the prop and vibrated like crazy. Reverse will spin it off most of the time.


      • #4
        I changed out my prop on my g23 a couple of weeks ago and while I was under the boat examine the the four bolts holding the rudder plate..all four were extremely loose , never experienced any looseness (while driving) but had to be getting excess water in boat.. notice for long time bilge pump dumping occasionally while out, but never gave much thought since it was doing its job... each 9/16 bolt took about a turn and half, just FYI next time you have your bottom exposed.....
        2013 G23 super air
        2010 230 super air
        2009 220 super air
        2008 210 super air
        2005 210 super air
        2003 calabria pro air


        • #5
          Originally posted by Nautiquehunter View Post
          You may have just picked up a piece of debris on the prop. I once hit a plastic bucket it stuck on the prop and vibrated like crazy. Reverse will spin it off most of the time.
          I had this happen once with a small piece of wood, but it doesn't seem to be the case with blueroom since he's inspected his prop.
          2007 Malibu Wakesetter 23 LSV, 1995 Cobalt 200


          • #6
            Blue- 10$ says you hit something with your prop and you now have a bent prop.

            bent fins may not be easily visible.

            Do a prop swap.
            2019 G23 450
            2014 G23 550
            2013 G23 450
            2011 Malibu Wakesetter 247
            2007 Yamaha AR210


            • #7
              I have hit a patch of milfoil that stopped me in my tracks; I thought the boat was surely destroyed it was so violent, but, once cleared, there was no damage. I have also had prop damaged by an almost imperceptible strike on a stick that bent it that was almost invisible to the naked eye that caused bad vibration. Sometimes it is tough to tell, but you do need to make sure the prop is balanced if there is a doubt.


              • #8
                As mentioned, the rudder shaft nuts were loose - almost free spinning. We tightened them up and now there is zero shake in the rudder. Hoping that is it. It could be a prop, but ours is almost brand new and shiny - there is not as much as a scuff on it. I would think we would see some kind of indication. We'll take a spare with us tomorrow when we go to the lake just in case.

                The tightening process was pretty scientific - one person in the hatch working on the rudder and one person testing the rudder shake and steering feel. We just got it to where the rudder seemed tight and the steering loose.

                I played with other G23 rudders yesterday. The new boats were tight like ours is now. Boats that were a year or so old had similar shake in the rudder as ours did before tightening the nuts, maybe slightly less shake.

                Anyone know if checking the rudder nuts is on the maintenance schedule? It's crazy how huge they are, a really engineered part, and that they can loosen up like that on their own. But..... we have had even crazier "loosening" issues on our boat. : )
                Last edited by blueroom; 06-15-2019, 10:08 AM.


                • #9
                  Funny how props are. Wifey bent my prop last night and there was zero vibration afterwards. Still getting it fixed but I couldnít believe how smooth it still was. Then sometimes you canít tell and it vibrates like crazy...
                  2006 SV 211
                  97 Sport Nautique (Sold)
                  89 PS 190 (Sold)
                  05 Fourwinns Horizon 180 (Sold)
                  89 Fourwinns 170 Freedom (Sold)
                  75 MFG (Sold)


                  • #10
                    It was 100% a loose rudder. Steering feels even better than before - nice and precise. I think the nuts on the rudder loosen over time and should probably be checked and tightened if needed. If you grab the rudder and it rocks, you can tighten it up. A slight click back and forth in the rudder cable is normal, but it shouldn't rock front/back or side/side.


                    • #11
                      The fact that it came on instantly almost guarantees you wrapped something on the prop. Usually as mentioned falls off when you select reverse. Vibration may have helped loosen bolts. Wrapping even a plastic bag can be violent.


                      • #12
                        Nope. We checked the prop while still in the water and troubleshooted for half an hour.

                        The Nautique dealership did the repair. The main nut, and locknut, holding the rudder shaft should no be free spinning.