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Pulling to the right at high speed

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  • Pulling to the right at high speed

    On our first voyage we noticed that the higher the speed the more the boat pulled to the right.
    we have a 20' predator with 302 Ford with a standard rotation engine with a LH prop.

    Any one have any idea how to fix this

  • #2
    It is normal due to the prop spinning pushing water against the rudder. You have two options. Switch to hydraulic steering Or install a Teleflex no feedback system. The teleflex uses a clutch to eliminate the problem.

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    • #3
      Your rudder just may need “tuning”. Google rudder tuning. It involves lightly grinding the trailing edge of the rudder, a little goes a long way. Many ski boats pull to one side to load the steering so that the boat tracks straight through a ski course. If it tuned neutral the boat can start weaving as you correct from side to side.

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      • #4
        Originally posted by jkraft View Post
        It is normal due to the prop spinning pushing water against the rudder. You have two options. Switch to hydraulic steering Or install a Teleflex no feedback system. The teleflex uses a clutch to eliminate the problem.
        ....................

        '78 20ft Cuddy
        Mercruiser 350 FWC preVortec w/Carb

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        • jkraft
          jkraft commented
          Editing a comment
          Does this mean I am right or wrong? Lol

      • #5
        Originally posted by jkraft View Post
        Does this mean I am right or wrong? Lol
        Easy way of sayin times 2
        '78 20ft Cuddy
        Mercruiser 350 FWC preVortec w/Carb

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        • #6
          In all due respect your both wrong, all a hydraulic or no feed back system does is mask the problem- does not fix the original problem of the water pressure being greater on one side of the rudder over the other making it pull. Much like an airplane wing creates lift. Fix the rudder to a more neutral "lift" and it won't pull. Shamrocks been out of production for what something like 10 years? Inboards have since moved on,some boats are pushing 550 HP, rudders have changed also to compensate. Here is a picture of a rudder used on these newer boats,it has a tab that is manually adjustable. All this does though is make it easier to adjust. In a non tabbed rudder you must grind and you have to be careful not to over do it, a little goes a long way.



          Click image for larger version  Name:	1428.jpg Views:	1 Size:	25.7 KB ID:	21889
          Last edited by gary s; 06-12-2019, 08:57 AM.

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          • #7
            Please correct me if I am wrong. But I thought the way a rudder works is with a pressure difference across each side?
            '78 20ft Cuddy
            Mercruiser 350 FWC preVortec w/Carb

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            • #8
              I think your right but I'm not an engineer or physicist. That said, when your going straight pressure should be equal on each side. When its not that's when it pulls. It is very similar to an airplane rudder- they have an adjustable trim tab so you can adjust it for different speeds. It's a compromise with a boat since you cannot change it underway but adjusting for your cruising speed will help.

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              • #9
                Reminds me of the pull problem experienced on the original Fishineer - the 26’ Cuddy now owned by Jerry. It was back in the early 1990’s when Shamrocks were in production in Cape Coral and I called the factory for advice and was told how much and which rear corner of the rudder to grind off. The original rudder had rear sharp corners and a straight vertical face around 1/2 - 3/4” wide. I had a prop shop chamfer the edge as directed and the rudder neutralized. A good prop shop can probably tune it to neutralize the pull.
                Kingfisher
                1990 22' PREDATOR INDMAR 5.7 310 HP and ZF 45 C
                Fishineer
                1976 20' CENTER CONSOLE Ford 302 and B/W 1:1
                Wilmington, NC

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                • #10
                  WOW! So I don’t have to deal with this pull forever based on what you guys are saying. Would a prop shop know how much to take off right off the bat or would I have to give them the dimension and amount?

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                  • #11
                    I would google it to see what it takes and do it myself,there are several forums with info on it. If you have the ability to pull the boat out of the water yourself go slow and only remove a little at a time.relaunch and try it.

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                    • #12
                      After seeing all the different answers I looked a bit more carefully at the rudder and I noticed a slight angle from top to bottom. Dose any one k ow of a good place to either straighten it or get a new one??

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                      • #13
                        You may want to purchase a trailer hitch that lowers the trailer tongue and raises the bottom of your rudder to avoid driveway dips. I would prefer to repair the hitch or curb instead of the rudder.
                        Kingfisher
                        1990 22' PREDATOR INDMAR 5.7 310 HP and ZF 45 C
                        Fishineer
                        1976 20' CENTER CONSOLE Ford 302 and B/W 1:1
                        Wilmington, NC

                        Comment


                        • #14
                          Working off memory, which is dangerous, but pretty sure I have a similar slight angle from top to bottom. (Possibly to enable pulling the shaft without pulling the rudder?) I'm the original owner and have never hit bottom in a way that would challenge the rudder. Additionally, have had the rudder out and it was straight. Guessing this is not a problem.
                          C Rhodes
                          26' Mackinaw - 1990
                          351 Indmar (1990-2006: Great Engine)
                          351 PCM (2006 - Current)
                          Southport, NC

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                          • #15
                            Rudder is mounted off center on purpose. Never question George.
                            1988 26' cuddy
                            1975 20' open
                            31 Grand Slam
                            16' Sandpiper
                            14' Certified Fiberglass

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