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Rudder advice

moskimoski Posts: 119 Baller
My boat was used in competition. So rudder is set up for ski course. I’m on big lake so mainly free skiing and sometimes I get to ski course in a cove.

Currently If I let go of steering wheel boat turns hard to right.

Which side of rudder would I need to shave a little so either does not turn as hard to right or maybe I try to have neutral/straight??

Thank you

Comments

  • AndreAndre Posts: 1,578 Mega Baller
    Opposite side...What boat? Adjustable rudder?
    The_MS
  • moskimoski Posts: 119 Baller
    2015 TXI. It has the small rudder tab can take Allen wrench too but does not do much.
    but previous guy who took it to tournaments Dennis at Malibu said they ground/shaved rudder on a bit. I thought about reaching out to him but thought to start here first.

    What to use to shave, grind with?

    Thank you for advice in advance
  • BraceMakerBraceMaker Posts: 4,620 Mega Baller
    Look at the prop from behind you'll see the rudder isn't centered. This will always turn the boat to the right or left. A Malibu should be LH prop so rudder is to the left and it will want to turn right. Look at the rudder first most are ground to increase this effect and an opposite grind is appropriate.
  • Dacon62Dacon62 Posts: 816 Crazy Baller
    edited March 4


    This is a Prostar not a Malibu but both are left hand props. The factory grind (shown here before filing) created more torque to the right than I wanted.
    I hand filed the starboard side (arrows point to) in increments till I achieved the amount of rudder torque desired.
    Filed a bit, drove it, filed some more, drove it. Until I ended up with the amount of pull to the right desired.
    You want to maintain some pull to the right as it takes any play/slack out of the steering. Driving a boat through the course with neutral steering will make it more difficult to maintain a straight path.
    You want to have enough pull to the right so that the wheel will move right quickly enough when you relieve pressure from it to maintain your straight line but not so much that it’s a beast to hold on to.
    Good luck.
  • ProStah_SkiahProStah_Skiah Posts: 19 Baller


    The previous owner of my ProStar did not like the right hand torque steer either. This picture is looking down on the trailing edge of the rudder. For reference, the factory grind is on the starboard (right in this picture) trailing edge. They had the port trailing edge ground as shown. The profile, length and angle of the aftermarket grind basically mirrored that of the factory, but with less material removed.

    This produced neutral steering that would track straight in open water with no steering input required and no right hand torque steer. HOWEVER, it was VERY difficult to drive in the course. With no pre-load on the rudder, the tracking feel was very wishy washy and required constant correction back and forth with large inputs to the steering wheel.

    I did not like the handling at all, and ended up having a local machine shop fill and grind the port trailing edge back to square.

    My recommendation is not to dial out the pre-load with mechanical filing/grinding of the port trailing edge. If you do, definitely do not go all the way to neutral. You want some pre-load on the rudder to maintain tight handling.
    BobFSkoot1123
  • dbutcherdbutcher Posts: 464 Crazy Baller
    @Dacon62 In your picture above, is that rudder bent, or are my eyes deceiving me?
  • 2Valve2Valve Posts: 380 Crazy Baller
    Interesting technical discussion.

    So if my rudder is off-center off the propshaft, to the port side as shown in BraceMaker's photo, AND the boat pulls to the right, would I:

    1. Grind the port side of the rudder?
    2. Would I grind the total height of the blade?
    3. Is there a certain angle that I would want to start with?

    Thanks,
    2Valve
  • Dacon62Dacon62 Posts: 816 Crazy Baller
    @dbutcher eyes are deceiving you. Rudder not bent. Notice the rudder and strut are not lined up perfectly in the picture so that makes it look off a bit.
  • moskimoski Posts: 119 Baller
    Damn great info. @Dacon62 @ProStah_Skiah @BraceMaker

    I’m doubting if I even should now. Either way I would like to know the answers to @2Valve has great questions.

    1. Grind the port side of the rudder? Ok I understand that one, grind the left side of rudder.

    2. Would I grind the total height of the blade?
    3. Is there a certain angle that I would want to start with??


    Thank you
  • Dacon62Dacon62 Posts: 816 Crazy Baller
    edited March 4
    I have a Prostar so a different rudder shape than yours.



    Article and pics below about a Malibu rudder that a guy did. He took off a fair bit. The key is to do a bit at a time and test. The angle @ProStah_Skiah shows looks about right.

    https://www.wakegarage.com/projects-archive/miscellaneous-projects/rudder-tune-r108/
  • ProStah_SkiahProStah_Skiah Posts: 19 Baller
    @2Valve @moski

    1. Grind the port side of the rudder?
    Assuming your boats are either MC or Malibu, then yes, grind the port trailing edge to reduce pull to the right. SN has opposite factory prop rotation, rudder grind and torque steer.

    2. Would I grind the total height of the blade?
    You would mirror the length and angle of the factory grind on the other trailing edge. Like what @Dacon62 shows above.

    3. Is there a certain angle that I would want to start with?
    Approximately 45 degree angle.

    It doesn't take a lot of material removal to make a big difference in handling. Go slow with the material removal and test drive. Its a lot easier to take more material off and test drive again than it is to put material back on :) !

  • swc5150swc5150 Posts: 2,499 ★★★Triple Panda Award Recipient ★★★
    It doesn't take all the much grinding to take the torque out, so baby steps.
    Scott Calderwood
  • BraceMakerBraceMaker Posts: 4,620 Mega Baller
    I use a flap disc on a cordless angle grinder. Easy to use and great finish. I do the top third and blend out before the rudder curves. Just a couple touches at a time. You may need to do quite a lot to get rid of the torque effect as even ungrounded rudders have some
  • moskimoski Posts: 119 Baller
    Appreciate the advice!!! Got me thinking maybe not do it. Or maybe do just a little bit, at least I know how if I shave little bit on it.
    I’ll think on it.

    Thank you
  • DeanoskiDeanoski Posts: 1,005 Crazy Baller
    the best thing to do is never let go of the wheel drive driving.
    RednucleusmoskiRichardDoane503Kento
  • 2Valve2Valve Posts: 380 Crazy Baller
    @ProStah_Skiah

    Thank you very much for the detailed info.

    I do love the way my boat loads the wheel in the slalom course, but would like a bit less right wheel pull when free skiing, so I just want to correct a small amount. Good info and I'll start very slow. :wink:
    2Valve
  • lpskierlpskier Posts: 3,128 ★★★Triple Panda Award Recipient ★★★
    Rudder torque is a feature, not a bug.
    John Wilkins- Si non pro sanguine quem ludus ne. #iskiconnelly
    moskiBobF503Kento
  • thagerthager Posts: 5,189 Mega Baller
    Go where the driver points you dammit!
    Stir vigorously then leave!
    moski503Kento
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