Chine walk speedboat

Discussion in 'Stability' started by Starholk, Aug 27, 2019.

  1. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    This is rather disappointing. That is a pretty low number.

    I would take some film of one of the chines and post it or make it available to pros. You would need to mount it somehow.

    A few of those go fast guys might see the boat and know the issue. Not me.
     
  2. fallguy
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    fallguy Senior Member

    It is a tricky view, but you are right.
     
  3. Starholk
    Joined: Aug 2019
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    Starholk Junior Member

    No. They are rotating different ways.
    I got a tip from a guy with good knowledge in racing. He said i need cleavers. The 2 props are lifting the boat too much. And the boat is made for rough sea. So now i need to find some cleavers to see if its better.
     
  4. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    have you done much experimenting with engine trim/jacking height, to see what effect on the issue ?
     
  5. Starholk
    Joined: Aug 2019
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    Starholk Junior Member

    Yes have tried everything. Its not so much difference what setup i try.
    I try to find some used cleavers to try.
     
  6. Mr Efficiency
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    Mr Efficiency Senior Member

    I guess in the greater scheme of things, not a hugely expensive experiment, with the different props, hope it does the job, but I doubt it will make much difference.
     
  7. Christian Lucas
    Joined: Dec 2018
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    Location: Munich

    Christian Lucas Junior Member

    Hi,
    you have now the propellers spin outside in the water. Fabio Buzzi says that is the better and more stable way. But for a test you can change the motors and let spin them inside in the water. With modelboats we have experiment that in many set up with different result, some hull like inside, some hull like outside spin. For a speed record monohull we placed the propellers far outside the hull to get most triangle stabilisation. Pictures from the modelmonohull from my friend Ralf Moser, that show far out propeller position. This boat run with no chinewalk. top speed about 100 mph.

    Happy Amps Christian
     

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  8. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    I want to express zero knowledge about high speed boats.

    But. I have a question.

    Have you checked to see if those trim tabs are in good water throughout your ramp up to 70?

    I am guessing they are in good water until 70 at which point the water coming off he strake becomes too turbulent and the trim tab actually causes the instability, or at 70, the trim tab point is like a knife edge regardless of the strake turbulence because you are not in enough water with the tab.
     
  9. JSL
    Joined: Nov 2012
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    JSL Senior Member

    Interesting problem.
    May be a tall stretch but....
    If there is a 'cabin top' that is enclosed (I can't see on the photos) this might be behaving like an aero-foil & creating lift at higher speeds: could be messing with the dynamics.
    Years ago I was on a 21' open boat with a fabric bimini top. At 45+ kn. it started wobbling around. One fellow noticed the top was almost 'inflated' like a parasail. He threw some ropes over & tightened to 'collapse' the fabric. Problem solved.
     

  10. powerabout
    Joined: Nov 2007
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    powerabout Senior Member

    many race boats chine walk its just a driver skill to steer them out of it as it usually happens at less then full speed especially when you dont have a plank.
    Have you driven race boats before and have you driven single engine vee bottom ones?
    If not I suggest you go out with someone that has for a bit of training
    I assume the engines have solid mounts?
    Are they sportmaster lowers painted black?
    How much do you need to turn the wheel to get a reaction?
     
    Last edited: Dec 15, 2019 at 3:40 AM
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