reverberation on pontoon?

Discussion in 'Propulsion' started by Leveboat, Apr 23, 2017.

  1. Leveboat
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    Leveboat Junior Member

    HI boaters! My husband and I just test rode a 2016 Starcraft CX21R with a 90hp motor. The ride was great, but when we got up to top speed (~27mph) there was some reverberation in the middle of the boat. The marina said that's normal for boats without a 3rd toon, as it's the waves of the lake hitting underneath the boards. It was pretty windy that day, but no one else on the water. Is this normal? We really like this boat, but we're used to riding on friends wake board boats where it's a smooth ride.

    Any insight would really be appreciated! Thanks.
     
  2. ondarvr
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    ondarvr Senior Member

    The water and wakes from each hull can do odd things under the deck, so it's entirely possible that what they said is accurate.
     
  3. gonzo
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    gonzo Senior Member

    The hulls are long tubes of thin section without any dampening, so they will vibrate. Also, the deck is a large flat surface that acts like a drum head. It has nothing to do with the amount of pontoons, but with resonant frequency. That is inherent on the design and materials used.
     
  4. TANSL
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    TANSL Senior Member

    I think reverberation is not same thing as vibration and, of course, has nothing to do with the resonance frequency of a material.
    @Leveboat, could you clarify if what is produced in your boat is a reverberation or a vibration?.
     
  5. gonzo
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    gonzo Senior Member

    Reverberation is a decaying vibration. Reverberation is affected by the resonance frequency. That is elementary vibration physics.
     
  6. TANSL
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    TANSL Senior Member

  7. Leveboat
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    Leveboat Junior Member

    @TANSL @gonzo maybe reverberation wasn't the best term for what we were experiencing (that's just what the guy driving the boat kept saying...).... it was more just a vibration in the middle of the boat (not so much near the bow or stern) caused by the waves crashing into the crossbeams and decking.

    I have to assume this is normal, but we're really interested in this boat and don't want to make a bad decision not knowing. My husband mentioned "under-decking" and asked if that could potentially solve the problem? I'm not exactly sure what that is or if it's easy/difficult to do.

    Thanks!
     
  8. PAR
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    PAR Yacht Designer/Builder

    The 'toon guys are generally correct in that 3 'toon setups, make quite a bit ofvnoise and related vibrations underway. Three 'toon setups are a poor solution to this type of boa,t to gain capasity and trim angles. Accept this trait or look at a "deck boat" instead.
     
  9. Leveboat
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    Leveboat Junior Member

    @PAR I'm not terribly worried about it as long as there is nothing to worry about! :) Just making sure this is normal. I'm sure we'll get used to it, and it really only happened when we were riding at top speed.
     
  10. TANSL
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    TANSL Senior Member

    On catamarans it is completely normal for the "wet deck" to suffer from pressure due to the waves, which can be very large. But, as is a known phenomenon, hulls and decks are usually designed to withstand them. If the vibration is annoying, try to place weight, inside the vibrating area, to reduce it.
    Anyway, this boat that you are testing, should not go, for a long time, at high speeds. It is possible that some other area will suffer unexpected effects.
    This is my opinion.
     
  11. Leveboat
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    Leveboat Junior Member

    That makes sense. Thanks @TANSL! I agree, the plan is to be cruising and relaxing on this boat... I just wanted to make sure this wasn't something we should be worried about. Thanks!
     
  12. slow fred
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    slow fred Junior Member

    2 extra beers and you won't notice it. lol
     
  13. rasorinc
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    rasorinc Senior Member

    slow fred had the most accurate answer............
     
  14. ondarvr
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    ondarvr Senior Member


  15. Mr Efficiency
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    Mr Efficiency Senior Member

    Why isn't there a flat panel covering the cross-beams ?
     
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