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Thread: vibration

  1. #1
    Join Date
    Nov 2008
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    Default vibration

    finally took the new boat out for a spin today and good news is that all appears to be ok.. Took her up to 30knts and she planed ok with 4 adults on aboard. However, getting up on to the plane I felt alot of vibration through the boat with the helm shaking.. Could this be an out of balance prop or something else? It's fine on the plane and at displacement speed but not when under heavy loadThanks

  2. #2
    Join Date
    Jul 2005
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    Sounds more like an engine misfire under heavy load, is it petrol? if so probably an ignition misfire somewhere on the HT side.

  3. #3
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    Default

    not really mate, the engine sounds fine... I was thinking cavitation maybe?

  4. #4
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    Quote Originally Posted by oGaryo View Post
    I was thinking cavitation maybe?
    or slack in the steering cables allowing for some slap under power?

  5. #5
    Join Date
    Dec 2001
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    Red face

    Great to hear your out on the new boat,

    I would assume if you can "Drive through it" ie, the vibration is at the same revs every time then it would be prop or outdrive related, try another prop if you have one, always worth carrying a spare so if you dont have a spare then treat yourself to a new one, then give it another go.
    It could however be the gimble bearing, do you get a rummble sound at the same time as the vibration?

  6. #6
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    Quote Originally Posted by enterprise View Post
    Great to hear your out on the new boat,

    I would assume if you can "Drive through it" ie, the vibration is at the same revs every time then it would be prop or outdrive related, try another prop if you have one, always worth carrying a spare so if you dont have a spare then treat yourself to a new one, then give it another go.
    It could however be the gimble bearing, do you get a rummble sound at the same time as the vibration?
    thanks... definitely able to drive through it and I think I may have a clue to the cause, on the trailer I gave the prop a wiggle side to side and back and forth and there's a bit of movement there.. going to check it out later and hopefully it'll just be a case of not having the prop torqued properly.

  7. #7
    Join Date
    May 2005
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    Default

    if props are not secured properly (castellated nut and pin, or proprietary system) it is not unknown for them to unscrew if astern is used suddenly.


    At that point you start wondering if packed the diving suit. If you are quick enough, you can use the MOB on the plotter to locate where you were when the prop dropped off.
    I think, therefore I am. I am, therefore I sail.

  8. #8
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    Smile

    Hope it's your prop, that would be good news.
    Make sure you have all the required components, its easy to forget the thrust washer for instance which could lead to the vibration.

  9. #9
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    Quote Originally Posted by oGaryo View Post
    Could this be an out of balance prop or something else? It's fine on the plane and at displacement speed but not when under heavy loadThanks
    Simple. Travel at displacement speed , save the environment and
    avoid causing wash problems for raggies!

  10. #10
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    just picked up on your comments BH.. tut tut

    anyways, have just taken the prop off and the nut loosened with surprising ease, no white knuckles or handle extensions needed to get it off.. it was no way near 55 lb ft.. I'm guessing that'll be the problem.. not enough prop pressure to cause vibration at low speed, back pressure at high speed would hold it in place? but at relatively low speed under high load when getting out the hole = reverberation. thrust washer looks fine and fits the prop nicely so am going to clean things up as there's a bit of muck on the inside of the prop and then refit to proper torque settings and see how I get on next time out.. will also check the shaft straightness using the chalk on the end of a stick trick that I've read up on

    thanks again for the advice, appreciated as always

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