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Stopping shaft from turning after loss of an engine

Discussion in 'Technical Discussion' started by CSkipR, Aug 7, 2011.

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  1. CSkipR, Aug 7, 2011
    #1
    CSkipR

    CSkipR Member

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    If you lose an engine at sea and have to return on one engine what is the best way to keep the non-working shaft/prop from turning so the dripless bearing doesn't overheat? i.e. 2.5" shaft
  2. Fishtigua, Aug 7, 2011
    #2
    Fishtigua

    Fishtigua Senior Member

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  3. K1W1, Aug 7, 2011
    #3
    K1W1

    K1W1 Senior Member

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    Hi,

    A Shaft Brake would be the best way but for something that you have to jury rig there are a few options.

    A Vice Grip Chain Wrench can be used if it can be either pushed against something solid of tied to something solid to stop the shaft turning, a bar or pipe slipped through the coupling which can be stopped from turning by something solid can also do the job. Tie a rope around the coupling and attach it to something solid.

    All the above should be attempted only when the shaft is stationary as the risk of even a slow turning shaft to pull body parts off is quite high.
  4. CSkipR, Aug 7, 2011
    #4
    CSkipR

    CSkipR Member

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  5. K1W1, Aug 7, 2011
    #5
    K1W1

    K1W1 Senior Member

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    Hi,

    You would be trying to clamp something round with the use of two flat smooth surfaces so I would not rate the chances of success very high first time.
  6. Loren Schweizer, Aug 7, 2011
    #6
    Loren Schweizer

    Loren Schweizer YF Associate Writer

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    Hence, the good 'ol-fashioned monkey wrench designed for gripping pipes and shafts.
    Your Granddad has one in his garage.
  7. CSkipR, Aug 7, 2011
    #7
    CSkipR

    CSkipR Member

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    Got one. Thx
  8. Capt J, Aug 7, 2011
    #8
    Capt J

    Capt J Senior Member

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    I just use a rope and wrap it many times around the shaft opposite of the direction it's going to turn, just like wrapping a piling and then tie it off to something solid in the engine room such as the motor mount on the other side of the aisle.

    It's also pretty easy to run a crossover from each engine and a shutoff valve and then you can just open the valve and the water flow from the running engine will cool the shaft on the engine thats not running. All you need are a few 3 way hose barbs, hose clamps, hose, and an inline shutoff valve.
  9. C4ENG, Aug 7, 2011
    #9
    C4ENG

    C4ENG Senior Member

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    What about putting the gear in reverse then shutting down the engine and letting the gear box hold the shaft from turning?
  10. dsharp, Aug 7, 2011
    #10
    dsharp

    dsharp Senior Member

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    Modern gears use oil pressure to "lock up" the clutch plates. If there is no pressure the gear slips. You can also put a box end whench on a coupling bolt. Make sure it doesn't hit any lines or hoses.
  11. Beau, Aug 7, 2011
    #11
    Beau

    Beau Senior Member

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    That old fashioned monkey wrench works very well. Try to wrap the shaft with some tape where it will bite to help prevent nicks, and make certain there is a board or something between the handle and the hull. You also may want to put some plastic ties on the wrench head to keep it place if its bouncey. Another quick fix is to loop a v belt thru itself around the shaft then tie it off tight to a sturdy part of your bilge with a piece of line.

    BTW. It a good idea to be sure which way the shaft is going to rotate before you apply the remedy
  12. Pascal, Aug 7, 2011
    #12
    Pascal

    Pascal Senior Member

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    I've used two lines: one tied around the shaft with a short (2 or 3") loop sticking out, and the other one tied to something strong like an engine/tranny mount, etc... into the loop and back. you can also use a shackle to attach the line to the loop.

    do not underestimate the mount of pressure you'll get even at slow speed!
  13. NYCAP123, Aug 7, 2011
    #13
    NYCAP123

    NYCAP123 Senior Member

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    Really, it's just anything that works, except I'm not sure I like the putting it in reverse idea. If the oil isn't circulating I not sure I'd want the constant pressure although it would probably be alright. One sound bit of advice came from K1W1 and I want to make sure it doesn't get lost in the talk of tools and clamps.
  14. Laurence, Aug 7, 2011
    #14
    Laurence

    Laurence Senior Member

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    Add cooling

    This sure sounds like the best solution.
  15. Pascal, Aug 7, 2011
    #15
    Pascal

    Pascal Senior Member

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    While a cross over will help the stuffing box you may still need to lock the shaft to protect the tranny as some cannot be freewheeled
  16. C4ENG, Aug 7, 2011
    #16
    C4ENG

    C4ENG Senior Member

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    You need the oil psi in order to engage the gear, but once locked in, it will break before slipping. I am not saying this is the best way of stopping the shaft, but is one way of doing it when timing may be critical or what not.
  17. NYCAP123, Aug 7, 2011
    #17
    NYCAP123

    NYCAP123 Senior Member

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    Also, that's something you'd do if you had to keep traveling. Most boats are heading to the mechanic when they lose an engine. It's usually just a matter of getting safe and underway asap. That night the boat stops until it's repaired.
  18. Capt J, Aug 8, 2011
    #18
    Capt J

    Capt J Senior Member

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    ZF's have a shaft driven pump and can be free wheeled. Some TD's and others may or may not depending on the model......
  19. K1W1, Aug 8, 2011
    #19
    K1W1

    K1W1 Senior Member

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    Hi,

    I don't know what sort of gearbox you have found this on but it is not how the majority of the gearboxes I have encountered operate.

    How do you propose to provide the motive force to get the oil pressure to lock the clutch if the engine on that side is inoperative in the first place?
  20. dominomarie, Aug 8, 2011
    #20
    dominomarie

    dominomarie Guest

    We often go on one engine when fishing with our powercat. To avoid shaft overheating, JP has diverted a line from the washdown pump to keep cooling the shaft. Simple.
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