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42 searay broken shaft

Discussion in 'Sea Ray Yacht' started by chesapeake46, Oct 31, 2013.

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  1. PacBlue

    PacBlue Senior Member

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    Lapping is the only way to ensure that the contact between the hub and shaft tapers is reaching the maximum level to 100%.

    If your yard is not doing or offering this, they are cutting corners and taking the easy way out..............
  2. Capt J

    Capt J Senior Member

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    Not to mention it's really easy to do. Just put the prop on with valve grinding compound without the keyway on the shaft, put the nut on most of the way by hand and spin the prop around about 30 revolutions. Remove, clean, install keyway, prop, nuts, cotter pin and you're on your way. The big props are a pain to do because of the sheer weight of them.
  3. K1W1

    K1W1 Senior Member

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  4. chesapeake46

    chesapeake46 Senior Member

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    My pics.
    I think the stained area of the shaft stub indicates that the hub was not properly seated.
    The arrow indicated what was still attached.
    The vast majority was separated.

    K1W1, "super tight" is the correct amount of torque applied, to any fastener, to a value of, " just before it stretches and/or breaks".

    I no longer have the cross reference guide for these values and suggest you use traditional ft/lbs or Nm. :rolleyes:

    Attached Files:

  5. chesapeake46

    chesapeake46 Senior Member

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    proper Lapping procedure

    I passed that link on as well.
    Thank you.
  6. K1W1

    K1W1 Senior Member

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    Hi,

    As the failure seems to have been right at the end of the keyway this location might have been a good contributing factor if the keyway was not well finished in the first place.

    Has your friend owned and operated the vessel for all 18 yrs and never had any incident with hitting something or grounding?
  7. Capt Ralph

    Capt Ralph Senior Member

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    Good pics. Thx for sending them in. Looks like some stains coming in from different directions. Also looks like some lapping had been done at some time, with the last wheel?
    18 years old, it could have hit something 17 1/2 years ago or last year. Could have been a blem or an un-finnished keyway.

    I can imangine a poor fitting key.

    Amazing you did not loose the wheel, bad luck/good luck.

    New shaft questions; How much HP are you putting to that wheel? What strength or safety factor is your shop recommending. How did the cutlass & log look?
  8. chesapeake46

    chesapeake46 Senior Member

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    Well, the plot thickens.......
    He had the same problem on the same shaft about three years ago.
    That time he lost the wheel.
    He has owned the boat at least 10 years maybe 15.
    The key was not snug in the keyway but not sloppy either.
    It was relatively easy to slide into place in the hub and shaft.
    He installs the wheels and all maintenance himself under the guidance of the marina owner.
    This marina owner is pretty well known and has a good if not great reputation.
    I throw that in there because my friend is pretty maintenance conscientious, really very mechanically inclined and detail oriented.
    I don't want to make him out like a chump here. He is a smart guy.


    R Crapps, I said the same thing. For bad luck this was pretty good.
    Made it home from a three hour tour before having the problem.
    ( Luckily he had the problem at his home port and not a deserted isle. )

    I don't know the answer to your other questions but I will ask him.
    I do know he has Cats and V-drives.

    He did have a slow but hard grounding two years ago that bent a shaft but I can't say for sure it was the same shaft.
    He replaced that shaft with new.
    He had to swap the wheels also. He had a diver do both wheels at that time, swapped with his spares.


    Ironically he and I were at the same event this year as when he grounded a couple years ago.


    Again, I thank you all for your input.
    It gives us both stuff to think about.
  9. chesapeake46

    chesapeake46 Senior Member

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    PacBlue and CptJ
    After reading the link and the info here, I agree with you both.
    Seems a no brainer.
  10. K1W1

    K1W1 Senior Member

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    Hi,

    This might explain why the nut was not entirely super tight.

    Ill fit on the taper and a bit of out of balance could easily cause the wheel to wobble back and forth however many times per minute that it rotates at and a stress raiser/weakpoint at the end of the keyway easily caused by a chip in the mill tool that cut it could have started the whole story.

    Was this the same side he lost the wheel off 3 yrs ago or the other side?
  11. chesapeake46

    chesapeake46 Senior Member

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    We are pretty sure it is the same side but he was going to go back through his log book to see for sure.
    Of course the log book is on the boat and we are 40 miles away.

    He hauls the boat for winter here every October. Whether he thought to check the nuts after the diver had replaced the wheels is a good question.
  12. dsharp

    dsharp Senior Member

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    When the wheels come back from being reconditioned the keyway is very slightly rolled in on the bigger bore. I assume it's caused when they set the wheel on a mandrel and pitch block. It just takes a couple of passes with a file to insure that the key slides freely through the wheel. We had a piece of a shaft like that on the sales counter for years. It had broken all the way around and flopped like hell but the two pieces wouldn't come apart. I thought when part of the break is dull and part is shiny then it was cracked for a while, but I'm not a metallurgist.
  13. chesapeake46

    chesapeake46 Senior Member

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    42 SR broken Shaft

    DSharp, When we had the shadt here, I thought it looked like it had been fractured for quite a while as well.
    Just from how the stains appear in the cross section phot.

    I still can't believe he did not feel the thing vibrating.
  14. sunchaserv

    sunchaserv Member

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    Is the shaft the correct diameter and alloy for the boat and engine combination? From the tape it looks like less than 2" and with about 400 Hp per side ----??

    If of marginal diameter or alloy, any poor fit of key or prop may be the straw that broke the camels back.
  15. chesapeake46

    chesapeake46 Senior Member

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    The Shat that was bent two years ago was not on the same side as the one that broke.

    The shaft that broke recently, also broke in 2007.
    He lost the wheel at that time.

    The wheels installed by the diver were used only to get home, then replaced with the repaired wheels.
    The spare wheels are 4 blade, the wheels that were repaired are 3 blade.

    The shaft is 1 3/4. These are factory dimensions. Maybe they are to small, but, that would mean SeaRay had some poor engineering or worse. I doubt that.

    The alloy make up of the shaft is unknown to me.

    I think the whole problem was the wheel and shaft fit.
    Lapping will be top priority on the next one as well as re-fitting the other wheel.
  16. Pascal

    Pascal Senior Member

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    Wouldn't be the first time sea ray comes up with some really poor engineering... How big are the motors and what size boat?

    Usually though that kind of failure is the result of an in water prop installation.
  17. NYCAP123

    NYCAP123 Senior Member

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    To me, when I hear the same shaft broke again 6 years later (and neither due to a strike), I have to wonder about a constant stress like allignment. As for SR build quaity, I've always felt that they're built with about a 10 year lifespan in mind. They expect their customer to trade up within about 3 years or sooner. So getting through warranty is all that matters. Like most things today, they're not built to take whatever comes at them. Instead it's more what's the minimum standard we can get way with. They could use a beefier shaft, but why? That would just take away from profits, and their buyers would never know the difference except in the purchase price. For many of their customers their previous boat was a car.
  18. chesapeake46

    chesapeake46 Senior Member

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    S.R. broken shaft

    His boat is a 42 ft SeaRay, Sun Dancer.
    375 Hp Cats. W/ Vee Drives.
    1-3/4 shafts
  19. Capt J

    Capt J Senior Member

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    I have managed/maintained many older searays and currently manage/maintain 2-50' Searays a 1991 and a 1998 and they both have held up exceptionally well and have no inherent issues and have faired much better than many of the competitors in their class.
  20. olderboater

    olderboater Senior Member

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    I think one can only judge a boat manufacturer or any manufacturer against their targeted use and purpose. On that basis, I think Sea Ray has a solid history. Yes, like any, they've had occasional issues, but they would have more just based on their volume. Their business was built on lake and river usage. Then some of that carried over to coastal cruising. My first two boats owned in my life were both small Sea Rays and I never had problems with either one. While they would be inappropriate for an Atlantic crossing, I'm trying to imagine a 99 meter Feadship on the lake. Other than not being able to go under any bridges, running aground regularly, not being able to turn around in any coves, having nowhere to dock, and no one having the ability to haul it out or service it, it would have looked cool I guess.