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Vibrations during sea trial

Discussion in 'Technical Discussion' started by Beauregard, Oct 13, 2014.

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  1. Deer Dr

    Deer Dr New Member

    Joined:
    Mar 29, 2012
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    Location:
    Solomons Island , MD
    Have a driveline vibration issue on Watermark--53 foot Huckins Atlantic.
    Starboard side no issue.
    Port side while underway you can visually observe drive line start to jump around increasing as you increase RPMs
    Have hauled the boat to try and solve problem.
    Watermark was repowered by Huckins in 2001.
    Only 800 total hourson Commins C450s which are running smoothly.
    Props were replaced 100 hours ago and visual inspection looks ok.
    The driveline is a Python unit with CV joints on each end.
    First step we pulled the Python driveline and reversed it!
    This actually reduced the vibration but not to an acceptable level.
    What I have been told is you can not get replacement parts for the Python units????
    The VEE drives are Twin Disc units again only 800 hours.with the boat out the water properly blocked nothing seems to be loose or can be moved around by hand!
    Trying to figure out next steps to take.
    Any ideas how to proceed?
  2. Capt J

    Capt J Senior Member

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    Could be U joints, could be even internal in the engine.
  3. Deer Dr

    Deer Dr New Member

    Joined:
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    Location:
    Solomons Island , MD
    Thanks for your reply Capt J.
    The Python drive line coupling does not use u joints per se.
    Each end of the drive line has a CV joint and yes they are suspect and the plan is to remove the drive line and exam the CV joints!
    We have considered the engine could be the source of the problem.

    The 1000 hour service was just completed and oil analysis done!
    Oil came back all normal and there aren't any other obvious signs it's the engine or engine mounts!
    Boat does have Glendening synchronized and they have been checked and appear to be doing there job
  4. Capt J

    Capt J Senior Member

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    I once ran a 58' MY with 8v183's, it was a low hours boat (around 600 hrs) but about 10 years old....when my guy who took it in on trade survey/seatrialed it, the port engine grenaded. The seller paid to have the dealer major that engine which they did. The boat ran very good by all means. BUT, it had a vibration at planing speeds......noticable......props checked perfect, u joints looked perfect, alignment I had checked but nobody could figure it out. About 300 hours later it snapped 2 metal injector lines on that motor which I suspect from the vibration, we replaced those. I suspect it had a slightly bent rod or something else in the rotational mass of the engine.
  5. captholli

    captholli Senior Member

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    We went through this on a large sport fish. There are no new stock Pythons available so we were talked into a rebuild situation and removed the drives and sent them out to a shop in Jacksonville, six months later still no drives, It was an on going mess that our only option for escape was to remove the drive line and install new rubber design resilient mounts and use aluminum billet shim blocks to realign for the off set with the inclusion of jack shafts to replace the Pythons. This vessel was out of the water nearly a year due to being told of various fixes for the Pythons.
  6. Deer Dr

    Deer Dr New Member

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    Sorry to hear about that ugly experience!!
    I have not dismantled my Python drive at this stage BUT think it is next step and since thus far we have not found anyone who has replacement parts I'm curious did you get your Python drives back from the shop you sent them out to for repair---not likely given I don't know the size of your drives but there is the possibility you have some salvage parts?
    Right I'm an optimist
    Thanks for responding--when did you have this misadventure-- last year or so???
  7. Deer Dr

    Deer Dr New Member

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    Forgot to ask---was there a reason you didn't just switch to Aqua drive units which I have been told perform a similar function to the Python units?
  8. captholli

    captholli Senior Member

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    These were one off manufactured Pythons for 2,100HP and never should have been considered for this H.P application. They failed while still under the manufactures warranty period but since they were the first units produced to handle these high thrust loads everybody involved automatically started referring to them as "experimental" after the documentation of failure.
    Without going into the details of "who built this and who signed off on that" the whole mess ended up in court and was settled between the manufacturer, yacht builder and end user but only after the owner had lost the use of his vessel for 14 months or so and a good amount of money thrown to attorneys and at different engineering scenarios for rectifying the problem in a permanent manner. We looked at Aqua drives and Centaflex systems but found that they weren't options for this H.P application. New Z.F. slush boxes, new mounts and brackets along with 2-1/2" and up aluminum billet shim blocks with a short jack shaft on block bearings solved the problem. Good luck with your Huckins Atlantic as I hope that your H.P will allow a switch to Aquadrives or the higher regarded Centaflex units.
    Last edited: Jul 23, 2017
  9. Deer Dr

    Deer Dr New Member

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    Thanks for the details!
    Will research Centaflex.