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  1. #1
    Join Date
    Aug 2013
    Location
    SW Scotland
    Posts
    19,385

    Default Screaming sterngear

    Yesterday afternoon my sterngear started producing a high pitched scream, so even and constant in tone that I thought it was an electronic alarm. It first happened with the engine running, then under sail - in the latter case engaging reverse gear to lock the prop stops it instantly. It doesn't happen all the time and seems only loosely linked to boat speed - under sail it would appear and disappear between four and six knots.

    Stern gear as traditional cutless bearing, hose, ungreased stuffing gland. No extra leakage. Sound is like a finger round a wineglass, but loud. Rubber of cutless bearing squealing?

    Any advice, ideally based on similar experience, welcome.
    "Seamen are always wanting to do things the proper way; and I like to do them my way."

  2. #2
    Join Date
    May 2001
    Location
    North Wales, sailing Aegean Sea or Menai Strait
    Posts
    21,850

    Default Re: Screaming sterngear

    I assume not a new prop? It sounds rather like the ringing that occurs with sharp trailing edges on props (and Hobie cat rudders!)
    Answers to some technical queries at new website http://coxeng.co.uk

  3. #3
    Join Date
    May 2007
    Posts
    37,274

    Default Re: Screaming sterngear

    Could be damaged trailing edge of prop as Vyv suggests?
    Or ungreased stuffing gland scraping on shaft, resonance dictated by rubber hose?
    Does it do it in astern?

  4. #4
    Join Date
    Aug 2006
    Location
    NE Coast
    Posts
    1,589

    Default Re: Screaming sterngear

    As it happens 'with or without' the engine running I agree with above and have a close look at your stuffing box
    Archivist for the Colvic Watson Owners Group

  5. #5
    Join Date
    Aug 2013
    Location
    SW Scotland
    Posts
    19,385

    Default Re: Screaming sterngear

    No recent changes. Did 7 hours to Crinan Canal plus transit without issues. What I can see of the stuffing box looks fine. Access is atrocious. Lack of leak suggests to me that the stuffing is doing its work. Anyone know which of Crinan Boats, Kilmelford, Kerrera has the skinniest mechanic?

  6. #6
    Join Date
    May 2007
    Posts
    37,274

    Default Re: Screaming sterngear

    As well as damage to the prop, I'd look for rope etc around the shaft before getting a mechanic in.

  7. #7
    Join Date
    Nov 2008
    Posts
    6,856

    Default Re: Screaming sterngear

    I had precisely that, many years ago, with a Folkboat. I had drawn the shaft out in the winter, and as a result, grease from the stuffing box was carried back to the Cutless. The grease evidently reacted with the rubber, softening it, and the rubber then started sticking to the shaft. Had to replace the Cutless.

  8. #8
    Join Date
    Aug 2004
    Location
    Cumbria; U.K.
    Posts
    3,289

    Default Re: Screaming sterngear

    Could be mistaken, but I have a (very) distant memory of someone else complaining of this problem, the cause being nylon fishing line round the shaft and into the cutless bearing.

  9. #9
    Join Date
    Jun 2019
    Posts
    27

    Default Re: Screaming sterngear

    I would think you have dried out the stuffing in the gland. It needs an odd drip to keep it lubricated and as you say its an un-lubricated type there is no chance to push some grease in. Really needs the stuffing pulled out and some new installed as the original will have burnt/hardened which is why its screaming.

    Of cause nylon will scream, it doesn't like salt water so any sort of bush will tighten onto a shaft and become tight or worst seize up. Many manufacturers that should know better use nylon for all sorts. The twin rudders under Sun 2500's as an example, If they are stiff the chances are its got nylon bushes supporting the shafts. Should be nitrile but its more expensive.

  10. #10
    Join Date
    Aug 2013
    Location
    SW Scotland
    Posts
    19,385

    Default Re: Screaming sterngear

    Many thanks, all. Panic - or at any rate mild apprehension - is over for now. We motored a solid three hours from Ardinamir to Kerrera today with no reoccurrence. It was too choppy to inspect the shaft from above yesterday, but my crew lowered a waterproof camera down and reported something like string or seaweed streaming from the prop. My working hypothesis is that we picked up something (nylon fishing line?) round the shaft which obstructed water flow into the cutless bearing and caused it to squeal. Some hard astern on arrival then dislodged it.

    Of course a hypothesis which requires no action is dangerously attractive, but for now I am relaxing, a little, though I'll continue to monitor the situation. The cutless bearing is ten years old and due for replacement next winter anyway, but there seems to be no increase in vibration. Yet.

    Incidentally, if it wasn't for the woeful electrics and dreadful after sales service, I could warm to this engine. Seven hours from Bute to Ardrishaig and a canal transit used almost exactly eight litres of fuel in ttal. That's about half what the previous 1GM10 would have used.

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