Gearbox Problems :-(

Discussion in 'Diesel Engines' started by Leela Belle, Oct 25, 2014.

  1. AndySGray
    Joined: Jun 2014
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    Location: Cayman

    AndySGray Senior Member

    Yes, I think from the calc's above, by cleaning the hull
    (and I suspect re-doing the anti-fouling as it seem it isn't working well)
    it will take him into the 30-40% efficiency expected.

    On the current prop he'll be nearer 4 thru 4 and a quarter.

    The 20% more pitch prop MIGHT take him up to about 5.
    All of which is motoring.

    If the main use is Motor Sailing then a higher pitch may be called for to ADD speed from the 3-4 knots windpowered baseline and give the 7 knots the OP is talking about :?:
    Though the motoring side might mean keeping the revs lower when not sailing to avoid cavitation.

    Can't remember where I read it but someone once asked - Are you looking for a motorSAILER, or a MOTORSailer :?:
     
  2. WestVanHan
    Joined: Aug 2009
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    Location: Vancouver

    WestVanHan Not a Senior Member

    RW volunteered,perhaps a larger prop would do.

    He's at 4.5 hp per ton, I'm at about 70 hp per ton...so at cruising,on plane, with a fouled bottom she's only down a few rpm.
     
  3. Leela Belle
    Joined: Oct 2014
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    Location: Tasmania

    Leela Belle Junior Member

    Hi everyone, I know it's been a while since I updated the saga of the Leela Belle, so this is whats happened since I last posted. Just before Christmas I slipped Leela Belle and removed the prop and antifould the hull. Once the prop was put back on and I went back into the water with some what better performance and speed. I attribute this partialy to have a clean hull and the prop being pitched. After a cruise over a weekend it seemed that it still felt under powered so I again slipped Leela Belle and the prop pitched up to 16 x 13 . This seems to have made sufficient difference and she seems to move better through the water. So in short thanks for all your support with suggestions. Its great knowing that there is a vast amount of informative people willing to share there knoqwledge.

    Thanks everyone
    Jerome
     
    1 person likes this.
  4. whitepointer23

    whitepointer23 Previous Member

    Good to see you got it sorted gerome.
     
  5. Leela Belle
    Joined: Oct 2014
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    Location: Tasmania

    Leela Belle Junior Member

    Hi all,
    It's been a whole year since I placed my first post and thought I would share with you all whats happened. On the 24 of November I took Leela Belle to Kettering just south of Hobart and had the engine replaced with a new Vetus M4 35. The transformation has been so amazing. We motored down to Kettering 21 of Nov from Geilston bay. We left at 10am and arrived Kettering at 5 pm, a long slog. However our return trip with the new engine made a huge difference. We left Kettering at 10.45 am and we were on Leela Belle's mooring by 2.15 pm. It cut half the time to get from a to b. the average speed was around 5.5 knots @ 1500 rpm. Any way just wanted to share the news with everyone that contributed to my post and to wish all fair winds and a Merry Christmas.

    Cheers
    Jerome
     
    1 person likes this.
  6. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Congratulation Gerome. It's amazing what a clean hull, straight gear and fresh engine can do isn't it. Enjoy, keep us posted and Merry Christmas to you as well.
     
  7. AndySGray
    Joined: Jun 2014
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    Location: Cayman

    AndySGray Senior Member

    Thanks for the update

    Glad to hear of the successful conclusion.

    I would also like to offer thanks for sharing the results on the forum, it may provide help and direction for future users.

    Have a great Christmas

    Andy

    :)
     
  8. stone beach
    Joined: Dec 2015
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    Location: a

    stone beach Junior Member

    just realised i have posted to an old closed thread !
     
    Last edited: Dec 20, 2015
  9. FAST FRED
    Joined: Oct 2002
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    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    Just wondering if its the same prop being spun at the same shaft RPM , how does a different engine go faster?

    What changed?
     
  10. Leela Belle
    Joined: Oct 2014
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    Location: Tasmania

    Leela Belle Junior Member

    Hi Fred,
    I don't know what caused the change. Just we kept the same prop with no changes , and in fact it was suggested that I have the pitch on the prop reduced as it's pitched a little to much for the new engine. The only thought I have is that the compression in the old motor was pretty bad I don't know. The only thing I can say is I am so glad I replaced it as it makes being out on the water much more enjoyable.

    Cheers
    Jerome
     

  11. FAST FRED
    Joined: Oct 2002
    Posts: 4,519
    Likes: 110, Points: 63, Legacy Rep: 1009
    Location: Conn in summers , Ortona FL in winter , with big d

    FAST FRED Senior Member

    For folks that like to play the prop game a simple rule of thumb is at 1,000 shaft RPM an inch of pitch is about 1K '

    So a shaft speed of 1000RPM would equal 10K , if you had zero slip.

    A good aux. will have perhaps 50% slip .

    Remember the speed of the boat must be taken into account as that (not zero) is usually the speed the prop encounters and gets to push on.

    So a 10 inch pitch might not be far off for a 5-6K boat.
     
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