Prop shaft powered alternator for cruising sailboats !

Discussion in 'Sailboats' started by Angélique, Sep 29, 2017.

  1. Angélique
    Joined: Feb 2009
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    Angélique aka Angel (only by name)

    This new thread is a split-off from the thread: What makes the best offshore cruising yacht

    This to avoid further thread drift there, so each thread can stay concentrated on its intended topic.

    The quotes in the post #1 here come from the linked thread.

    To see a quoted post in its original context click on the in the header of the quote.

    See also the thread: Windora's - Refit
    [​IMG]

    [​IMG]
    Click on the thumbnails in the quotes for an enlargement, and click again to shrink them.
     
    Last edited: Sep 30, 2017
  2. Nick.K
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    Nick.K Senior Member

    How about a washing machine pulley? Most I've seen are ribbed belts not V but then so are many alternators. No fan though but plenty of scrap ones to choose from in any recycling centre:)
     
  3. Phil Christieso
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    Phil Christieso Junior Member

    Well done you lot
    I bored out the 400 mm dia. pulley hub then machined a taper lock from 316 s/s
    There's no key its not needed
    Then grit blasted the pulley and epoxy painted it
    Machined a 50mm dia. s/s double z section pulley for the alternator.
    The alternator is a standard 65 amp
    It's been running now for 8 years and 40,000+ NM's
     
    Angélique likes this.
  4. Angélique
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    Angélique aka Angel (only by name)

    Some more breakers, so be careful about the pulley you choose . . .​

    [​IMG]
     
  5. Angélique
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    Angélique aka Angel (only by name)

    The hub of most household washing machine pulleys might be of a too small diameter, not enough "flesh" on the hub, to make it fit for the mounting system on the prop shaft I think.
     
    Last edited: Sep 29, 2017
  6. Angélique
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    Angélique aka Angel (only by name)

    Here's an eBay check for air compressor pulley, every now and then there might be a used classic one listed there.

    Also could check Craigslist and similar sites for this.
     
    Last edited: Sep 29, 2017
  7. Angélique
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    Angélique aka Angel (only by name)

    A split pulley made in semicircular halves for ease of applying and clamping to the prop shaft might be an idea, aka parting pulley, they used to be made of wood to run long flat belts . . :cool:

    The multiple V-belt split pulleys below are only pictured here to illustrate the split pulley idea . . .

    [​IMG]

    [​IMG]
    source - single V-belt split pulley

    [​IMG]
     
    Last edited: Sep 30, 2017
  8. Angélique
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    Angélique aka Angel (only by name)

    Prior to the advent of inexpensive electric motors, entire factories and workshops where powered by series of long shafts, with often wooden split pulleys clamped everywhere on them, and long flat belts running to every powered machine in the entire building. It was quite dangerous as all of this was unprotected back then. It was also prior to the advent of the OSHA and similar agencies in other countries.

    So watch out for yourself when you're down in the bilge, checking on the rotating prop shaft powered alternator with a running belt and a spoked pulley turning, since the OSHA and the like don't watch over you there . . !
     
    Last edited: Oct 1, 2017
  9. Nick.K
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    Nick.K Senior Member

    You would probably have to make a split collar for the shaft in any case. The pulley could be bolted to the collar. Some of the images of washing machine pulleys on Google look like they could work such as this Indesit part.
    [​IMG]
     
  10. Angélique
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    Angélique aka Angel (only by name)

    The way you've described it, with that different way of mounting, a washing machine pulley looks to me like a good option Nick . . :)
     
  11. M&M Ovenden
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    M&M Ovenden Senior Member

    Hi Phil,

    I was wondering if you had measured the RPM of your shaft while sailing. We will have a very similar prop on our boat (diameter and pitch) , so it's a good starting point. Looking at some power curves of alternators and comparing to your numbers I'm guessing it's spinning at around 1500 RPM, and with your pulley ratio the shaft is somewhere in the neighborhood of 200 RPM.

    Thanks ,
    Mark
     
    Last edited: Sep 30, 2017
  12. Phil Christieso
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    Phil Christieso Junior Member

    P1300914.jpg
    Look what I found the drawing I made for the taper lock
    It's a long time now since I measured it I thick 250rpm@7 knots.
    Also when charging all the shaft runble and prop noise stops totally.
     
    Last edited: Oct 2, 2017
  13. M&M Ovenden
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    M&M Ovenden Senior Member

    This is interesting. So from what I understand if you have the alternator field off (not generating) there is rumble , but when you turn it on the load on the shaft makes everything quieter ?
     
  14. Phil Christieso
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    Phil Christieso Junior Member

    Yes that's right, much quieter plus it lowers the shaft rpm with load.
     

  15. Angélique
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    Angélique aka Angel (only by name)

    This is what I'm thinking of . . .

    The boat is pulling the prop, and the prop is free spinning in the no charging mode, any waves coming from aft might give the prop a temporarily push, now if there's any forward backward play on the prop shaft, then each of these temporarily pushes from aft might cause a temporal change in the position of the forward backward play on the prop shaft, as by each little push from behind the play briefly changes from pull to push position, causing a continuing series of some backlash on the prop shaft, which can be heard as prop shaft rumble.

    Now what differs on each type of boat is that the prop find itself in a more or less turbulent area behind the keel, and that the keel drag might cause some reverse current in the prop area, which might have a worsening effect on the above described prop shaft backlash and rumble issues, as the keel drag turbulence causes a less constant pull on the prop.

    When changing to charging mode there will be more pull from the prop on the prop shaft, so if there is now any little pushes by from aft comming waves on
    the prop, and/or some turbulence in the prop area, the pull of the prop on the prop shaft will be larger then the little pushes from behind, so there will be no prop shaft backlash and rumble issues any more, since the forward backward play on the prop shaft now stays in the pull position all the time.
     
    Last edited: Oct 6, 2017
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