Concerning feathered paddlewheels...

Discussion in 'Boat Design' started by Village_Idiot, Feb 20, 2013.

  1. Village_Idiot
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    Village_Idiot Senior Member

    Those who have frequented this forum for a number of years are likely familiar with the design of the feathered paddlewheel (if not, a quick google image search should bring you up to speed). The mechanisms used to feather the paddles look to be less than robust, and not very elegant to boot.

    I was recently looking at some various engineering designs, and came across info about a "reading wheel" designed by Italian engineer Agostino Ramelli, as well as a supposedly improved design by French inventor Grollier de Serviere (see Wikipedia). As far as I can tell, these designs use planetary gearsets in their mechanisms, but there are no details that I can find.

    I wonder if such a setup would provide for a more robust feathering mechanism in paddlewheels? Does anyone know if this has been tried, or some other type of planetary gear mechanism has been used for feathering paddles? Could it possibly give resurgence to paddlewheel design?
     
  2. jehardiman
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    jehardiman Senior Member

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  3. Village_Idiot
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    Village_Idiot Senior Member

    Thank you for the link!

    Although unclear, it appears as though the answer may be in the statement "A large strap, rotating on a fixed eccentric around the inboard shaft bearing of the paddlewheel, involves more lubrication problems and does not lend itself to shifting its position at a later date." on page 647. However, I wonder if those limitations can be overcome with modern design and technology, and are there redeeming qualities to a planetary mechanism (mostly in strength) that would mitigate for those limitations?

    What is clear is that much improvement can be made to paddlewheel trimming and paddle feathering, and that can be accomplished with modern technology. Likely, the demand isn't there to see it through, however.
     
  4. upchurchmr
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    upchurchmr Senior Member

    Pictures, I dont' follow anything without pictures - ignorant Engineer here.
    Honestly, I don't understand the references.
     
  5. Village_Idiot
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    Village_Idiot Senior Member

    Simply go to google.com, click on images and type "reading wheel" into the search box - you will get lots of images. I would post one here, but would probably run afoul of copyright laws or somesuch...

    The idea is to use a planetary gearset off of the main shaft, whereby the smaller planetary gears would position the paddles so that they remain vertical in the water at all times. There are potential advantages over the external linkage design that has been utilized in the past, but the question is whether those advantages exceed the disadvantages.
     
  6. SamSam
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    SamSam Senior Member

  7. Village_Idiot
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    Village_Idiot Senior Member

    Interesting, but I would have to see it to believe it, especially at varying speeds.
     
  8. upchurchmr
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    upchurchmr Senior Member

    I really don't care about some miscellaneous image.
    You wanted to talk about a particular mechanism.
    I can't talk about something I have only seen in words.

    Waste of time.
     
  9. fredrosse
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    fredrosse USACE Steam

    Having recently built a sidewheeler, and having reviewed much technical data, it is clear that paddle wheel propulsion is a fairly efficient setup, rivaling screw propellers if fitted with feathering wheels that are properly designed.

    The mechanisms of old work well to achieve reasonable propulsion efficiency, however the inherent problems of a sidewheeler will be there with or without a fancy new feathering mechanism.

    These issues are: paddlewheels take up lots of room, make docking difficult, and there are many articulated joints in the water. Boat draft changes hurt efficiency, but not really an issue on pleasure boats with articulated wheels. Rough water immediately halves the boat speed, and doubles the power requirement.

    The articulated joints can work well with UHMW bearings, and the shallow draft only available with paddlewheels is very nice for some applications. I am very happy with my sidewheel steamer, and would think a planetary gear system would introduce unnecessary complication.
     
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  10. upchurchmr
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    upchurchmr Senior Member

    Fredrosse,

    How about some pictures? Can you / will you show the mechanism for the feathering wheel?
     
  11. SamSam
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    SamSam Senior Member

    Yeah, looking at pictures of the feathered wheel mechanism, it is a bit complicated and must weigh a lot. I found a picture of the Agostino Ramelli reading wheel planetary gears system and that would be a load in itself. Keeping the things lubricated would be an engineering feat in itself. Comparing images of the two systems, of Agostino Ramelli and Grollier de Serviere, I have to say Ramelli's is much more sophisticated but maybe that's just because the cover is removed and all the mechanicals are exposed and understandable whereas the picture of de Serviere's doesn't show much of the mechanism that makes it work.
     
  12. fredrosse
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    fredrosse USACE Steam

    The attached sketch shows a typical late 19th century feathering wheel mechanism, and the new mechanism detail, currently being built for my sidewheeler. At present I have non-articulated wheels, and the new wheels will turn faster, allowing considerable engine power increase, as well as more efficient propulsion. I expect a 20% increase in boat speed with the articulated wheels, with wheel speed going from 52 RPM up to about 70 RPM.

    There are a few videos of the sidewheeler on this forum.
     

    Attached Files:

  13. Number4

    Number4 Previous Member

  14. upchurchmr
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    upchurchmr Senior Member

    Many people can make something that works, but not that works particularly well.
    No way to tell how fast vs how much horsepower.

    Any one know what that large brown square lump is between the paddles? Extra flotation for a boat that got too tail heavy?

    What I notice is the quantity of water that is picked up behind the paddle. lifting water up 1-2 feet has to waste a lot of thrust/ horsepower. An articulated paddle "should" reduce that inefficiency.
     

  15. fredrosse
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    fredrosse USACE Steam

    upchurchmr is very correct here, when you have a big V8 engine with gobs of power on a moderate skiff, propulsion efficiency is not so much an issue on youtube videos. For my sidewheeler, with very limited power, the improvement in propuldion efficiency is large. Being able to pick up 20% boat speed with proper articulated wheels is very significant, although the speed increase is not entirely due to the articulated wheels. The articulated wheels also allow my steam engine to make more power due to higher engine speed.
     
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