Modern paddlewheels

Discussion in 'Boat Design' started by Guest, Dec 23, 2003.

  1. WillJones
    Joined: Nov 2003
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    Location: Bahamas

    WillJones Junior Member

    Here are some poor sketches but they give the general idea. I will try a JPEG file. Will Jones
     

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  2. SailDesign
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    SailDesign Old Phart! Stay upwind..

    Will,
    Build it - and they will come. ;-)
    Yipster may be into trying this one - he seems a bit slow getting moving on his trike ... <grin>

    Steve
     
  3. Stephen Ditmore
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    Stephen Ditmore Senior Member

    What has me puzzled here is not propulsive thrust but vertical lift. At a standstill the boat is in displacement mode. As it accellerates does this change? How? The sketch shows the "boat" riding on its wheels alone. Is this because there's upward pressure from somewhere, or is the assumtion that there's enough volume in the [tires?] to support the weight of the vessel as shown?
     
  4. terhohalme
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    terhohalme BEng Boat Technology

    Try first the wheel model at the end of the drilling machine. See if you can find any dynamic lift? Probably you only get a wet mess.
     
  5. yipster
    Joined: Oct 2002
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    yipster designer

    i like WillJones sketch.
    how modern paddlewheels may work is interesting but tax papers, a half build swath trike here and a sundancer is -to me- allready a big order :)
     

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  6. Guest

    Guest Guest

    My objection remains the same and I agree with Stephen. I see no way for the water to exit the scoops other than centrifugal force and that seems as likely to be vertical as horizontal. Lift would only be the momentum of the water moved down by the scoops minus the momentum of the water left in the scoops on the aft side of the wheel.

    I've no doubt that the thing would move forward but, as many have found out in the past, it ain't very efficient and would never lift itself off the water as shown.

    Tom Lathrop
     
  7. duluthboats
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    duluthboats Senior Dreamer

    [​IMG]

    Maybe not a wheel but a belt. This system has it's problems, but this isn't a boat. :eek:

    Gary :D
     
  8. WillJones
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    WillJones Junior Member

    Wow, Gary! A snowmobile running on water. That is amazing. It also proves a point: you can get both lift and propulsion from a track at least. I think it may shift Tom and Steven's intuition a little bit! Now, if a catamaran had two long versions of these tracks... Hmmm, food for thought.

    I still think that a wheel will be best eventually but have not found a perfect link yet. I plan to do some water tests in a day or two. In the meantime, check out this link which has a short video showing the so-called "Jesus Lizard" runing on water - in slow motion, no less. It is very funny but the hydrodynamics are impressive. Note the lack of any wake! Apparently, the creature takes 20 steps per second (is that 1200rpm?) and the feet go quite deep into the water.
    Will Jones


    http://www.visionlearning.com/library/module_viewer.php?mid=57
     
  9. duluthboats
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    duluthboats Senior Dreamer

    :D
    A few years back while sitting on a snow bank sipping sugarcane juice and watching a water skipping contest, I thought why not on a boat. :eek: I think the wheel would be better than a track Hook it up to a snowmobile clutch so you have some slippage as you start off. Than as you start to climb up on plane the paddle will be taking a smaller bite in the water. Put in a reverse gear and you could back off the beach. It would work, would it be better than a prop? I doubt it.

    Gary :D
     
  10. Guest

    Guest Guest

    Sorry, no change in my position. The ski shown is getting lift from both the forward skis and the flat belt with the belt providing the thrust. The belt does provide some lift from its motion due to the fact that it is driving uphill, so to speak. Much more efficient than a wheel since the belt is driving in the forward direction. Now, if you make the wheels so big that the thing floats on only the bottom part of the "tires", it should get better forward drive.

    Never said that the wheel would not work, just that it would not work very well.

    The snowmobile can not go from a dead start in water and needs to get up to speed on land before it enters the water.

    Tom
     
  11. Guest

    Guest Guest

    Incidentally Will, are you sure that this is a snowmobile. Maybe it could be one of the jet skis. I've only seen a few of these and they were very difficult to ride. I know we call them all jet skis but the real ones actually rode above the surface on skis. I watched a guy trying to ride one a few years ago and he kept turning the thing over and falling off. After a couple hours, he gave up. I think it had only a single forward ski so it could bank into turns and be very maneuverable.

    Looking at the pic again, I expect that it really is a snowmobile.

    Actually, I think that this horse is dead and will flog it no more unless someone comes up with a reasonably scientific analysis that shows promise of working.

    Tom Lathrop
     
  12. woodboat
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    woodboat Senior Member

    I am not sure I understand the position against the paddle wheel. High speed surface drives run with half of the prop out of the water. We don't seem concerned about the prop entering the water on a rotation or drag caused by the water not clearing the blade as it exits the water. Granted a low speed tugging contest I would fully expect a standard prop to out tug a paddle wheel but in a high speed app I see little difference. The only difference that stands out is that a prop flying half out enters the water partially at first where a clssic paddle enters all at once. As far as the snowmobile and this statement "The snowmobile can not go from a dead start in water and needs to get up to speed on land before it enters the water" well that just proves the point that the belt provides lift. See a snowmobile sinks like a rock in water unless it is up to speed first, it isn't a boat afterall. As far as real world stuff there is a local paddle wheeler, classic looking paddles but with a modern engine. It travels to boat shows. The boat is capable of speeds in excess of 50 MPH with a single small block Chevy. This is faster than my traditional inboard of similar size and power which only runs about 30 Mph. Now I am not suggesting that I believe paddle wheels are superior but that they simply should not be dismissed as ancient, obsolete propulsion.
    Rob
    AKA
    Woodboat
     
  13. Guest

    Guest Guest

    Nobody said that Rob,

    Go back and read the whole thread. It is about a pelton wheel turbine acting to both support and drive a boat clear of the water.
     
  14. woodboat
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    woodboat Senior Member

    I may have read into the responses too much. The original question is "My question is: "Has any work been done recently on paddlewheel propulsion?" Then the discussion turned to the pelton wheel. My point remains that the fact that a snow mobile which would otherwise sink at rest can maintain bouyance at speed suggests that the track provides substantial lift and actually very good speed. I have also seen 4 wheel drive trucks drive straight across a small lake. The tires did not in and of themselves provide the bouyancy needed yet the rotation of tires acting like four paddle wheels provided lift and propulsion. I of course lack scientific evidence and am mearly pointing out real world facts. Any way I'll go back to lurking.
    Rob
     

  15. SailDesign
    Joined: Jan 2003
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    SailDesign Old Phart! Stay upwind..

    Rob says "Any way I'll go back to lurking."

    Don't just do that, Rob. It is only by having people ask questions that these places function. If it was only us old industry farts in here, it would be boring indeed, as we are all pretty much set in our ways, and it is nice to have new blood to arg.... I mean "discuss" things with. (Phew!)
    One thing about forums, as well as Usenet (newsgroups) is that you have to develop a thick skin. No-one really knows who anyone else is, and credentials are hard to ascertain, so you rarely know who is who anyway.
    Steve
     
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