Modern paddlewheels

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

  1. woodboat
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    woodboat Senior Member

    Thanks for the kind reception. I am very familiar with the strength of a community forum as I participate in a video editing forum daily. I am a little out of my league with boat design however. I did grow up on the Chesapeake bay thus have that brakish water running through my veins :) SO I have seen what works in real life yet lack the education in theory. I find this discussion board very informative.
     
  2. Guest

    Guest Guest

    I followed up on Gary's lead on snowmobiles skipping over water. What a revelation: apparently, there is a whole subculture out there that does this stuff!!

    The world record is said to be 100 miles at an average speed of nearly 60 mile per hour using a 580cc engine and getting nearly 8 miles per (imperial) gallon ! That sounds quite efficient to me - especially considering it is probably a highly tuned 2-stroke engine. Check this link.

    http://www.biedaspowersports.com/henry.html

    It also seems to address Tom's point: this pic shows the vehicle with the skis out of the water and running just on its tracks - at least intermittently.

    Woodboat: Do you have any pics of the fast paddlewheel boat?

    I think an experiment or two is now needed to prove or refute the concept. I will build a rig over the next few weeks if I get time. My guess is that the wheel will need a stationary deflector or volute to keep the output flow horizontal, but it should work OK. I will let you know my results. In the meantime: Happy New Year to all.
    Will Jones
     
  3. woodboat
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    woodboat Senior Member

    I do not have photos. I saw it at a local festival in Fells Point, that is near downtown Baltimore. There were photos of it at speed and some specs. I could be slightly off but I am usually pretty good with specs. The pictures showed a boat hat appeared to be moving quite fast, easily in the 45 MPH range. I would think a belt system the width of the boat but just shy of the stern, say maybe one foot, and very close to the hull should allow any water ejected from the belt to exit the stern for added push. If it had very shallow tread then power should not be used up making the "paddle" enter the water. It should skip more like a snow mobile. I also know that the truck competition is held in iceland. They try to see how far a 4 wheel drive will travel across the lake before it sinks :)
     
  4. Guest

    Guest Guest

    The snowmobile does not stay up by using lift.

    In general the back sinks faster than the front. It stays up by climbing up the hill (shear power).

    With no offense intended ...

    It is important to design for the proper paramaters - Reynolds, Euler, Froude, or Strouhal numbers.

    A lot of design work involves making those parameters right. In the case of the snowmobile or a very large pddle wheel, enough cross member area reduce the local stress on the water so that the water "does not" move rather the cross members see the water as a solid and act accordingly.
     
  5. woodboat
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    woodboat Senior Member

    Not that this is not the proper place, cause it is but isn't your version of lift almost symantics? We would all agree that a Hydrofoil creates lift, yes? I would agree that because a belt system does not meet the criteria for "lift" that it may not be a proper term. The real world effect though is that regards of the hill effect, the jesus lizard or whatever the craft obtains lift through the motion of the belt and/or paddle. Also the fact that the snowmobile can achieve speeds of 60+ MPH with a 500 CC rotax engine also suggests that it is efficient. Now I don't know how practical it would be for say a 40 Ft craft with a full lenght moving belt system but it certainly sounds interesting.
     
  6. Guest

    Guest Guest

    woodboat ---

    Consider the following design.

    A boat that floats and a propulsion system where blades are dropped into the water at the bow, conveyed to the stern, pulled out, and recycled.

    There is no lift in this system. "Lift" was a necessary artifact of the snowmobile not floating.

    If we redesign the blades so they sit on the end of shafts extendout out of the two sides of the boat, be have a traditional row boat, canoe, kayak, or Roman warship.
     
  7. woodboat
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    woodboat Senior Member

    I not only don't understand your modern roman warship I also can't tell if you are being sarcastic. I also conceded that a literal definition of lift does not apply to the snowmobile but that real world application=effective lift, what shouldn't float fails to sink.
     
  8. tonyvv
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    tonyvv New Member

    Well, I have seem a snow mobile cross a river, and they all did not make it. These snowmobiles have very powerful high hp/ low weight engines. Something like 120 to 200 hp on a very lightweight frame. They will go very fast on snow. Put half that power in a prop and the small boat like pwc and it will 100 mgh.

    Paddlewheels as they spin do not produce lift, they produce suction in front and just below as water enteres to fill empty area. If you spin it faster it will suck itself all the way down. The only way to avoid this is to spin a closed wheel very quickly and letting the surface tension and whatever the name of the effect of spining objects do propulsion. I think the life on this would still be balanced out by the suction created...

    Tony
     
  9. gonzo
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    gonzo Senior Member

    A good example of lift on tires is the hydroplaning effect on a car. Millions of dollars are spent to avoid it. Woodboat: there is not such a thing as "hill effect". The track of a snowmobile provides lift because the direction of travel is aft and down. How do you define lift, and why are you making a distinction with "real world"?
     
  10. woodboat
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    woodboat Senior Member

    Gonzo, I don't have a clue. The guest before stated that the snowmobile was climbing a hill not creating lift. I was simply conceding to move on. Rather than argue about something I construed as symantics I came back to what I thought still might be a viable propulsion system. I thought some might make the distiction between lift as created with a wing versus thrust that might be created with say a prop pulling a plane vertically. Granted in that analogy the prop it's self creates lift but thrust creates vertical movement. Back to real vehicles for a second. The seadoo is essentially the same size and weight as the snomobile. They use the same rotax engine. With the same displacement/horsepower the PWC does not come close to the snowmobile. The original Yamaha wave runner did 31 MPH. Granted new ones will do 60 MPh but horsepower has grown immensly. I am not convinced that a water jet is more effecient then a track belt system.
     
  11. WillJones
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    WillJones Junior Member

    I have just run a crude test of a high-speed wheel by attaching a plastic "all terrain" wheel from a model truck to a Dremel motor tool. It works surprisingly well at about 3000rpm. The water is ejected in a largely horizontal direction - although there is a "rooster tail" and a lot of mist. But the thrust can be felt as well as the lifting force. The wheel appears to claw its way out of the water.
    The wheel works better in the direction that the cleats form a cup rather than the reverse. However, putting sides on the wheel to prevent loss of water in that direction would improve it a lot, I believe. Also, the cleats are rounded and a harder edge would grab more water.
    Note: The Dyson "Wheelboat" described in my earlier posting did 60kph (35mph) on land and on water.

    Will Jones
    PS: I hope this post records my registered name this time!
     
  12. yipster
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    yipster designer

    wont be easy beating that mighty prop, yet multiple interesting insights came forward. a century ago 2 steamships, one a paddler the other propped were roped up on their sterns and helt a contest my tv says. the padler was of first but than the screw pulled it away. pushing<>pulling? i find it interesting to hear and see paddlewheels since than devellop. who knows, they went into oblivion yes, but i'm not so completely convinced their role is played out.

    same james dysons as from the attached paddlewheel drawing?
     
  13. woodboat
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    woodboat Senior Member

    yipster, I would fully expect a prop to out tug a paddle wheel. What I think has come to light, at least for me, with this discussion is how the test changes when you think about a high speed craft skipping along the water. I never realized that the snowmobile could maintain that rate of speed for that distance. That is a far cry from a riverqueen paddle wheeler. However the arrangement, if the system for propulsion is virtually the only thing in contact with the water you have greatly reduced drag.
     
  14. tom kane
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    tom kane Senior Member

    There have been many ideas using paddle wheel principle for high speed work,hoping to reduce drag etc.,vertical and horizontal single and double working together.Some have incorporated two cone shaped wheels inside of a housing.The diagram shows an old (because they are simpler) outboard motor mounted sideways on a transom,but still able to turn,which I have found cheap and quick to play with.
     

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  15. SamSam
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    SamSam Senior Member

    I found this in the USPTO site. There is a bunch more drawings at the site itself with explanations on how it works. It's a feathering wheel, the arms on the paddles, #3, and the cam, #4, working together to accomplish feathering with the crank on cam #4 being used to adjust the feathering action. As far as feathering goes, this system seems to be pretty reasonable and possibly usable compared to some Rube Goldberg contraptions I've seen. There is a simpler feathering system I found once that seemed pretty workable also, if anyone is interested I could probably find it again. The claim was it was 50% more effecient than a regular paddlewheel. As for this high speed wheel,my guess is it wouldn't work. It seems would just cavitate, or "dig a hole" or whatever paddlewheelers say. Being issued a patent doesn't mean a thing will actually work, sometimes it means you are pretty sure it will work, at least sure enough to give them enough money to issue you a patent.
     

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