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Discussion in 'Boat Design' started by Guest625101138, Jul 14, 2008.

  1. Dave Gudeman
    Joined: Nov 2009
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    Location: San Francisco, CA, USA

    Dave Gudeman Senior Member

    wheel paddles

    This is probably going to sound a little wild, but for dealing with shallow water, why not design the paddle wheels to also act as wheels? I'm not talking about anything that could handle long distances --just enough to get up on a beach or to launch from a muddy bank without having to step in the mud.

    I'm also not talking about tires with ridges. Those don't look like they are very efficient at water propulsion. You want to compromise on land propulsion, not water propulsion, so you want a good paddle wheel first.

    I can think of several ways to do this. If the paddle wheel is a broad stern wheel with paddle boards held between two rims then you could put tires on the rims. The tires would stick out just an inch or two beyond the paddles. They would add a bit of weight, but I don't think it would make the boat less efficient otherwise.

    Alternatively, if you have two side paddle wheels, then maybe something like a bicycle tire with the paddles sticking out the sides. Again, the presence of the tire shouldn't add any inefficiency beyond the additional weight.

    There is another possibility for the side paddle wheels. I wonder how it would work if there were a thin tire over the whole wheel the same width as the paddles. In other words, the paddles would effectively be wide spokes in a wide wheel. This would probably reduce efficiency, but it might not be so bad. You could put a gap in the wheel at the leading edge of each paddle for water to flow off the end of the paddle as the paddle leaves the water.

    You may need to have multiple gears in order to peddle both the paddle wheel and the wheel.
     
  2. portacruise
    Joined: Jun 2009
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    Location: USA

    portacruise Senior Member

    The efficient paddle wheels which I have seen would be compromised significantly if also acting as rolling wheels. Here's the hpb site which show various fast paddlewheels with a little browsing http://www.humanpoweredboats.com/Photos/UniversityDisplacementHPBs/UniversityDisplacementHPBs.htm
    hydrodynamosaurs, clementine, etc. I like TUHHsneda because it works using water friction instead of having to fight this friction for speed. Generally paddlewheel systems have the disadvantages previously mentioned, plus a higher profile which introduces more wind resistance and being more prone to damage at shallow conditions than say a flex prop shaft. Wide tires would be the most versatile because they would handle difficult shallow water conditions like rocks or soft mud while having an easy time with hard pack or sandy bottoms. Here a clip showing what can happen when running over a rock in shallow water with the ideal wheel shape: http://www.youtube.com/watch?v=YxkXzjHsCx4&feature=related

    Hope this helps.

    P.


     
  3. MLampi
    Joined: Aug 2008
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    Location: Bellevue, WA

    MLampi Junior Member

    The paddles on my canoe's paddle wheels extended only about 5 or 6 inches into the water. There were enough blades around the 27" bicycle rim that when I did accidentally encounter a sand bar on one side it merely lifted the canoe up and over the bar.

    There was for a couple of years a company in Port Townsend, WA that sold copies of their amphibious side wheeler canoe. They used standard bike wheels with blades near the rim for water propulsion and tires for hard surface propulsion.

    I think there are some photos on the www.humanpoweredboats.com web site.

    Michael Lampi
     
  4. cutyourway
    Joined: Dec 2010
    Posts: 9
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    Location: Austin TX

    cutyourway Peter STANLEY

    re paddle/tired wheels

    Yes I agree and am passively developing such a system. I have most of the parts, so I just need a little bit more space, vision, and motivation.

    The idea of putting tires on the paddle wheel is great except for a few problems I can think of:

    • I want my paddles to radiate FROM the rim, to maximize paddle radius and further approach linear motion. If I am to maintain this design feature, then the tires and paddles must independently retract.
    • The surface area of the tire will generate bouyant force, and parasitic drag. These forces may be negligible for an innovative craft, and I'm imagining that this craft should hydrofoil as much as possible... In this case, maybe tires are a great feature, since dirtbikers and ATV'ers have mastered hydroplaning!
    • Any high-quality tire besides 20" can get pricey. Any 26" tire worth mounting starts at $30, where my favorite 20" is only $15.

     
  5. Clemens
    Joined: Jan 2010
    Posts: 14
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    Location: France

    Clemens Junior Member

    New platform for cruising seacycle

    Hello TT,
    finally finished my summer project. The new platform is attached to the garage's ceiling, ready for future expeditions.

    My goals:
    • to reduce weight
    • to reduce number of parts
    • to enlarge area of platform for bigger tent

    It took a lot of effort, though.
    I worked with foam, with carbon and glass fibers and with epoxy resin.

    Dimensions of the new platform:
    2,40 x 1,60 x 0.12 meters, the front beams protruding another 0.6 meters.

    Best greetings,
    Clem
     

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  6. spidennis
    Joined: Feb 2007
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    Location: south padre island, texas

    spidennis Chief Sawdust Sweeper

    Very nice Clem!

    What kind of trips and performance have you got going?
    I'm thinking about using a similar system on my Ultimate Florida Challenge boat and can't wait to start trying this all out. got more pics? What drive are you using?

    I wonder how this system would work out mounted off the back cross spar/beam, facing backward, peddling backwards? I don't have a lot of room and that would keep the "human powered outboard" out of the way as best as possible.
     
  7. Clemens
    Joined: Jan 2010
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    Location: France

    Clemens Junior Member

    Hi Spidennis,
    I'm planning further multi day excursions on the french canals, on Lake Konstanz, in the lake district "M├╝ritz" in Germany.
    Floats, yokes, drive units and rudder are original seacycle parts.
    Cruising speed is roughly 6-8 km per hour, once I covered a distance of 45 km in one day.
    Best greetings
    Clem
     
  8. Tiny Turnip
    Joined: Mar 2008
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    Location: Huddersfield, UK

    Tiny Turnip Senior Member

    Hi Clem - its looking good!
    I still haven't slept out on my boat, but as soon as it gets warmer, we're going to give it a go!
     
  9. zipboater
    Joined: Nov 2010
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    Location: Mandeville, Louisiana

    zipboater Junior Member

    i am about two more weeks from having my new drive concept ready to test. I will be posting a video of the results(with gps speed data) on youtube. so far so good. i think you guys are about to see a new way to haul *** on the water. i'm like a kid with a new toy. the weather has been a factor in finishing this project. I'm building this thing in my back yard. My carport is alreadyt full and I'm juggling a lot of other plates. Portacruise, things are looking good for the 2013 race season.
     
  10. I57
    Joined: Feb 2008
    Posts: 172
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    Location: Melbourne, Australia

    I57 Senior Member

    Stabilised Monohull

    This forum has been quiet for a while, thought I might put in my news. My stabilised monohull has been undergoing constant changes. I have removed the dipping rudders and replaced them with a rudder. I use a small 100mm x 100mm one for at the lake where I have more room to move, and a larger one for on the river where I need to turn quicker. Have put in a straight 16mm aluminium shaft, angled at 16deg. and tried a couple of different props. Even snapped off a blade when doing a speed run, came back with a one bladed prop. It was a home made fibreglass prop, and is the first one to break. Have a four blade prop, the first time the cord was to narrow and spun too fast so beefed it up and could hardly turn it. Now have trimmed it back so should be ok, one advatage of a fibreglass prop you can reshape and resize easily. Have lowered the gearbox and made a cutout on each side of the hull for my feet. This has enabled me to lower the gearbox and seat by 100mm and the shaft angle has improved to 11deg. See how it goes when I finish the work on it.

    Ian
     

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  11. Dennis A
    Joined: Aug 2009
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    Location: Amersham bucks uk

    Dennis A Junior Member

    Hi Ian
    I had a similar problem of over revving due to prop slip of up to 30%. To cure the problem I doubled the cord width but then struggled to turn the prop on the faster runs. My boat is very similar to yours and had a max sprint speed of 11.2 kph.
    How much are you proposing to trim back the prop.

    Did you take any action on the tilting prop idea.

    Dennis
     
  12. I57
    Joined: Feb 2008
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    Location: Melbourne, Australia

    I57 Senior Member

    Props

    Dennis
    The four blade prop was 20mm cord with a 400mm dia, this was much to light so beefed it up to 40mm cord and could hardly turn it. Have now made the cord 30mm but have yet to try it out. Have just finished modifying the boat whereby I have lowered the gearbox by making cutouts in the hull for my feet. The shaft angle has improved to 11 deg. and have also moved the outriggers further aft. Hope to get it on the water next week to see how it goes.
    I managed to get to 12.5 kph with a two bladed prop before I broke it. Tried out one of Ricks folding props and flex shaft last week and got to 13.7kph. See how it goes with the better shaft angle and using a rigid shaft. I couldn't find any details on the tilting prop, an interesting idea.

    Ian
     

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  13. Dennis A
    Joined: Aug 2009
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    Location: Amersham bucks uk

    Dennis A Junior Member

    Swivelling Prop.

    Hi Ian
    Here is a simple sketch of the swiveling prop design. The only one I know of was 2 bladed with prop from bronze and shaft from steel, but I understand that this system is used on 2 bladed helicopters.
    It uses the same princples to ensure that the prop is verticle as Ricks curved shafts.
    I have not tried itas I find the use of a folding prop & a curved shaft is unbeatable.

    Dennis
     

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  14. I57
    Joined: Feb 2008
    Posts: 172
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    Location: Melbourne, Australia

    I57 Senior Member

    Swivelling Prop

    Dennis
    Looks like the swiveling prop works in the same way as a universal joint. The fixing pin would have to be fairly strong as it would have a large shearing force acting on it. On my first boat I used a universal joint to get the prop vertical and managed to break a couple of them. The larger the angle of the shaft the greater the load and the bigger the pin. I had a 11 deg angle on the shaft and it was not a smooth action, could feel the joint clunking around.
    Making the hub could be difficult as each end would have to be a cone shaped hole angled to the same angle as the shaft. Alternatley a tube with an internal ring which the prop would rotate around, this would be easier to make but would it work as well?

    Ian
     

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  15. Jeremy Harris
    Joined: Jun 2009
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    Location: Salisbury, UK

    Jeremy Harris Senior Member

    I have used a double universal joint to turn a propeller shaft through a large angle (80 degrees) quite successfully. The joints do need to be massively de-rated as the angle increases, though. For example, at 45 degrees the joint can only withstand 0.25 of the torque that it will operate at when at 10 degrees. The joint I used was made by Lenze (see here: http://www.techdrives.co.uk/html/universal_joints.html) and although I used the plain steel version I believe they do make a stainless one. The double universal has the advantage of being constant velocity at both ends, so gives smooth drive with no pulsing. I have found that a 10mm bore double joint running through 80 degrees and driving a 320mm diameter two blade prop seems to work OK, although I am running at higher rpm than your pedal application (up to 680 rpm maximum) so the torque is lower.

    Jeremy
     
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