Hand Paddle Boat Design

Discussion in 'Boat Design' started by mahak213, Nov 13, 2012.

  1. mahak213
    Joined: Nov 2012
    Posts: 1
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: New York

    mahak213 New Member

    Hey,

    I'm working on a team for a senior design project and was hoping that this community could offer some insight and input in regards to a design we are working on. Our task is to retrofit an aluminum flat bottom boat with a hand-crank system that allows disabled individuals to participate in boating activities. The range of disabilities is very wide, as is the age of the individuals that will be using the boat, so one constraint is that the design must be as user friendly and adaptable as possible. The only assumption we've made is that the individual using the boat has enough strength to adequately turn the hand cranks. Additionally, the modifications we make must be easily removable. I've attached a picture of the boat we have been given to modify. Our plan is to attach paddle wheels to the sides of the boat that will be powered via hand paddles. Each wheel will be given it's own crank near the side of the boat so that the center of the boat is unobstructed, enabling the individual to be placed in the boat and removed. We assume that a gear ratio will be needed to allow the user to turn the cranks, and planned to use a chain or belt driven system to alter the ratio. We also need to include some form of seat with backrest that will hold individuals upright that cannot do so without assistance.

    Specifically, we are looking for input regarding what gear ratios to begin testing with, as well as specific paddle shapes that we should investigate further. At the moment, our first choice is to use a "wheel of oars", where oars are mounted on a spindle, rather than what I assume would be a typical steam boat paddle wheel design.

    Thanks for your input, we really appreciate anything the this community can offer!

    [​IMG]
     
  2. portacruise
    Joined: Jun 2009
    Posts: 1,214
    Likes: 73, Points: 48, Legacy Rep: 218
    Location: USA

    portacruise Senior Member

  3. Jeremy Harris
    Joined: Jun 2009
    Posts: 978
    Likes: 59, Points: 28, Legacy Rep: 711
    Location: Salisbury, UK

    Jeremy Harris Senior Member

    Leonardo da Vinci came up with a crank paddle driven boat and I had a go in a replica at Amboise, the place where he died, a few years ago. Despite him being a great inventor he made the paddle diameter too small, with the result that there is a fair bit of frenetic activity for not a lot of forward (or reverse) motion.

    I'd suggest going for the largest practical diameter you can manage, sizing the crank offsets to suit the range of movement available from the paddlers (perhaps consider making the cranks adjustable?).

    In general, moving large diameter paddles slowly is likely to be more efficient in this application than moving small diameter paddles quickly.

    You might also want to consider ways of translating fore and aft motion, for paddlers who are unable to move cranks around. Levers connected to the cranks might make for an easier way for some to make them go around, and would allow for ratio adjustments to suit varying ranges of movement and limb strength. To get around the problem that "treadle" type linkages can have with wanting to start the wrong way, you could look at using something a bit more technical, such as wires wrapped around drums fitted with one way clutch bearings. These have worked OK on propeller driven human powered boats, and offer a neat way of converting fore and aft motion into continuous rotation.

    Hope these ideas are helpful, sounds like an interesting project.
     
  4. Petros
    Joined: Oct 2007
    Posts: 2,936
    Likes: 148, Points: 63, Legacy Rep: 1593
    Location: Arlington, WA-USA

    Petros Senior Member

    paddle wheels are not very efficeint, lot more engrgy expended for the amount of forward movement. you are better off converting the motion to a shaft and drive a propeller. A propeller is a foil or blade that moves in a circle, much more efficient and why you see propellers have completely replaced paddle wheels (except as a nostaliga or replica build).

    A convention paddle actually works by slicing through the water at an angle of attack, kind of like a quarter turn of a propeller. long thin high aspect ratio blades are more efficient, like in the native Greenland kayak paddle blade. One of the difficulties when describing the complecities of fluid mechanic action over a paddle blade is the motion that actually generates thrust is not obvious to the average lay person. If you put a paddle strait down in the water and pull it back it will stall, flutter and not generate a lot of thrust, slice it through the water and you get a smooth motion and lots of thrust. Our muscles automatically adjust the movement to get what feels like the most thrust, the best paddlers do this by instince, others have to be trainned.

    The propeller is the best way to go, which means a more complex means of getting a shaft to rotate on the correct axis for the propeller. this means some kind of gear box or simple drive that turns the motion in the dirction for proper orientation.

    You can also investigate the Hobie fin drive, which has two fins ocillationg back and fourth, but work the way a paddle dose: a foil slicing through the water at an angle of attack to generate forward thrust.

    good luck.
     
  5. Submarine Tom

    Submarine Tom Previous Member

    Not so Petros.

    The data I uncovered years ago when bidding on a paddle wheel drive for a small house boat (not a floathome), revealed similar efficiencies to common propellers.

    The crux of that may lay in the inefficiency of the common propeller.

    While props can be designed to be significantly more efficient than a paddle wheel, few are.
     
  6. philSweet
    Joined: May 2008
    Posts: 2,456
    Likes: 266, Points: 83, Legacy Rep: 1082
    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

    I hope your expectations aren't too high. You can certainly do this as a class project and learn a great deal from it. But as a practical matter, it basically won't work unless the occupant is a trained parathlete. The trouble is with the biometrics. Legs are good at pumping pedals. Arms are not so good. First thing you need to do is to go to a physical therapy center that has arm-and-leg stationary bikes and pedal at 50 watts for ten minutes. Then hand crank at 50 watts for ten minutes. You'll get the idea soon enough. The therapy devices are carefully designed to have a lot of inertia that carries the crank through the dead zones. A lack of this has been a serious problem for pedal boats, including world record holders. On a street bike, the road keeps moving under the wheels so the crank can advance. On the water, it is like going uphill in first on a mountainbike. You tend to stop at the top and bottom of the stroke unless you train not to. Have you spent any time in those pedal-boats in the background? Lie on your belly and try to handcrank those things.

    Realistically, propelling the boat will end up being more of a distraction to occupant than a way of experiencing boating. I worked with the USFS on mitigating the lack of access and experiences for the handicapped for several years (a long time ago). There are a number of outdoor camps that have had this stuff dialed in for twenty years now. But the expertise has very limited distribution.

    If the objective is to study how the disabled recreate, study that. If it is a problem in biomechanics, try to engineer something for yourself. That knowledge is always useful.

    regarding mods and safety-
    - from here, the outfitters guide link- http://www.fs.fed.us/recreation/programs/accessibility/

    I don't mean to be a downer, but normally, such a mod would be designed by an engineer with several degrees, and who is probably disabled themselves. You would learn so much more designing something for yourself. The feedback is instantaneous and viseral.

    Twenty years ago I proposed a power sliding seat to help people row. I've still not seen anybody do that.

    a link to adaptive rowing stuff. - http://www.dezeen.com/2012/08/31/paralympic-design-adaptive-rowing-equipment/
     
  7. Jeremy Harris
    Joined: Jun 2009
    Posts: 978
    Likes: 59, Points: 28, Legacy Rep: 711
    Location: Salisbury, UK

    Jeremy Harris Senior Member

    Notwithstanding some of the caution expressed here (and perhaps a re-read of the OPs post will help - this is a class project, not a production item!), I think there is a lot to be gained from experimenting.

    Paddles are very similar to propellers in terms of overall efficiency. The key to making them efficient is to make the diameter large. Testing has shown, as Tom rightly says, that large diameter paddle wheels can be at least as efficient as propellers, and more efficient than oars.

    Certainly the power available will be limited, but I assume that this is part of the design challenge for this senior year project. You have to make best use of the limited power available. 50 watts is quite enough to propel a small boat at a walking pace, many small sailing dinghies sail quite well on less power than this, as do canoes paddled by children.

    My advice is to go for the lightest, largest diameter, twin paddle set up you can come up with, together with a linkage that will allow you to change the drive ratio when experimenting.

    Finally, have fun while doing it, it may be a school project with an educational purpose but that's no reason it shouldn't be fun to do.
     
  8. DStaal
    Joined: Apr 2012
    Posts: 20
    Likes: 3, Points: 0, Legacy Rep: 33
    Location: East Coast

    DStaal Junior Member

    I know one of the design criteria is to allow someone to be placed between the cranks using outside assistance, but I think it will be worth while to look at a way to join/link the two cranks once the person is in place. It would allow one armed propulsion, and more importantly go a bit towards the inertia problem mentioned above: Each arm can be at a different part of the stroke. (It's also probable that there will be a specific section of the stroke where they are strong, and this would allow you to make better use of that.)

    Of course, they should still be able to be used independently, but I think it's worth looking at.
     
  9. portacruise
    Joined: Jun 2009
    Posts: 1,214
    Likes: 73, Points: 48, Legacy Rep: 218
    Location: USA

    portacruise Senior Member

    I experimented with one of the jet blade units referenced above several years ago. The downsides were difficulty steering, water spray splashing inside, windage, and noise from the paddle slapping. Depending on the disability, there might be difficulty with simultaneous pedalling and steering a dual paddle wheel. The positives were simplicity, good speed with either hand or foot power, portability, low weight, ability to adjust paddle diameter and adapt to just about any craft. Drive ratio could be varied by easily adjusting paddle wheel diameter, to a certain degree, depending on how close the hull design is above the water.

    I agree with Jeremy on having fun, and that useful speeds can be had with low power. My best inflatable one man fishing pontoons can reach nearly 3 knots on electric propeller drive at 30 watts with RC model props. That is good enough to allow exploring/fun on rivers or protected waters. This is with stable twin 6' hulls, even higher speeds should be possible with longer canoe/kayak hulls.

    Porta

     
  10. Submarine Tom

    Submarine Tom Previous Member

    Mahak213,

    Great project.

    So, two clamp on units with some kind of adjustable drive ratio.

    Where to start with ratios...

    Lets give it a 4 foot diameter.

    The cranks, 1 foot diameter.

    That's probably a good place to start right there.

    You may want to consider making the crank arm length adjustable or interchangable.

    I suspect some individuals will want to cycle with their hands simultaniously, others opposed.

    Your design accommodates that.

    Have you Googled this to see what others have tried already?
     
  11. Submarine Tom

    Submarine Tom Previous Member

    There are many challenges in what you are proposing.

    Wouldn't a small set of oars be easier?

    Even if they had no hip mobility and could only use their arms.

    They don't have to row backwards.

    A propeller set-up would be far easier but may not be as removable.

    It could still be simultanious or opposed via an adjustment plate.

    One bonus is it could be single handed and wouldn't be affected by a strength imbalance between arms.
     
  12. paddilack
    Joined: May 2012
    Posts: 10
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Moss,Norway

    paddilack Junior Member

    I have botched together a hand-powered drill 4-1 ratio, with a 17x13 APC long tail configuration, single hand crank. In my kayak this gives me the ability to move sedately around, but is markedly slower than paddeling. I find that i tire after just a few hundred meters in dead calm conditions. Im working on a solution that allows both hands to be used as this would give more comfortable range. comfort speed with a paddle is 6km/h and I can do 3,5 with the single hand crank.
    This obviously works, just not well..
    Plenty of room for experimentation and improvements though.
     
  13. portacruise
    Joined: Jun 2009
    Posts: 1,214
    Likes: 73, Points: 48, Legacy Rep: 218
    Location: USA

    portacruise Senior Member

    Prophish TrekFin drive pics may still be on facebook. This is a foot push/spring return fin drive which also incorporates steering. Not very fast though. There was also the Man-u-motor many years ago which used a huge prop serving as flywheel which was a hand lever/spring return HP troll motor, also not very fast. Both would be usable in calm, protected waters and allow some fun for individuals with disabilities...

    Weed/debris interference and 90 degree box/gears continues to be an issue with prop drives and may be an even greater consideraton to those with disabilities.

    Porta
     
  14. portacruise
    Joined: Jun 2009
    Posts: 1,214
    Likes: 73, Points: 48, Legacy Rep: 218
    Location: USA

    portacruise Senior Member

    Here's a pic of the Man-u-motor: http://www.nbssportfishing.com/vBforum/f25/after-years-looking-11678/

    P.

     

  15. Submarine Tom

    Submarine Tom Previous Member

    Mahak213,

    What happened to your project?
     
Loading...
Similar Threads
  1. fish53
    Replies:
    13
    Views:
    472
  2. misanthropicexplore
    Replies:
    26
    Views:
    2,395
  3. mustafaumu sarac
    Replies:
    4
    Views:
    1,096
  4. vishal
    Replies:
    4
    Views:
    864
  5. Steve Wright
    Replies:
    3
    Views:
    820
  6. Meik
    Replies:
    4
    Views:
    2,082
  7. mustafaumu sarac
    Replies:
    14
    Views:
    1,716
  8. mtumut
    Replies:
    13
    Views:
    1,445
  9. black_sails
    Replies:
    7
    Views:
    1,703
  10. Rurudyne
    Replies:
    6
    Views:
    1,274
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.