Pedal Powered Boats

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

  1. xj35s
    Joined: Nov 2009
    Posts: 16
    Likes: 1, Points: 3, Legacy Rep: 28
    Location: fulton,NY

    xj35s Junior Member

    Can't thnk you enough, That's sweet.
     
  2. portacruise
    Joined: Jun 2009
    Posts: 1,247
    Likes: 83, Points: 48, Legacy Rep: 218
    Location: USA

    portacruise Senior Member

    Welcome, if you live in Texas you can try one out with advance notice I believe:

    http://www.sunshinepedalboats.com/

    Caveats, I have no connection with the company. At least it will give you some idea of how to build. Pretty cool design has a compartment at the rear which can be opened to clear weed from the props, if needed. Has been used to cross the English channel. Way too heavy and slow for what I like to do, though.

    Porta
     
  3. CDN-CUCV
    Joined: Mar 2010
    Posts: 10
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Vancouver Islander

    CDN-CUCV Junior Member

    I see Greg has been in my backyard doing sea trails again in Ucluelet, B.C.. One day, I'll have to make the effort to get out and see him and his boat.

    http://www.pedaltheocean.com/

    Great thread btw...
     
  4. portacruise
    Joined: Jun 2009
    Posts: 1,247
    Likes: 83, Points: 48, Legacy Rep: 218
    Location: USA

    portacruise Senior Member

    Yes, I notice he's working on the issue of high winds pushing him sideways and resulting loss of control to the point of drift. Another reason I don't like rudders- seem to fail when you need them the most. There may be a simple backup solution that has been overlooked, other than those proposed.

    Porta
     
  5. Guest625101138

    Guest625101138 Previous Member

    Vic
    The boat in the trim he had was unintentionally perfectly balanced. It held perpendicular to the breeze once heeled and he could not get enough steering to get out of that situation.

    When he is light he needs to trim stern down to ensure the boat weather cocks aft to the wind. The issue then becomes one of getting enough speed to do a quick turn through the wind to head up into it if he needs to.

    I have proposed twin rudders angled to the vertical so one will always increase grip at the stern when he heels. Will add a bit more drag but will ensure control in strong wind.
     
  6. Guest625101138

    Guest625101138 Previous Member

    Mike
    Mitrpak have quoted USD357 for the box with tapered squares suitable for cycle cranks. The speed step is 1:2 so requires a prop about 500mm diameter. You might get a bit smaller because you prefer to spin fast.

    This ends up being a neat and economic solution. It avoids the chain or belt and a lot of fiddling to set up.
     
  7. mjboats
    Joined: Mar 2010
    Posts: 8
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Minnesota

    mjboats Junior Member

    Very interesting thread, I have to say that I am consumed by the pedel power, well my wife is and i just have to build em.. I currently just started a sportster boat i found on the internet and things are going good, Its a 12' powerboat that I will convert to pedal, I have designed and machine even a miniture prop to make it look like a i/o, very cool, at a glance people will think there is motor inside.. I will get some picture and post them once things get further along,,,, Interesting facts on threads tho thanks keep up good work
     
  8. creekhound
    Joined: Nov 2009
    Posts: 45
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    Location: aurora,Indiana

    creekhound Help me !!!!

    ?

    I have been told to run a 16x16 apc prop on my pedal cat but dont want to do so do to clearance this might sound dum but would a 8x8 4 blade prop have the same output as a 16x16 2 blade
     
  9. Guest625101138

    Guest625101138 Previous Member

    It will need to be spun a bit more than twice as fast to get the same speed because the pitch is half and the slip will be higher.

    It will be less efficient because it is sweeping a much smaller area.

    The blades will have considerably less strength. The blades on the 8" prop will likely be too flexible to take the thrust. Each blade will have less than 1/8th the strength of the larger prop blades if they have the same foil section.
     
  10. creekhound
    Joined: Nov 2009
    Posts: 45
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    Location: aurora,Indiana

    creekhound Help me !!!!

    Thanks for the info we have talked before i lost your email but i did take your suggestion to do a cat.I am almost done with the cat but know i am at the biggest problem the pedal drive system i really am trying to understand all of this but it just seems to be over my head.We talked about me making my own prop at work but i have yet to try.I just want a boat we a low draft a 16 inch prop even at only a couple of inchs below water would put me drafting 18 to 24 inchs i just cant live with that.I dont need to set any speed records here just cover some water all my fishing is done withen 1 maybe 2 miles of launching.would love to draft no more than a foot and then i can flip drive out of way and pole my self in shollower water.My plan was to spin prop 10 to 1 with my twist chain setup i am working on.
     
  11. Guest625101138

    Guest625101138 Previous Member

    Unless you are going to be covering miles in a few inches of water a draft of 18 to 20" is not particularly restrictive. With a two bladed 16X16 prop it will be about 10" of draft with the blades horizontal without even lifting the shaft. If you have some tilting system you can reduce the prop draft to zero.

    The problem with going to small diameter is that you need to have larger blades than you can get for model aircraft to get the thrust capacity. You might get a 12" aircraft prop that would not break or bend ridiculously.

    I would be interested in any photos you have of the boat so far.

    The Mitrpak box is a couple of months away yet but they are also looking at a 1:3 ratio. This would work OK with the 16" prop although the 16" pitch is a bit low for !:3.

    As Ian notes above he is really happy with his 1:3.3 Involute box. I like mine but it is twice the weight of the Mitrpak and you do not need that capacity unless you are a world class athlete wanting to take on Olympic rowers.

    Both Ian and I can take you through long, tedious stories of development on drive systems. The single box might look expensive but you can spend hundreds of hours working through twisted chain drives to get them reliable.
     
  12. creekhound
    Joined: Nov 2009
    Posts: 45
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: aurora,Indiana

    creekhound Help me !!!!

    I do not have a way to post pics but it is modified from a sail boat at a web site called rebelcat.com.It is 2 8 foot long 12 inch plastic irragation pips flat caps on back and coned on front platform is not don because i do not have the drive figured out yet.This craft will have just under 800 pounds floatation that is the weight it would take to make it naturally bouyant.So the you cut that in halfto 400 puonds of recomended payload.I wiegh 215 boat wieghs 70 pounds+- leaves me with more than enough room for gear and anything elses that i might need for a long weekend.Really i guess this is no more than a big hobiecat just doesnt cost as much!I also dont under stand how a 16 inch prop only drafts 100 inchs of water?
     
  13. creekhound
    Joined: Nov 2009
    Posts: 45
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: aurora,Indiana

    creekhound Help me !!!!

    also i found a 3 way gear box but it is only 1 to 1 how would i make that work?
     
  14. Guest625101138

    Guest625101138 Previous Member

    If you only have cones on one end of the tubes, I expect you will get lowest drag with the cones at the aft end. At the speed you will be doing you will have almost full recover of pressure at the aft end. Hence a cone there will reduce the drag.

    The best would be a cone at both ends but if it is only at one end you should be prepared to reverse the hulls.
     

  15. Guest625101138

    Guest625101138 Previous Member

    When the prop blades are horizontal you only need 10" of water with the prop in its operating position not rotating. If you go to a 4-bladed prop it will need roughly the same to float.

    What It means is that you can push off in water calf deep and then start pedalling one in deeper water.

    I make everything flexible so it all bounces over any obstacles.

    A 1:1 reduction will require a very large pitch prop. and the diameter up around 800mm. Ratios around 4 is about the best. But 2 is tolerable and 3 quite good. For faster boats 5 is OK
     
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