Human Powered Boat

Discussion in 'Boat Design' started by SolomonGrundy, Feb 12, 2005.

  1. Toot
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    Toot Senior Member

    Well, if you're intent on using gears anyway, here's another thought.

    Props work more efficiently at low speed than high- that's why these vessels have large props. However, I believe that for maximum output, you want to keep your body operating near the optimal cardiac level (there's a name for that, but I can't remember!)

    So would it perhaps be more advantageous to have a flywheel on the driveshaft? That way while you will encounter variations in pressure against the prop, it won't effect your pedaling so much...

    Taking this thought a step further, even if a flywheel isn't feasible, it might still be to your benefit to use a hollow driveshaft (at least along the portion inside the boat) in order to keep the mass as far out as possible to add greater inertia to the system.

    Maybe even something ridiculous, like a 6" diameter hollow tube might help keep the vessel going when you pause to scratch your nose or whatever.
     
  2. SolomonGrundy
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    SolomonGrundy I'm not crazy...

    efficiency

    I suppose you could review the posts on this thread regarding flywheels, you could look back and take a look at all the posts debating drive options such as bevel gears etc...Ancient Kayaker you could even go to the website of the manufacturer and view his specs. You could take a gander at the pics of the bevel gear that are available on this thread....or you could just read the first page and say the first thing that pops into your head.

    The information posted is sometime far from what I wanted to hear...but still previosuly presented.
     
  3. VladZenin
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    VladZenin Senior Member

  4. Toot
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    Toot Senior Member

    Although I've read the thread in its entirety, it was a few weeks ago. I apologize if some of the finer details of previous aspects of this discussion have slipped my mind. I didn't know I was supposed to be taking notes.
     
  5. frosh
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    frosh Senior Member

    Maybe we have become lost in technicality

    Hi Sol, maybe this search for the holy grail of drive efficiency is just not worth the effort. Another option is to just research all previous HPV's that seemed to work well and emulate that. Then you could spend the time saved by thinking and worrying about the ultimate system on training instead.
     
  6. Toot
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    Toot Senior Member

    I was thinking more about this during a break. Here's where my thoughts led me....

    On a normal boat, a sideways configuration is less-than optimal because there is far more motion in the forward direction, than laterally. Therefore, it is more disorienting to be seated sideways.

    However, if you're talking about a boat that will be travelling at 3mph, this effect becomes less of an issue because you aren't propelling yourself forward at a very significant rate. Therefore, the sea will act upon your vessel (and your body) as it will, without the effects of your meager propulsion.

    Furthermore, since boats are designed to travel forward, they are wont to slip through/over/etc waves in that direction, while being much more suceptible to lateral forces. And, again, in a low-powered boat optimized for attaining (but never achieving) significant velocity in the forward direction, the lateral motion may very well be a greater percentage of the overall motion than the forward propulsion.

    To the experienced experts: Am I offbase here?
     
  7. ancient kayaker
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    ancient kayaker aka Terry Haines

    Re "Ancient Kayaker you could even go to the website of the manufacturer and view his specs ..."

    Ouch. Just trying to help. The guy I was quoting is a qualified gear designer with many years of aerospace and robotic experience so you may want to take his comments seriously. I HAVE read the entire thread and followed your link about the right angle drive but it did not give an efficiency figure. I am leaving on a long trip tomorrow which is why I left the research to you. However I have contacted Berg on your behalf; it will be several weeks before I am able to pass their reply on.
     
  8. SolomonGrundy
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    SolomonGrundy I'm not crazy...

    for anyone who missed it the first time...

    http://www.andantex.com/anglgear.html

    I'm not overly concerned with any efficiency figure on the gear, we only need 50% at the end of the shaft.
     

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  9. frosh
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    frosh Senior Member

    Efficiency losses again!

    Hi Sol, I have checked out the web site for the Angle drive you favour, and if I thought that they might give an accurate substantiated figure for the percentage energy losses I would request the info. from them. I doubt that they have the numbers with proper scientific/engineering proof.
    If you look hard at this, and some other systems, eg Gossamer Aircraft, it seems obvious that this Angle Drive thingo is not aimed at maximum conservation of energy as the rotational forces are converted to new forces acting now at 90 degrees to the input (human effort).
    If you think that just getting 50% efficiency is all that is needed, then that is your prerogative; but it would scare the hell out of me! :eek:
     
  10. SolomonGrundy
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    SolomonGrundy I'm not crazy...

    efficiency vs. practicality

    Which would you install in your experimental vessel? A mechanism with 99% efficiency and an unknown failure rate...or 60% efficiency with a failure rate within designed specifications.

    At the risk of sounding unappreciative, if I had 1/10th as much input into construction financing options as has been put into gear efficiencies, this boat would have been built months ago.

    Understand that the boat will be built as efficient as practical ...it has NEVER been my intent to build a boat that will be as efficient as possible..maybe if someone else had paid for all the design work there would be a different boat but this is hull form and drive system we have spent years working on and that I have paid for.

    Plenty of people have been given the offer to improve upon what we have and since most folks seem to be happy cutting bait, that leaves the fishing to me.
    SG
     
  11. imagery1jw
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    imagery1jw The neophite!

    Has there been any thought to getting a prop made out of graphite? Only reason I ask is you could make it larger for efficiency but lighter than metal. Maybe im out of my element here
     
  12. SolomonGrundy
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    SolomonGrundy I'm not crazy...

    Graphite prop.

    We are currently considering both carbon fiber and aluminum for the prop material.
     
  13. SolomonGrundy
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    SolomonGrundy I'm not crazy...

    Global Challenger Association

    Wow, can you believe it has taken us over 9 months to gain 501(c)(3) nonprofit status for our project... but we did it. We are now able ro recieve tax deductible donations from individuals and corporations. This is a big step for us, as we hope to find fundraising considerably less of a challenge from here on in. There is still a great deal of work ahead and we are still working on getting our website up and running but we are making significant strides forward and we hope to begin construction as soon as adequate funding arises.
    I would like once again to thank those of you who have contributed in one way or another to this project, none of this would be possible without the collaborative effort.

    Jamie Daniel
    Project Director
    Global Challenger Association
     
  14. JEM
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    JEM Senior Member

    is this project still going on?
     

  15. SolomonGrundy
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    SolomonGrundy I'm not crazy...

    ongoing project

    Yes, the project is ongoing. After having all of the materials donated (special thanks to MAS Epoxies & Hartnagles, among others) we are building the boat here in Port Townsend.
    Our site, which is still lacking in the content dept. is: www.hpvglobalchallenger.org
    The forum there is just getting started so if you have an interest in this project join our forum, become a member of the association or just visit & don't forget to click the donation button.
     
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