Pedal Powered Boat for the Baltic Sea / Coastline

Discussion in 'Boat Design' started by KalleA, Apr 30, 2009.

  1. KalleA
    Joined: Mar 2009
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    KalleA Junior Member

    Thanx for the link.

    So, on the typical rowing distance of 2.000 m, Lance would take around 4 minutes. To be compared with Drysdale's single scull world record of 6 min 35 sec, or the M8+ world record of 5 min 20 sec...

    Now, how fast would Lance be in a "traditional" displacement boat, i.e. with no foils?

    Cheers
     
  2. Guest625101138

    Guest625101138 Previous Member

    The 460W would get 6m24s. I expect that over 6 minutes an elite cyclist training for 5 minute output would do significantly better than this power though.

    Rick W
     
  3. KalleA
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    KalleA Junior Member

    Right. In other words, a cyclist would comfortably beat a sculler - even on a hull optimised for sculling, in conditions optimised for sculling (flat water) and on a distance optimal for sculling. On longer distances, and in rougher seas, the cyclist would totally outclass the sculler. Give the cyclist an optimised boat, and the difference becomes even greater.

    I bet you very, very few people know that.

    Cheers

    P.S. With "cyclist" vs. "sculler", I obviously mean pedal/prop vs. the archaic concept of sliding back and forth whilst lifting, turning, lowering and dragging a couple of sticks through the water...
     
    Last edited: May 6, 2009
  4. Guest625101138

    Guest625101138 Previous Member

    I doubt that there are very few people who know a single person pedal boat has hit almost 19kts over 100m. When you think that power in flight mode is roughly square of speed you can appreciate how significant this is over the speed achieved with rowing sculls.

    I have never asked the question but I am betting that when the designers of Decavitator were contemplating 20kts in a human powered boat they did not contamplate oars as the likely means of propulsion. If they did I expect it would have had fleeting consideration.


    Rick W
     
  5. KalleA
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    KalleA Junior Member

    Hydrofoils sound really interesting for lightweight electroboats. What are the drawbacks? What about seakeeping? How does a foiler perform in various weather conditions, compared to a stabilised monohull?

    Cheers
     
  6. Guest625101138

    Guest625101138 Previous Member

    The only boat I flew was V8 with its submerged buoyancy. I have added a foil to V7 but only got partial flight before uncontrollable roll.

    It was like a cushion of air in waves up to about 1ft or so. Would be the same with a foil. Once waves hit the hull it will slow you down.

    A foiler brings in even more complexity than just the propeller. It would be OK on a rowing course. In operation on open water there is the problem of the foils fouling. For a boat weight of 120kg you would need to sustain 250W to make it worthwhile over displacement mode. There is extra drag if you want to operate at reduced effort without flying.

    I looked at it very closely for Greg's record attempt but displacement mode was best at his sustainable power level.

    Rick W
     
  7. KalleA
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    KalleA Junior Member

    I think I will try to summarise what I believe I've learnt sofar:

    1. For wave conditions up to around 0,5 metres, the long-and-narrow stabilised monohull is the most efficient hull approach. Such a boat, optimised for 145 kg displacement and with a 140 - 150 W engine will cruise along at 6 knots.

    2. If one can push out 250 - 300 W continously, the hydrofoil becomes viable, and speeds around 20 knots obtainable. This may be out of reach for the vast majority of pedallers, but easily achieved with a tiny electric motor.

    3. As waves get closer to 1 m and above, a keel will be required for seaworthiness. The added weight and drag from the keel will shave about one knot off the speed with 150 W at the pedals, i.e. 5 knots instead of 6.


    For me, the preliminary conclusion is to begin with a stabilised monohull, the KA77, but with an eye to eventually re-configure it with an added electric motor and retractable foils along the lines of what you outlined in the "Electric foiler" thread. The idea of being able to speed along to one's destination, and then pedal around in, say, the nearest archipelago, is very appealing.

    Cheers
     
  8. Guest625101138

    Guest625101138 Previous Member

    This is a good summary in relation to a single person craft.

    The sea keeping ability of a boat is a function of size. An outrigger stabilised monohull for a larger crew size would be suitable for heavier conditions. With a very large crew with a boat weight getting near 2t you could get a stabilised monohull with ocean going ability.

    Rick W
     
  9. KalleA
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    KalleA Junior Member

    Right, it's of course shown by iLAN boats such as EarthRacer, that stabilised monohulls can be oceangoing.

    So, what's the low-down on outriggers vs. keel, shape vs. gravity?

    - Performance and efficiency. Could one say that, for a given live load, a keel approach will, typically, always be heavier and have more drag than an outrigger solution?

    - Safety. Is one aspect safety and self-righting ability? I.e. that a keel might ultimately be safer, as one can avoid staying upside-down.

    - Comfort. I sort of visualise/imagine that, in rough and choppy seas, the waves could lift the outriggers and rock the boat in ways that might be more uncomfortable than a keel in similar conditions. Is that so?

    Sorry for all the novice questions on basic stuff. I am getting some litterature this weekend to accellerate the learning curve. Any books to recommend?

    Cheers
     
  10. Guest625101138

    Guest625101138 Previous Member

    You can achieve self-righting without a keel providing the pilot is belted in. My V12 achieved this although it did not ever get to the lid stage to completely seal it up:
    http://www.youtube.com/watch?v=PYoW3XjHRbw
    It had no keel. It had swing arm drives so my legs did not need to go very high. My CoG was 380mm above the keel and the KMT was 420mm. So stable once seated but absolutely impossible to board unless someone held it upright until I was seated.

    Greg's first ocean boat also achieved self-righting with only internal ballast. The deck he built was quite high and heavy so it ran the risk of sitting on its side without the ballast. The slide out outriggers allowed him to stand up in it once they were deployed.

    From a pure speed perspective fo a ballasted boat there is some optimum where a deep keel combined with a hull that you sit into is better than an internally ballasted hull. But there are a whole lot of issues with a keel. The overall fastest is the outrigger stabilised monohull but then it is not self-righting.

    The comfort aspect is difficult for me to say. Sea motion does not bother me too much. If I feel secure I am comfortable. I start to feel insecure when bouncing across waves tops at 40kts. That will not happen in a pedal boat. I like the way a deep keel yacht lifts to quartering waves without hardly altering heel. I would not take any of my current pedal boats into open ocean as they do not have the strength to cope with heavy seas and are borderline stable. It would be like taking a racing kayak or rowing scull out there.

    The second sea trial Greg did used a deep keel with enough weight to allow him to stand. I think he preferred this motion but it still made him seasick.

    There are comfort factors but I believe they are somewhat subjective. Plenty of people get seasick on ocean liners at the point they start to feel the swell.

    Rick W
     
  11. KalleA
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    KalleA Junior Member

    From a different thread http://www.boatdesign.net/forums/boat-design/paddle-vs-pedal-26668.html#post265316:
    Do you have any details on your swing arm drive? Like what you used for stroke length, arm length, axle diameter, pull chord geometry, return springs (if any), etc. At first, I felt it would involve too much fabrication work compared to just using a bike crank with pedals, but maybe it's doable. I figure one fabricates a couple of axles that bolt onto the crank, just like the pedals. Then the roller bearings are fixed inside the swing arms and slid onto the axles. A bit or lathe and mill work, but nothing complicated.

    Swing arms interest me for a number of reasons - the lower COG, the lower fairing, the motion as such, and the potential to use the same frame/setup for a FrontRower setup for shallow waters.

    I believe your Faux-Tri concept is self-righting, right?

    Cheers
     
  12. Guest625101138

    Guest625101138 Previous Member

    Look at posts #73 and #75 on this thread:
    http://www.boatdesign.net/forums/boat-design/pedal-powered-boats-23345-5.html

    The wire had mechanical advantage over me. I stroked my feet about 400mm and the chord stroked 600mm. This is not fixed. If desired you can reduce or increase stroke.

    The length shown in Warren's boat were taken from what I determined to be optimum. With a tall person it might be different. At a cadence of 60 and at low power level it is more biomechanically efficient than cycling.

    The swing arm system has a major drawback in that there is no reverse. Until you do not have it it is hard to appreciate the value of reversing (or stopping) on demand.

    The no load tension in the system impacts on efficiency and has a lower limit for the intended speed of stroking. You cannot pull back on the pedals so cleats cannot be used.

    The saving you would make in lower CofG is not worth the trouble for an outrigger stabilised boat.

    The faux-tri is intended to be self-righting. It will rely on having batteries locked down in the central hull to achieve this. The lighter the solar the cells the better as well.

    Rick W
     
  13. spidennis
    Joined: Feb 2007
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    Location: south padre island, texas

    spidennis Chief Sawdust Sweeper

    mirage drive in a foamie kayak

    after googling most of the day, and reading and watching tons, I came across this thread and the links included and have been here quite awhile now!

    I too have plans on using pedal power in a "one off" boat. I want to build something like a sea kayak / surfski cross using the hobiecat mirage drive in a "foamie" design. I haven't found much in the way of photo documentation on building a foamie boats except for here:
    http://www.ptone.com/Kayak/surfboat/building/
    I wish I could find more about this style of building as this i believe is gonna be the best method for me (easy). I watched a bunch of youtube videos about shaping surfboards but a kayak is quite a bit more involved. I was wondering on is there any kind of patterns to be made or used to help shape the hull and deck? I hadn't yet built a boat but for some reason I awoke this morning thinking that this is the time and way about doing this.

    there's the 260 mile Texas water safari race about to start in a few weeks and I'd like to enter it next year. It's mostly a shallow river race with an open bay section at the end. I believe that using both paddle and peddle of the mirage drive, I can exhaust my whole body by the time I got to the finish line.

    there's also the adirondack 90 miler that I'm gonna enter this year but I'll have to paddle it this year, next year will be different!

    so after I look around at various boats on line and come up with a hull and deck design, and i think i can build it, then comes the tough part, building it! any suggestions would be welcome!

    edit:
    one more thing ....
    since I live at the beach, and we have great sand for sandsculptures, and I'm a sandcastle instructor, I figure I'd practice my hull designs 1:1 in sand on the beach. If I did this in my backyard I'd suppose I could use the sand sculptured hull to build a mold and fabricate a boat with that method instead? would that be possible?
     
  14. Guest625101138

    Guest625101138 Previous Member

    The Mirage drive is not very efficient. At best you could expect 50% efficiency. A good prop will get 85% efficiency.

    Using both arms and legs is only advantageous in anearobic operation. For long distance pedalling alone is most efficient and will give the best result.

    The method of glassing over foam is more difficult than flat panel construction and the resulting boat will probably be better using flat panel.

    You can find some interesting reading in this thread:
    http://www.boatdesign.net/forums/boat-design/pedal-powered-boats-23345-20.html

    Rick W
     

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

    spidennis Chief Sawdust Sweeper

    Rick,
    your boats are absolutely fantastic! when I started seeing your boats here I knew I was in the right place!

    with all the talk on props, and the number of boats built with it, I'll have to give that a try, but for a few of my requirements I can see where the mirage drive might have an advantage, for me at least, right now.

    For one, it's already built, no engineering on my part needs to be done. I make the mounting well and install it. No welding, no fabricating (I don't yet do any welding, yet being the operative word!).

    Two, it's shallow draft. very important on the texas water safari, the adirondack 90, and around my local waters where I have to beach a lot. I position the "wings" so that they are flush with the hull bottom and use the paddle, when I have to.

    when a friend first bought his hobie kayak with the mirage drive i though it was a silly toyish contraption until I put my feet to the peddles. I put the paddle down right after that! the same could happen if I got prop drive boat?
    50 vs 85 percent difference?

    rick, that link you provided I got into yesterday and still not thru it! good stuff in there, big time good stuff! You do realize though that my first prop drive boat will be heavily influenced by your designs? they'll be a big, big difference though, your boats look good!

    I can't wait to try out shaping my hull designs in sand. It's really hard to describe hull shape with mere words, but I hope that with a few pics I can show what I got going on.

    I still need specifics on foam, mat and glass though .... possibly some of the local surfers and boat builders might be able to help me out? yeah, I got a few trips to make, time to make a few visits huh?

    50 vs 85 ...... that's haunting me ..... you've built a fair share of boats, along with the others here .... that's got to mean something .... am I already at a turning point? .......
     
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