Pedal Powered Boat for the Baltic Sea / Coastline

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

  1. KalleA
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    KalleA Junior Member

    Shame. From what I've read, it sounds like a useful and interesting application.

    1. Do you know if the information on the cyberiad site about an upcoming new version 9.01 still is current and correct?

    2. Would it be illegal / improper / impossible to get hold of a copy? I understand it is/was freeware?

    Cheers
     
  2. KalleA
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    KalleA Junior Member

    Having looked at the design, I have a few questions (that probably show that my vehicle building eperience to-date is confined to racing cars):

    1. Is there an "optimal" longitudinal positioning of the outriggers? I've noticed that on your boats, they are normally behind the pilot.

    2. Should the arms that transversely fix the outriggers (akas?) be perfectly stiff, or might there be some advantages from a "suspension"?

    3. From the plans, I get the impression that it could be possible to lower the seat slightly into the deck, like on a surfski. Would such a lowering of the COG be beneficial in any way?

    Cheers
     
  3. Guest625101138

    Guest625101138 Previous Member

    What I provided is intended to be easy to build and perform well. There are a myriad of variations. I was not too careful with the detail of the cockpit set up as I just put it around one of my frames. I expect it is slightly too narrow. It needs to be as wide as the deck. The clearance for pedals also need to be checked.

    I have attached a couple of photos showing different outriggers. I really like the conical ones but they are harder to make than the ones depicted on KA77.

    The only time I have completely capsized pedal boats is when I have been using a single outrigger. This is one of the reasons I like two.

    These boats respond reasonably well to "body english" so in some ways there is an advantage in sitting high. The standard seating position in an OC1 is about 100mm above water level and this is roughly what I achieve. The advantage in sitting low is less windage but then with fairing this would not be so much of an issue. THe KMT is so low that getting a few centimeters lower will not make much difference. You rely on outriggers for static stability and body english in conjunction with the rudder once moving.

    The dipping rudders I have on V11J do not respond well enough for dynamic stability so I rely solely on shifting weight. This is somewhat annoying but I put up with it so I have less drag. On KA77 I have shown a decent size under hull rudder. This will be very powerful and will cost about 5W but essential for a seaway.

    Rick W
     

    Attached Files:

  4. KalleA
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    KalleA Junior Member

    Wonderful looking creations! Guess the yellow "banana boat" is based on a kayak? Finish looks really professional.

    What's the best approach to making the conical outriggers? Laminate and vacuum bag four cones over a male mold, and then bond them together butt-to-butt with a re-inforcing strip? Does one fill them with foam?

    The orange boat looks very intriguing, and promts a few thoughts. As my planned operating conditions seem to possibly place me in the borderline zone between outriggers and keel, I wonder if a keel approach could be combined with submerged bouyancy?

    1. Assume a keel of, say, 30 kgs and 1 m below the waterline. This could result in an empty weight of around 50 kgs, I guess, and a total displacement near 160 kgs.

    2. If the submerged hull were to be 1 m below the waterline, I'm guessing that a cylindrical/torpedo shape might be good (minimizing wetted area)?

    3. The idea would be to place the keel weight on the "inside bottom" of the submerged hull. I.e. a combined submerged hull/keel. Does that make any sense, or would it just be the same as making a less bouyant submerged hull (can't get my mind fully around that)?

    4. No idea what's the right superstructure approach with submerged bouyancy - does one just have a "pod" on/above the waterline, or does one go for, say, an iLAN hull with very low displacement?

    5. For flexible draft, and some practical means of entering and exiting the boat without stabilisers, perhaps the submerged hull could be mounted on a daggerboard-like arm, so that it could be raised to touch the underside of the superstructure/upper hull. Since the top of the upper hull (deck?) would be above the waterline, sealing the leg ought not to be necessary/critical.

    6. As an underwater leg would be in place, could it make sense to mount the prop at the end of the submerged hull, with the angular gearbox inside the hull (disregarding the issues of access) and driven by a chain/sprocket from the crank?

    7. Might the added drag from the "daggerboard/drive leg" and possibly greater displacement be compensated for by less wave drag (or whaterver the correct term is)?

    8. How did that orange creature perform?

    Cheers
     
  5. Guest625101138

    Guest625101138 Previous Member

    Submerged buoyancy does not work unless the majority of the mass is contained within the submerged buoyancy. I have tried it with two examples, V5 and V8. The first one almost drowned me. The second one took 2 hours to work out how to get on it.

    The wave drag on KA77 at 6kts is 3% of the total drag. There is nothing you can do with other designs that will get less than this. You can get zero wave drag but the hull has more wetted surface so viscous drag goes up.

    V7 is a Pahoa OC1 built in Australia. It is built from moulds. The canoe cost AUD3500 and the main hull weighs 16kg. It had a slight modification to allow for the drive frame. The frame weighs 10kg and was built be Greenspeed recumbents. It cost AUD1050. It was my pride and joy but did not work much better than V6. Total boat weight is 28kg. I can build lighter now. V11 design is about 1kph faster for the same power. That is a huge difference when you know that power is a cube function of speed.

    V10, the orange boat, was a dog. It sat flat but under way it had a tendency to nose dive. I could not easily alter the seating position to lift the bow. I think I got it to 13.5kph.

    I re-analysed all the hulls I have used once I got Michlet and it confirmed what I had already learnt about the drag.

    The best option for a keel is to increase the inherent stability of the hull and place a small lead weight as deep as you can realistically go. Also sit within the hull. You could expect to achieve around 5kts with this set up. It is no longer beachable unless the keel can be retracted. This makes it twitchy to board. It ends up being a heavier boat. It really needs a trailer for transport.

    Rick W
     

    Attached Files:

  6. KalleA
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    KalleA Junior Member

    It seems there's almost nothing you haven't considered, and in many cases actually tried and tested. Your generosity and patience in sharing this wealth of knowledge is greatly appreciated.

    I gather you have now pretty much nailed it as far as high performance pedal powered boats are concerned - i.e. that further potential improvements are likely to be small, and found in fine-tuning efficiencies, rather than in conceptual quantum leaps. How will your current project differ from it's predecessor(s), is it mainly in lower weight?

    I understand that KA77 represents pretty much the performance optimum for its intended live load and deployment conditions, and that the main potential for further efficiency/performance gain could be in using a smaller rudder for calmer waters and yours truly losing weight. A couple of final questions:

    1. What sort of performance would be gained from, say, a 15 kg reduction in live load? How far from "optimum" would the hull be in such a case, as designed for a slightly higher displacement?

    2. How does a stronger engine influence optimal hull shape? If memory serves me well, I figure it should be possible for a good cyclist to push out over 300 W for a couple of hours. Not that I have any intention or ability to get back to such levels, but just out of curiosity.

    3. You mentioned that you prefer conical outriggers. What is the reason?

    4. I'm trying to get my mind around Delftship now, in order to be able to play around with a superstructure to fit my dimensions. Would it be possible to get a copy of the .fbm file?

    Cheers
     
  7. KalleA
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    KalleA Junior Member

    Out of curiosity, I looked up the Pahoa:

    [​IMG]

    The Pahoa is 630 cm, so substantially shorter and, I guess, quite a bit heavier than the V11. So, the combination of hull dimensions/shape and displamement meant a 10-ish per cent speed improvement, which would otherwise have required a 30 per cent more powerful engine, is that about right?

    If one wanted to use an existing hull, and convert it to pedal/prop, I would have thought that putting outriggers on a single sculler rowing boat might be the most efficient route. At approx. 8 m loa, 30 cm beam and 14 kg (regulated min weight), how far is such a boat from your optimised hulls?

    Cheers
     
  8. Guest625101138

    Guest625101138 Previous Member

    Reducing weight by 15kg would reduce power requirement by maybe 5W. It is that order.

    If you were designing for a tronger engine the design speed would be higher. The resulting boat is likely to be shorter to reduce wetted surface.

    The conical outriggers wave pierce very nicely. I like this because the outriggers do not upset the attitude of the boat. They may not be the best for rougher conditions. The ones you see on outriggers have elevated bows but then modern OCs only have one outrigger and you cannot afford having it buried.

    The fbm file is attached. Don't worry too much about the drive frame. This was just taken from an existing model. It will give you the proprtions.


    The Pahoa is a nice hull in rough water but mine is not self-draining so it sort of defeats the purpose. I did not want a rough water boat. I could not justify the AUD7000 for a new single scull to the treasurer but it was my preferred hull. The reason I went for the Pahoa was the cooperation of the supplier/builder to make some small changes.

    The scull is not quite as good as an optimised hull for pedal power. An optimised pedal boat with an elite cyclist would outperform an olympic sculler. Sculling does not have the biomechanical efficiency of cycling and the hull speed fluctuates quite a lot during the stroke. The hulls tend to be longer than the ideal pedal boat for the same weight. A lightweight mens would be very close to ideal for you. If you can get one second hand it is a good starting point. You may want to put more buoyancy in the bow. The red and boat in this clip is a women's single scull that was provided free to Pete:
    http://www.youtube.com/watch?v=ckWqIgmVM4Y

    Rick W
     

    Attached Files:

    • KA77.fbm
      KA77.fbm
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  9. KalleA
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    KalleA Junior Member

    A friend of mine, who is a former olympic sculler, pointed out that the body movement constricts lung volume/oxygen uptake, and that you must adjust your breathing to the stroke frequency rather than breathe however might be individually optimal. It seems the pedaller has a number of advantages over the sculler. It would be really interesting to see a direct comparison/race where the only variable was the propulsion system and the engine.

    Cheers
     
  10. Guest625101138

    Guest625101138 Previous Member

    A true comparison would involve both boats and propulsion systems optimised. The hull for the pedallerwould be somewhat shorter because the thrust is steady and speed is constant. The scull should have a sliding rigger as this is better than just a sliding seat.

    Going on what olympic scullers can achieve I expect a sprint cyclist would win quite easily in a pedal boat. Also at these higher power levels foils are feasible with a pedal boat and you would expect that a pedal boat with fairing could outperform a rowing 8 over 2000m. The speed variation for a sculler would not be very good for foils.

    The fastest single person pedal boat has achieved almost 19kts - close to twice the speed of a single sculler.

    Rick W
     
  11. KalleA
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    KalleA Junior Member

    I agree that a true comparison should have each hull optimised for the respective propulsion, and that putting the pedal/prop on a scull hull would impose a relative disadvantage. Still, I guess it would win comfortably, particularly over longer distances. I think that this would perhaps be the most powerful display of the advantages of pedal/prop. Simple for anybody to understand: "put a pedal/prop on a boat and it goes faster..."

    The sliding rigger is obviously superior to the sliding seat, but nobody seems to even realise that they exist. Ever since they were banned from competition in the early 80's, they seem to have disappeared. You don't even see them on the lots of non-regulated boats, where the sliding rigger makes tons of sense.

    My underlying thinking was that pedal/prop (done properly) is a much better option for many forms of leisure/pleasure and performance boats than people in general realise, and that some simple comparisons/races might be the most powerful and effective way to convey that.


    Hydrofoils are cool, and probably the most efficient aproach for a sprint, but they are hardly practical for anything beyond just that - a shortish sprint with a powerful engine - are they? By the way, I just saw some very impressive hydrofoil kayaking on YouTube: "Hydrofoil Kayak Vs K1 Sprint Kayak" http://www.youtube.com/watch?v=U95UReP4mdo

    [​IMG]

    Cheers
     
  12. Guest625101138

    Guest625101138 Previous Member

    I understand the Flyaks top out at around 25kph. Decavitator did 37kph. When you think speed is a function of roughly speed squared for foils you start to realise how superior pedal is.

    With optimising foils you could target about 20kph for long distance operation of one to two hours with a top athlete.

    Greg K has more or less demonstrated the advantage of pedal power over long distance.

    I think it will be a long time before pedal power has any serious recognition. Most people conform to the norm. It also has taken a lot of effort to overcome some of the basic weaknesses compared to paddling. I still take a paddle as a back-up when I go long distances. Kayakers do not vcarry a spare paddle. So reliability remains an issue.

    Rick W
     
  13. KalleA
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    KalleA Junior Member

    So, with a small electric motor and some modest battery capacity (say 1 kWh of Lithium batteries), one could have a really fast little boat with some decent range, and capable of some pretty impressive sprints.

    He has indeed, though 24 h is an insane period. How fast would an optimised non-hydrofoil boat go with 400 W at the pedals? This is what I believe a world class cyclist can sustain for a few hours.

    An issue the size, weight and cost of a paddle...

    Cheers
     
  14. KalleA
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    KalleA Junior Member

    Last edited: May 5, 2009

  15. Guest625101138

    Guest625101138 Previous Member

    There is discussion on electric foiler on this thread:
    http://www.boatdesign.net/forums/boat-design/electric-foiler-foil-assist-25980-3.html
    http://www.boatdesign.net/forums/at...339-electric-foiler-foil-assist-6m_foiler.png

    The best lift to drag you can get on a small foiling boat is around 20. So a boat that weighs 100kg will have a water drag of 50N. Windage will be significant as well - say 10N. So total drag is 60N.

    I understand Lance Armstrong can sustain 460W over 20 minutes. So in a good foiler he would be nudging 8m/s as a sustainable speed and something higher in a shorter sprint over 2000m.

    Rick W
     
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