Foil canoe

Discussion in 'Hydrodynamics and Aerodynamics' started by Kenneth Dodd, Sep 18, 2019.

  1. Tiny Turnip
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    Tiny Turnip Senior Member

    I can't help with sums as such, but I am very aware that the amount of power your 4 paddlers can sustain will be critical; the power needed for lift out is very high for a few seconds; and remains rather high to keep the boat flying. I suspect that, once out of the water, you might be measuring length of flight in a few minutes maximum.
    You may find contact with Rick Willoughby helpful. Sadly he is no longer a member of this forum, but he has considerable experience and knowledge with human powered boats, albeit mostly pedal and propeller driven. He is currently experimenting with foils, to reduce wetted area and offer stability, rather than full flying, as I understand it. He is responsible for the design of a number of significant human powered boats and techniques for reducing drag. He designed Greg Kolodziejzyk's boat for the world 24 hour hpb distance record .

    Rick's Boat Pages - Index http://www.rickwill.bigpondhosting.com/

    RickWilloughby https://www.youtube.com/user/RickWilloughby/videos

    adventuresofgreg.blog http://adventuresofgreg.com/blog/

    You may also find the Yale University hydrofoil sculling project and the Rise hydrofoil 4 person rowing shell of interest. (both on youtube)

    Good luck!
     
    Doug Lord likes this.
  2. CocoonCruisers
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    CocoonCruisers Junior Member

    No, it's often true, just not for your ultra-low-power application, where you are already using a super-efficient hull.
    Cats are usually faster as sailboats because these need righting moment for the sail: the boat gets lighter if you can get rid of the keel, and more powerful because the righting moment of the hull grows with beam. In a beachcat you don't even pay the drag penalty of the twin hulls, cause you'll fly one.
    They are also often more efficient in motoryachts, because going slender allows to stay in a regime with some lift from buoyancy beyond the 'hull speed barrier', without going into the less efficient planing regime, while still providing a spacious platform.

    That does sound like a dilemma you can solve with a super-lean hull + foiling outrigger. What speeds are we talking ?
     
    Last edited: Sep 19, 2019
  3. Kenneth Dodd
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    Kenneth Dodd Junior Member

    Last year in our qualifying run God relive showed we attained 14 miles an hour and held for 23 seconds. That's on the extreme edge. At cruising speed which is our maintain stroke qe cruised at 6.5 to 7 mph. Mind you that was with a 3 person boat. You can add 1 to 1.5 mph to cruising speed with 4 people
     
  4. Kenneth Dodd
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    Kenneth Dodd Junior Member

    Okay. So going off that premis, a typical 4 person canoe is 37 ft. Long. I want to add 3 feet to that. Mainly to put in the bow so I can taper the bow more and present less "push" of a bow wave. Am I assuming correctly that at low speeds, the bow wave is the largest hindrance to speed? If we can cut further in before the bow wave starts to create resistance we should be able to achieve faster speeds. Right?? Also the added length will help bouyancy I'm thinking. Reducing draft
     
  5. fishwics
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    fishwics Quiet member

    Cambridge University Canoe Club built a foiled K1 kayak in the late 1960s. (Tandem foils with outrigged floats for initial stability). It was significantly faster than conventional K1s of the time, and foils were promptly banned!

    Moral: Check, if you want to race, that foils are permitted before you make significant investment!
     
  6. BlueBell
    Joined: May 2017
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    Location: Victoria BC Canada

    BlueBell Ahhhhh...

    "800 pounds or less" all up racing weight with four paddlers in a 40 foot canoe?
    Canoe style paddles presumably?
    15:1 length/beam ratio?
    Retractable hydrofoils would add how much to that "800 pounds or less"?

    If this was an OC4, maybe.
    You need kayak style paddles, not canoe style as they produce ridiculous bounce, detrimental to foiling.
    If the rules are wide open then a narrower hull with an outrigger might get on foil.
    A large, slow turning propeller would help but your going to create more weight.

    I am not optimistic you're going to get this rig, as is, to fly, unfortunately.
     
  7. CocoonCruisers
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    CocoonCruisers Junior Member

    Can't really isolate parts - it is the whole hull that generates the wave system, and any good design will be a compromise between minimization of wetted surface, trying to avoid energy lost in wavemaking, stability, insuring decent motion in a little chop, lightweight yet strong structure ... among others.

    Perhaps you could try to figure out the limits of your design space rather than settling for a careful incremental change. How slender can you go without too much trouble in the trickier parts of the circuit, using an existing sprint canoe of whatever length and number of paddlers ? (Urgh did i just suggest that ? I hope it won't snap under whitewater loads; do wear a lifejacket and be sure to prepare the apologies for the club :) ). Perhaps you'll end up targeting such an extreme slenderness ratio that you end up with a 50 footer and a bit of a wavepiercing bow. And, in case there are doubts about the practicality of a super-slender concept with foiling outrigger (length and beam when trying to avoid the rocks etc), take a huge coastal outrigger into the river (With a classic buoyant outrigger that you'll need anyway: a foil will not work in aerated water. Only thing you could do with a foil is lift the outriggger completely out the water in the calm parts of the circuit, reducing drag while providing even better stability).

    Then with that input you could either consult with a naval architect who knows about performance canoes, or prepare to spend at least a couple months learning what is needed yourself. (Maybe the workload could be divided among team members, one looking more into hydrodynamic optimisation, another into structure calculation, a third trying to spy on the competition and one more experimenting with construction etc). If there's a university nearby it might be worth trying to motivate some prof and a bunch of students - you have a fun challenge to offer there!

    Good luck !
     
    Last edited: Sep 25, 2019
  8. tlouth7
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    tlouth7 Senior Member

    Roughly speaking going longer reduces wave-making drag, but increases skin friction and build weight. There will be some optimum length for a given design speed, all-up weight etc (in a straight line on flat water). Rowing shells are very good at hitting this value because they race in such a predictable way. I would be wary of going longer than the state of the art, why did previous designers settle on 37'?

    I think there could be an opportunity to use foils for stability allowing you to make a very slender, round bilged canoe. You would either have one or two surface piercing foils on outriggers (so it would look superficially like Hydroptere) or adjustable AoA foils sticking out of the hull (as per ship stabilisers). The former would be much easier to build, but probably slightly less efficient.
     
  9. BlueBell
    Joined: May 2017
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    BlueBell Ahhhhh...

    I agree, foil-stabilizers for a more slender hull.
    Adjustable everything.
    I've tried this on a three man, kayak paddle style, skin on frame, sit on top, 17:1 length/beam at the waterline.
    It was tricky to get it set up (lots of roll-overs).
    We ended up with a single pontoon and foil, lifting only the pontoon out of the water at speed (~4-knots).

    Maybe your rig will lift off and fly.
    Perhaps your most critical speed will be lift off.
    This will dictate your foil shape and size, and ultimately top-speed.
    And, all that depends on weight.

    Have we lost the OP?
     
    Last edited: Sep 26, 2019
  10. Kenneth Dodd
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    Kenneth Dodd Junior Member

    You are correct in that single blade canoers create a lot of bounce and sway though we minimize it on our technique . But we dont always use singles. Over half the time we use carbon wing double blades. This produces more speed but also uses more energy so we cant stay on them the entire course
     
  11. Kenneth Dodd
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    Kenneth Dodd Junior Member

    Where you're going with that makes sense. We often use our blade to "skim" the surface of the water for stability in rough areas. A set of small stabilization foils at the bow may provide just enough to go with a more slender hull and help to lean turn the craft in the first 90 miles where it is very twisty. Long boats dont fair well there but they come into their strength the other 200 miles where it's more open water. Would something like a skimmer foil work?
     

  12. Kenneth Dodd
    Joined: Sep 2019
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    Location: Texas

    Kenneth Dodd Junior Member

    Tell me about this single pontoon and foil. Would a fool pontoon at the bow provide stability for a 27 inch hull? Would it need two?
     
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