Foil canoe

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

  1. Kenneth Dodd
    Joined: Sep 2019
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    Kenneth Dodd Junior Member

    I have a question to pose in hopes that someone much smarter than me can give me some council. I am building a racing canoe and would like to know one, is it feasible to mount hydrofoils onto the canoe and will it lift the boat either partially or completely out of the water, and if so what size and type foil would I need to construct? For reference the hull is 40 ft long and 33 inches at the beam. Total racing weight is 800lbs or slightly less. Carbon fiber construction and a very aggressive bow point. Offset centerline. Cruising speed with 4 paddlers is in the 10mph range but we can sprint the boat at close to 15. Can anyone here give me some ideas on this?
     
  2. Deering
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    Deering Senior Member

    Don’t know that I’m any smarter (or even as smart) than you, but my guess is that unless you entirely lift the hull clear of the water you won’t gain much, and the appendage drag will kill you. 15 mph seems pretty marginal and would demand large foils. Interference between foils and paddles would likely present a challenge, either through direct physical contact or by disrupting laminar flow over the foils. Steering/control would be another challenge.

    However, you could discretely deploy a system like this (eFoil | Foils | Lift Foils https://liftfoils.com/efoil/) and clean up at the races.
     
  3. Kenneth Dodd
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    Kenneth Dodd Junior Member

    Your point is well taken. I had not considered the disruption of flow over the foil by the paddle strokes. Though a nominal or even minimal gain by lifting partial hull out of the water and reducing wetted surface, there by reducing drag, may only gain .5 mph, over the span of 50 hours and 265 miles that could equate to a lot. I was also wondering about the size of the foil with so much weight
     
  4. upchurchmr
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    upchurchmr Senior Member

    Good luck with that.
    Foils are very draggy until you lift off.
    I hope someone can help you.
     
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  5. Kenneth Dodd
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    Kenneth Dodd Junior Member

    I was actually thinking of making them retractable when not in use. The premise was to use them an hour at a time. Then when in cruise mode fold them back over the gunnels. I realize this a really off the wall idea and may not be feasible but that's why I posted the question to people more versed and smarter than I am on the subject. Hopefully someone can lend some input.
     
  6. upchurchmr
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    upchurchmr Senior Member

    What are you doing with this canoe?
    The size and number of people for a 40' canoe is --- unusual!???
     
  7. Deering
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    Location: Juneau, Alaska

    Deering Senior Member

    I don’t think partial lift will offset appendage drag. Unless you can get fully out of the water I suspect the net drag will be higher. There are ‘foil guys’ on this board that can help you assess it quantitatively. A quick search on foils here will lead you to many discussions.

    One other thought - assuming you can achieve ‘lift off’ velocity and rise up on the foils, how will that impact your paddle length if you’re riding a foot higher above the water?
     
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  8. CocoonCruisers
    Joined: Dec 2015
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    CocoonCruisers Junior Member

    I'm no expert but i hang on to the learning curve and started about where you seem to are. Wish i'd been pointed to the following as a starting point, so i'll happily share:

    https://www.boatdesign.net/attachments/csyspaperfeb09-beaver-paper-on-moth-pdf.136024/ for Lift/Drag at sizes comparable to yours
    https://www.amazon.com/Hydrofoils-D...=ray vellinga&qid=1568848547&s=gateway&sr=8-1 for scaling and because it includes a human-powered example (that is actually harder than sail because you have less power per weight)
    NACA 63-412 AIRFOIL (n63412-il) http://airfoiltools.com/airfoil/details?airfoil=n63412-il - a foil section some of the moth folks started from (on airfoiltools, limit the curves to only RE=1 000 000 and ncrit=5, which is still a bit off, but the closest to our kind of application that is available on the site)

    Javafoil or xflr5 to get a feel for how different the L/D of a real-life buildable foil is from the 'infinite aspect ratio' L/D figures of the foil sections.

    and one thing that may be hard to grasp in the middle of all the foiling excitement: You can analyse a lot of things in terms of lift/drag, including the contribution of buoyancy alias hydrostatic lift. The lift/drag ratio of your canoe at rest is infinite, and at down-to earth paddling speeds, it is still much better than anything you can achieve with an actually buildable foil.

    Take the advice about foil drag at speeds below takeoff seriously ! For my first little proto with two moth main foils, that effect sucked to an extend where i struggled to paddle the thing back to shore the day i managed to swamp the outboard :)

    Wishing you all the best !
     
    Last edited: Sep 19, 2019
  9. Kenneth Dodd
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    Kenneth Dodd Junior Member

    I guess I could have explained its use in more detail. My apologies. I do extreme marathon canoe racing. The races range in length and difficulty but the two main races I compete in are the MR 340 and the Texas Water Safari. The latter being the premier race. Its 265 miles long and is know worldwide as the worlds toughest canoe race. When the race started in 1963 the only requirement was that the craft you use to get down river MUST be only human powered. Over the years in an effort for more speed teams built canoes stacking paddlers. First 3 then 4 and finally hitting the limit at 6 person canoes. These builds dont have a technical name. They are know only as Texas Outlaw Canoes. Very fast and extremely tough due to the beating they take during the race. My teammates and I are 3 time finishers of this race with each year we finish closer to the top 10. This year we plan to add one more seat and break the top ten, but if we can make it fast enough, maybe go home with that 4ft. trophy. This foil idea is a part of that plan. My other idea I wanted to explore is to design a mutihull canoe ( catermaran hull) and determine if ther is an increase in in speed that can be obtained as well as added stability.
     
  10. Kenneth Dodd
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    Kenneth Dodd Junior Member

    Thanks for the reply. So the idea to reduce drag of the appendages when not in use is to mount them on the gunnels of the boat. When deployed they would hopefully lift the boat a few inches out of the water which doesn't sound like much, but when total draft of the boat is only 4 to 5 inches max, 3 inches less of wetted surface may be huge. When not in use they would fold back inside the boat out of the water. That's what I'm trying to determine. I know it may be a folly excersise to try to get the craft fully out of the water. What you and others are telling me makes sense in that the foils would need to be so large that the added drag may offset the gains. Even if the gain was 1/4 to 1/2 mph, over distance and time, that could feasibly add up to several hours and 10 to 40 miles. In the group that we have begun to compete in, ten minutes can be 3 positions it's that close. And that's in our shorter races. As fo the paddles, we use double blade wing paddles, somewhat like kayak paddles but made 9f carbon fiber and the blades are more of a wing instead of a paddle head. The reach on these is much better than single blade paddles. The foils would only be used during the times we rotate to those paddles.
     
  11. Kenneth Dodd
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    Kenneth Dodd Junior Member

    I think I know what you're referring to. In portions of low water we call it topping the boat. Where we accelerate to max speed which "lifts" the boat out of the water though nominally. That's not something that can be applied long term as it requires to much effort to sustain. So maybe what I'm hearing is that foils may not be the answer. Boat design is definitely another option. I've toyed with the idea of building a catermaran hull design as well to see if that type of hull could produce more speed. I definitely take all advice. The cost of getting it wrong is very expensive when you consider the cost of materials to build
     
  12. CocoonCruisers
    Joined: Dec 2015
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    CocoonCruisers Junior Member

    Certainly not easy indeed. Now that we know that you're into long distance races i doubt even more that sustaining the necessary effort is realistic. But one thing that foils can do is reduce drag in a seaway - how much energy do you waste in the chop ?

    A cat would have more drag than your ultra-slim monohull canoe for the same weight, and the additional structure will probably make it heavier too.

    If stability can make you faster, i'd ponder an outrigger canoe where the outrigger is lifted out of the water by a tiny foil. (While your main hull is already doing great in terms of lift/drag, the little outrigger hull would normally be less efficient: It will tend to be short, oversized for reserve buoyancy, and probably a bit heavier than what is required for floatation just because it also needs to act as a counterweight.)

    Cost of tinkering: There may be pieces to recycle from the moth folks for a start. They iterate a lot. For lifting an outrigger, you could look into stock rc modelling components like helicopter blades. And perhaps into filament wound windsurf poles or fishing rods as beams.

    BTW, have you seen http://human-powered-hydrofoils.com ?
     
    Last edited: Sep 19, 2019
  13. Kenneth Dodd
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    Kenneth Dodd Junior Member

    Hmmm. Interesting. I was always under the impression that cat hulls were faster than monohull. Guess that shows how much I know. As far as stability, it's a luxury and not necessarily a requirement for speed. Its actually just the opposite. In car racing they say loose is fast. Same applies here. Tippy tends to be faster. Stable means wider hull. It's a tradeoff.
     
  14. Kenneth Dodd
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    Kenneth Dodd Junior Member

    Well there are several sections that are class 1,2,and 3 rapids but those are short in duration. However, the last 7 miles of the safari is in San Antonio bay of the gulf. She is rarely in a good mood. Two years ago we spent 8 hours on the last 7 miles fighting 15 knot headwinds and 4 to 5 foot Whitecaps. It was brutal. Last year we were out there 6 hours but that was because we snapped our rudder off and couldn't steer the boat well
     

  15. Kenneth Dodd
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    Kenneth Dodd Junior Member

    I have seen the Flyak. That was what originally gave me the foil idea. Granted that is on a bow foul and aft foil for one paddler. So I thought, what if two or three foils were deployed. But I'm beginning to see that it may be a foolhardy idea
     
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