Stand Up Paddleboard--on foils!

Discussion in 'Boat Design' started by Doug Lord, May 1, 2016.

  1. OzFred
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    OzFred Senior Member

    This seems to be a version of foilboard. They've been around for over 20 years, hardly "revolutionary". They've been used as surfboards since the early 2000s.
     
  2. Deering
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    Deering Senior Member

    He's surfing waves. Not sure if you can ride a wave 10 miles - maybe in Hawaii... The leg pumping appears to be happening when he approaches chop, to skip over it without bottoming out on it (and quickly slowing down and taking a header).

    Or it could all be a fake, a mighty impressive one.
     
  3. CT249
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    CT249 Senior Member

    Cool. The rise of the little SOT and kayak sailing rigs and craft like Hobie Adventure Islands interests me. It would be great to see if we could get some of their users into 'real sailing', but as you say there are some significant barriers.

    It would be interesting to know how many people are buying sailing canoes and kayaks.
     
  4. CT249
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    CT249 Senior Member

    It's hard to see how or why the videos of Kai foiling would be faked. In a decent breeze it's not hard at all to get a SUP surfing on chop at a few knots; even without foils you can easily paddle a longboard windsurfer downwind so fast that the centreboard starts developing significant lift and tries to roll the board over. Given the light weight of SUPs it's easy to see how you could achieve take-off speed.

    But Kai has won the world SUP racing championship, so the fact that he can do it doesn't mean that normal people can do it routinely or practically (as distinct from downwind in breeze in chop). Pro cyclists develop over twice the power of leisure cyclists and untrained people. The pros also develop about 30% more power than a Cat 3 racing cyclist; that's the sort of keen local racer who tears the legs off the cafe heroes. Using cyclists as a guide, at a wild guess even the SUP racers I know could be developing only half the power of Kai and leisure SUPpers will be developing even less - so how will that affect their ability to get up on the foils unless they have a big wave and a howling tailwind?

    It's cool to see this, though, particularly since if there's interest it could lead to some foils being available for longboard windsurfing and that would suit me. But the fact that a world champ can do something doesn't mean that a normal person can do it. From some angles, a vid like this can be the equivalent of putting up a video of Chris Froome and Alberto Contador riding up Alpe d' Huez at 21 kmh - sure it's possible, but not necessarily for mere mortals. And of course given the terrible upwind performance of SUPs in a breeze, you could only really do downwinders once the breeze is as strong as it is in these vids. The logistics involved in foiling a SUP seem to be dramatically lower than foiling on a boat, though, so it could be a good way to get a foiling fix for those who want it.
     
  5. projetdared
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    projetdared Junior Member

  6. Skyak
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    Skyak Senior Member

    Sails for kayaks and canoes tend to be rather expensive, or extremely crude. The expensive ones are aimed at the the 17ft touring kayak -more toward assisted paddling than 'sailboat'. This is a weak product in my view because the price is the same as a capable starter sailboat. By number of hulls, 10 to 12ft kayaks outsell 17s by a multiple and they have the stability to sail at hull speed with confidence. The performance prediction/handicap is very similar to keel boats. I think it is a winning product and would be the perfect entry level sailboat the sport desperately needs -but obviously the margins won't be as good.

    The hobbie AI has the utility I want to bring to a lower price. For $5k it is fun in about any weather -that is the selling point vs similar priced sailboats. The AI is super durable -you could hang it up and swing a bat at it like a pinata. Using legs for propulsion is another big plus. The downside is that it is too heavy.

    The way I look at 'real sailing' is that it has the formality, the rules, the history, and the 'baggage'. It will be the natural progression for a percentage of people that learn to sail anything. The biggest mistake the sport is making is NOT having an excellent entry level product. The clubs have the realestate and the organization. If I succeed in establishing an entry paddle/sail class, it would be in everyone's interest to spend one day each year visiting the local club -sail kayaks in the morning, lunch, then mix the crews for races in the afternoon. The people will figure where they belong. You could check to see if the AIs have a local club and invite them to your club. Another big interaction would be using sailing to teach and promote STEM. Sailing towers over all sports and almost all activities for hands on learning motivated by real world environment.
     
  7. Skyak
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    Skyak Senior Member

    I concluded a few pages ago that this is enhanced surfing ability, not real human powered foiling the marketing would imply.

    What I am still looking for is the parameters -what kind of wave does it need? How common is that condition? What angles can it achieve? We need the equivalent of sailing polars.

    The most useful outcome I see is that SUP has the volume to push foil prices down, which can feed back to sail powered foiling.
     
  8. David Cooper
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    David Cooper Senior Member

    There's certainly no evidence of any need for high wattage of input from the human - a few little bounces like that could be done by anyone without getting out of breath.
     
  9. daiquiri
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    daiquiri Engineering and Design

    Aaah, here it is - pure upwind leg-pumping foiling: https://youtu.be/px88XsARHwc?t=1m8s

    Case proven. :)
     

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    Last edited: Oct 24, 2016
  10. Doug Lord
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    Doug Lord Flight Ready

    Sup-f!

    Very cool, Slavi!
     
  11. SVLB
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    SVLB Junior Member

    I will say it is ALOT harder than it looks! after a couple of minutes of paddling your ring out, trying to steer the board in the chop and leg pumping like crazy you can see why you need to be mr. intergalactic sup champion to do it

    We are almost achieving man powered flight, a lower aspect main foil and we will be there i think
     

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  12. Doug Lord
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    Doug Lord Flight Ready

    tubercles

    Very interesting foils. Can you say a little about the theory? The tubercles I've seen looked to me like they were on the leading edge but these look like they're on the trailing edge?
     
  13. SVLB
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    SVLB Junior Member

    The unfinished foil in the front is based on the humpback whale fluke with the leading edge tubercles.

    The black foil I tried a flexible trailing edge but that didnt seem to work (we were still learning to fly a 13' sup so of course it was all the foils fault) thus i took to it with a file and thats how it ended up, it gets a slight flutter on before stalling but that is a good stall alarm in my opinion.

    The fin/mast/whatever has a serrated trailing edge, the light makes it look a bit funny. this and a few bumps from sanding into the kevlar mean the smooth flow is often tripped making the board uncontrollable until the flow reattaches.

    I didnt know how any of this was going to turn out I just figured I've never seen a straight trailing edge in nature so theres gotta be something to it
     

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  14. Tiny Turnip
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    Tiny Turnip Senior Member

    Very interesting.

    Just for clarity, it is humpback whale fins which have the leading edge tubercles. The flukes have trailing edge serrations. My understanding is that the tubercles on the leading edge channel the fluid into faster moving jets, and this gives greater lift. The trailing edge serrations (which are much more common in nature than the leading edge tubercles) I believe control/reduce/stabilise noisy/turbulent flow off the trailing edge.
     

  15. Doug Lord
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    Doug Lord Flight Ready

    tubercles

    ===================
    Thanks for the info! Seems like some interesting experiments-good luck!
     
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