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  1. #1
    Senior Member
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    Semi foiling 'fly fin'

    Not the first to publicise the semi-foiling aproach, but perhaps the first to offer for sale ? http://www.frpgear.com/

    Interestingly they say it works best on narrower tailed boards, rather than recent wider designs.
    May aid speed maintenance in gybes?

  2. #2
    Mmmmm.
    30% more lift, 10% less drag.

    Or just choose a floatier board with a conventional fin? Or perhaps use a bigger sail?
    Wouldn't there actually be less drag if you took the foil bit off the fin?


    I guess a proper test, with windspeed logged and GPS action recorded would tell us the truth.


    On the other hand, judging foiling boards in terms of the past is not the way to go. Basically, it's a new sport, currently held back by the need to adapt to existing windsurf kit.

    Time will tell, I guess.
    Last edited by basher; 15th January 2018 at 11:53 PM.
    I have some kit for sale, to make space. Nuevo 86 2014, 490, Nuevo 73 2013 550, Severne Blade 2015 5.0 and 3.7. All VGC or little used. Don't use private message system as I don't get messages via here contact via the weather thread!

  3. #3
    Senior Member
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    They do admit that given 20 knots, a conventional fin is faster. Their idea is that older (now cheap) narrow boards can be given the early planning capability to match newer (more valuable) recent wide tailed designs- just with a new fly fin. I know that I can get my relatively narrow tailed board upwind better semi-foiling. However, my guess is that if the 'fly fin' has enough lift to achieve that, then it will (like my Zeeko foil) lift the board clear as soon as the breeze picks up and/or the course is further off the wind. But a test would indeed be interesting.

  4. #4
    Senior Member Sailrepair's Avatar
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    If the fin had enough lift to start lifting the board something will break.

  5. #5
    Senior Member
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    Innovation is to be encouraged but there was little to convince me in the web site and videos that this design achieves a great deal. The kit being used was indeed narrow long boards.....and pretty old as well by the look of them, so maybe this is aimed at places around the world where that older kit still prevails. Even so a more modern rig, decent fin and a more proactive sailing style looked like they would deliver as much or even more performance improvement, and based on the amount of wind noise in the mic on the first video, a modern wide short board with modern rig would certainly be planing fast in those conditions.

    Despite all of that I feel sure there is scope to experiment more with fin design without going to the extremes of instability and cost inherent in current foil designs.
    Last edited by mikerb; 16th January 2018 at 10:33 PM.

  6. #6
    Senior Member
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    Despite all of that I feel sure there is scope to experiment more with fin design without going to the extremes of instability and cost inherent in current foil designs.

    Couldn't agree more. The lift to drag must be horrendous on the current crop. We need something much simpler and much more efficient before we throw away our big sails.

  7. #7
    Junior Member
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    Jan 2018
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    6
    Mikerb,
    Could you please clarify for a novice in sport? Do you mean that a better board, rig and skill will do with Fly-Fin even better compare to what I see in frpgear.com? Or you mean that fly-fin improves only old board, poor rigs and novice skill like myself? I am asking because on some flyFin videos fold board, poor rig and low skill attached to flyfin wins vs modern board, nice rig and expert skill.
    Richarli,
    I have been in aerospace industry since 1980. I am just trying to understand your reference to the lift/drag ratio. Lift.drag ratio of a hydrofoil is significantly higher compare to a planing board.
    The difference can be 4-10 times depending on the aspect ratio of the foil. It means that with the same lift (weight of the sailor) hydrofoil has 4-10 times less drag if correctly designed. when you say that flyfin has too much of drag do you mean that you see something in it that generates more drag? What that would be? I think the concept of flyfin is to reduce much of drag bu lifting the board up while adding negligible drag from the foil.

    I have slingshot hydrofoi and I can set it so it works just like this flyfin. It pushes me up but not enough to fly. It is actually pleasant experience and I get on planing earlier. But my large foil has th huge mast, fuselage and stybiliser - all the extra drag. I think flyfin remove all these useles parts and becomes more effective in just lifting you up so you can plane sooner.

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