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[ksurf] Re: Going upwind

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  • Hung Vu
    ... Why are the fins on a single fin or a double fins board have to be way at the tail of the board? What are the problems of moving the tail fins more toward
    Message 1 of 24 , Oct 3, 1998
      > But I don't believe a lot to the multiple fin configurations with fins in
      > the middle of the length of the board (one of the reasons is because it is
      > dangerous)
      > Who has some ideas about how going upwind with the board "flat" on the
      > water ?
      >

      Why are the fins on a single fin or a double fins board have to be way
      at the tail of the board? What are the problems of moving the tail fins
      more toward the front of the board (let's say right under or slightly
      before the kitesurfer's back foot)?

      Hung.

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    • Martin Rothwell
      ... On the subject of boards..... In wave ski surfing which I have done for about 15 years we have experimented with many different bottom shapes. I don t know
      Message 2 of 24 , Oct 5, 1998
        Bruno Legaignoux wrote:

        > Who has some ideas about how going upwind with the board "flat" on the
        > water ?

        On the subject of boards..... In wave ski surfing which I have done for about
        15 years we have experimented with many different bottom shapes. I don't know
        if the same theory applies in Kitesurfing but has anyone thought about trying
        a combination of concave bottom shapes and channels. On a wave ski the double
        concave and channels can help to drive the power to the rear of the board
        rather than it escaping from the rails. This helps in down the line
        speed................has anyone tried this?????

        Martin




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      • Gadget
        ... Makes sense. How about centre fin under back foot, side thruster under [or just behind] front foot? -- Gadget [Bude, Cornwall, UK]
        Message 3 of 24 , Oct 5, 1998
          On Sat, 3 Oct 1998, Hung Vu wrote:

          >Why are the fins on a single fin or a double fins board have to be way
          >at the tail of the board? What are the problems of moving the tail fins
          >more toward the front of the board (let's say right under or slightly
          >before the kitesurfer's back foot)?

          Makes sense.
          How about centre fin under back foot, side thruster under [or just
          behind] front foot?
          --
          Gadget [Bude, Cornwall, UK]
          mailto:news01@...
          [Remove NOSPAM to reply]
          http://www.blueNOSPAMwatch.demon.co.uk/index.htm
          [a rather dull homepage, with a few new pics added, but hardly worth the effort]


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        • Cory Roeseler
          Regarding concave and channels: My wife, Terese, rode a slightly customized Connelly Big Easy (waterski) in the 97 Kiteboard World Championships and the 98
          Message 4 of 24 , Oct 5, 1998
            Regarding concave and channels: My wife, Terese, rode a slightly customized
            Connelly Big Easy (waterski) in the '97 Kiteboard World Championships and
            the '98 Kitesurf World Championships. It's very stable and user-friendly
            (good for high wind, extreme sailing), but the complex bottom shape makes it
            pretty slow and inefficient upwind. Now she prefers the Open Ocean designs
            with fairly flat bottom sections.

            Cory


            -----Original Message-----
            From: Martin Rothwell <martin@...>
            To: kitesurf@egroups.com <kitesurf@egroups.com>
            Date: Monday, October 05, 1998 1:48 AM
            Subject: [ksurf] Re: Going upwind


            >
            >
            >Bruno Legaignoux wrote:
            >
            >> Who has some ideas about how going upwind with the board "flat" on the
            >> water ?
            >
            >On the subject of boards..... In wave ski surfing which I have done for
            about
            >15 years we have experimented with many different bottom shapes. I don't
            know
            >if the same theory applies in Kitesurfing but has anyone thought about
            trying
            >a combination of concave bottom shapes and channels. On a wave ski the
            double
            >concave and channels can help to drive the power to the rear of the board
            >rather than it escaping from the rails. This helps in down the line
            >speed................has anyone tried this?????
            >
            >Martin
            >
            >
            >
            >
            >______________________________________________________________________
            >
            >Subscribe, unsubscribe, opt for a daily digest, or start a new e-group
            >at http://www.eGroups.com -- Free Web-based e-mail groups.


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          • Bruno Legaignoux
            ... The main problem is that this fin is out of water most time while planing with your board flat (not while sailing on the rail) With this style of sailing,
            Message 5 of 24 , Oct 5, 1998
              srosso@... wrote:

              > Since the center of effort of the kite will be transmitted through your
              > feet to the board the center of effort will be in between your feet - so
              > you are going to need a fin in between your feet then ! Which means that
              > the fins near the side of the board are in the ideal place..

              The main problem is that this fin is out of water most time while planing
              with your board flat (not while sailing on the rail)
              With this style of sailing, it seems that only back fins work. Obviously, if
              you put your straps at the back of the board, it noses up, even if the board
              is a no nose.

              May be there are other ways like using the downwind rail. I remember some
              race boards with square rails.
              Just an idea. Who tried or will try ?

              Who agrees or not that a "flat" board would be faster and going more upwind
              at low and average speeds ?

              Bruno



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            • Dave Terry
              ... the rail for going upwind. A tiny plane held flat on the water can provide a connection to the surface tension and apparent wind will inscrease with
              Message 6 of 24 , Oct 6, 1998
                Hung Vu wrote:
                >
                > > On a "free sail" system such as a windsurfer, you go upwind by moving
                > > the Center Of Force (COF) on your sail backward behind the Center Of
                > > Resistance (COR) of your fins, keels and board.
                > >
                > > So what do you need to do to go upwind in kitesurfing?
                >
                > Very interesting question.
                > Actually most (or all ?) boards use their rail, of which Center is
                > approximatly under your feet which are approximatly in the middle of the
                > board. The reason is that the COF of your sail is between your feet and
                > you can't put your feet aft as windsurfers do because you haven't the
                > Third Foot that windsurfers have.
                > The problem is that the upwind efficiency of a board using its rail is
                > rather poor at low speed (especially under 20 knots).
                > I'm convinced there is a path to explore where the board uses more its
                > fin(s) than its rail.
                > But I don't believe a lot to the multiple fin configurations with fins in
                > the middle of the length of the board (one of the reasons is because it is
                > dangerous)
                > Who has some ideas about how going upwind with the board "flat" on the
                > water ?
                >
                > Bruno
                >
                >
                >
                >
                > My idea is to escape the confines of
                the rail for going upwind. A tiny plane held flat on the
                water can provide a connection to the surface tension
                and apparent wind will inscrease with speed.When course
                or slalom fins were used to direct the plane upwind, it
                seems you wouldn't need to use the rail. The
                wakeboards go upwind using the rail, but in reality, this
                is a drag system. Using a verical stabalizer and speed is
                considerably more effecient. Does anyone have a
                working or tech knowledge about this? Dave Terry______________________________________________________________________
                >
                > Subscribe, unsubscribe, opt for a daily digest, or start a new e-group
                > at http://www.eGroups.com -- Free Web-based e-mail groups.
                >
                >



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              • Dave Terry
                ... I just put a fin box in my board and flattened the tail..I ll be doing a test on this today and will get back to the group with results. .R&D Dave ... Dave
                Message 7 of 24 , Oct 6, 1998
                  >srosso@... wrote:
                  >
                  >> Since the center of effort of the kite will be transmitted through your
                  >> feet to the board the center of effort will be in between your feet - so
                  >> you are going to need a fin in between your feet then ! Which means that
                  >> the fins near the side of the board are in the ideal place..
                  >
                  >The main problem is that this fin is out of water most time while planing
                  >with your board flat (not while sailing on the rail)
                  >With this style of sailing, it seems that only back fins work. Obviously, if
                  >you put your straps at the back of the board, it noses up, even if the board
                  >is a no nose.
                  >
                  >May be there are other ways like using the downwind rail. I remember some
                  >race boards with square rails.
                  >Just an idea. Who tried or will try ?
                  >
                  >Who agrees or not that a "flat" board would be faster and going more upwind
                  >at low and average speeds ?
                  >
                  >Bruno

                  I just put a fin box in my board and flattened the tail..I'll be doing a
                  test on this today and will get back to the group with results. .R&D Dave
                  >
                  >
                  >
                  >______________________________________________________________________
                  >
                  >Subscribe, unsubscribe, opt for a daily digest, or start a new e-group
                  >at http://www.eGroups.com -- Free Web-based e-mail groups.

                  Dave Terry Productions
                  POB 238
                  Paia, Hi. 96779
                  FAXFONE-
                  808-572-6285
                  aerobike@...


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