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Re: Fwd: ProLimit Releasable Spreader Bar

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  • hungvuatnetcomdotca
    ... pretty ... the force ... way to ... The smoother the strap, the closer you get to 1/2 of the harness line pulling force. Additionally, the momentum of the
    Message 1 of 24 , Feb 26, 2002
      --- In ksurfschool@y..., Mel <kitebord@p...> wrote:
      > Okay, NOW I get it. Thanks for the explanation. It seems like a
      pretty
      > good idea, except for the force required to release it (over half
      the force
      > on whatever's looped to the hook). I wonder if there's some simple
      way to
      > increase the leverage.

      The smoother the strap, the closer you get to 1/2 of the harness
      line pulling force. Additionally, the momentum of the "down and out"
      swing will reduce the required force further.

      > Even if you just let it just dangle it would still allow you to
      hook in.

      True.

      > Maybe better to wrap the strap UNDER the spreader & come out the
      top to
      > grab. I'm thinking you could pull it more easily from that
      position, & it
      > should pull the loop further out of the hook.

      It is easier to grab and pull up that way but I suspect it would make
      it harder for the harness line to release (the force of the harness
      line will create a small ^ on the strap where it can hang on to the
      strap). So a thicker spread bar may be needed to creat a steeper
      strap angle that discourages the harness line to hang on to the small
      ^.

      With the swing down and out method, once you can get the harness line
      clear of the hook, the mission is accomplished; beside, you can also
      make use of the swing down and out momentum to reduce the chance of
      the ^ happens.

      On the other hand, the pull up method can reduce the pulling force to
      1/4 or less by using a leverage system silimar to the mordern sail
      downhaul (the original downhaul was 1/2 of the sail tension which is
      reduced to 1/4 to 1/8 in mordern sail). You would need a strong cross
      bar near the harness hook and another one at the spreader bar to do
      this.

      Hung.
    • Mel
      ... side ... The ... So the snap shackle was snapped directly to the trim loop? I should have also asked if the failure to release was caused by failure of
      Message 2 of 24 , Feb 26, 2002
        <kitesrfer@...> wrote:

        > I understand your original question better now. It was a conventional
        side
        > pivot snapshackle. It was connected to a shackle, don't know what size.
        The
        > shackle was in turn connected to the chicken loop.

        So the snap shackle was "snapped" directly to the trim loop?

        I should have also asked if the failure to release was caused by failure of
        the snap shackle to open, or by failure of the open snap shackle to release
        from what it was "snapped" to.

        In either case, this seems like a good reason to avoid side-pivot snap
        shackles (the tip-pivot models also have a different release mechanism).

        Mel
      • Mel
        ... Makes sense. My idea with the strap under the bar & out the top could also give momentum, if the strap was long enough, but you couldn t pull it all the
        Message 3 of 24 , Feb 26, 2002
          hungvuatnetcomdotca <hungvu@...> wrote:

          > The smoother the strap, the closer you get to 1/2 of the harness
          > line pulling force. Additionally, the momentum of the "down and out"
          > swing will reduce the required force further.
          > With the swing down and out method, once you can get the harness line
          > clear of the hook, the mission is accomplished; beside, you can also
          > make use of the swing down and out momentum to reduce the chance of
          > the ^ happens.

          Makes sense. My idea with the strap under the bar & out the top could also
          give momentum, if the strap was long enough, but you couldn't pull it all
          the way out around the front of the hook like your original idea (I didn't
          get that until reading your latest post).

          Mel
        • cfglazier
          ... snap ... mechanism). Mel I don t understand why do you say that the tip pivot shackles are better than the side pivot snap schackles (assuming each is used
          Message 4 of 24 , Feb 26, 2002
            --- In ksurfschool@y..., Mel <kitebord@p...> wrote:
            > In either case, this seems like a good reason to avoid side-pivot
            snap
            > shackles (the tip-pivot models also have a different release
            mechanism).

            Mel
            I don't understand why do you say that the tip pivot shackles are
            better than the side pivot snap schackles (assuming each is used
            with a metal ring)? Both types look like they should work.

            If anyone is wondering, several schacles types are pictured at:
            http://www.wichard-usa.com/Catalog/HR_Snap_Shackles.htm

            Chris G
          • Mel
            ... If used with a ring of sufficient material diameter AND bend radius, which it seems not everyone is aware of (that s the only real problem with that
            Message 5 of 24 , Feb 26, 2002
              cfglazier <cglazier@...> wrote:

              > Mel
              > I don't understand why do you say that the tip pivot shackles are
              > better than the side pivot snap schackles (assuming each is used
              > with a metal ring)? Both types look like they should work.

              If used with a ring of sufficient material diameter AND bend radius, which
              it seems not everyone is aware of (that's the only real problem with that
              factor). The other thing is that the side pivot models require a pull in a
              specific direction. That's not such an issue with the trigger release (as
              sold by www.NorthShoreInc.com), or the line release (like I use - which can
              be pulled in ANY direction to release).

              Mel
            • kitesrfer@aol.com
              In a message dated 2/27/2002 12:33:58 AM Eastern Standard Time, ... Mel, I agree, the side pivot snap shackles do have distinct shortcomings, particularly
              Message 6 of 24 , Feb 27, 2002
                In a message dated 2/27/2002 12:33:58 AM Eastern Standard Time,
                kitebord@... writes:


                >
                > <kitesrfer@...> wrote:
                >
                > > I understand your original question better now. It was a conventional
                > side
                > > pivot snapshackle. It was connected to a shackle, don't know what size.
                > The
                > > shackle was in turn connected to the chicken loop.
                >
                > So the snap shackle was "snapped" directly to the trim loop?
                >
                > I should have also asked if the failure to release was caused by failure of
                > the snap shackle to open, or by failure of the open snap shackle to release
                > from what it was "snapped" to.
                >
                > In either case, this seems like a good reason to avoid side-pivot snap
                > shackles (the tip-pivot models also have a different release mechanism).
                >
                > Mel

                Mel,

                I agree, the side pivot snap shackles do have distinct shortcomings,
                particularly forces are at their most extreme. Of course this is precisely
                the time when you really need these devices to work as reliably, quickly and
                simply as possible. I think that the majority of kitesurfers that use snap
                shackles use this variety, however. In the incident that I described the
                rider had a shackle between the snap shackle and the trim loop. I am aware
                of at least one other case, although there must be many more, where a rider
                snap shackled directly to the trim or chicken loop and as a result was not
                able to fully release the kite even though the snap shackle had opened.

                There definitely needs to be more effective innovation in safety gear by the
                manufacturers. They have improved kite performance dramatically. Safety
                provisions to cope with the sudden, much great power need to also improve,
                soon.

                Rick Iossi


                [Non-text portions of this message have been removed]
              • Mel
                ... That was my point. Tip-pivots, with line or trigger release aren t perfect, but I think they re at least a little better. ... I think you re right,
                Message 7 of 24 , Feb 27, 2002
                  <kitesrfer@...> wrote:

                  > Mel,
                  >
                  > I agree, the side pivot snap shackles do have distinct shortcomings,

                  That was my point. Tip-pivots, with line or trigger release aren't perfect,
                  but I think they're at least a little better.

                  > I think that the majority of kitesurfers that use snap
                  > shackles use this variety, however.

                  I think you're right, unfortunately.

                  > In the incident that I described the
                  > rider had a shackle between the snap shackle and the trim loop.

                  In other words, the snap shackle was "snapped" to a plain shackle. The size
                  & type (plain or "bow") of that plain shackle is CRITICAL. There are
                  usually several sizes & types of shackle which will fit but still fail to
                  release reliably. That's why I think it's unfortunate that most riders use
                  them, since there are likely a good number who don't realize how critical it
                  is (I didn't either, at first).

                  > I am aware
                  > of at least one other case, although there must be many more, where a
                  rider
                  > snap shackled directly to the trim or chicken loop and as a result was not
                  > able to fully release the kite even though the snap shackle had opened.

                  That's another reason I feel it's unfortunate that most riders use
                  side-pivots, because tip-pivots release MUCH better, even directly from the
                  trim loop (even if it doesn't have a plastic tube!).

                  > There definitely needs to be more effective innovation in safety gear by
                  the
                  > manufacturers.

                  That may become unnecessary if the ProLimit releasable spreader works the
                  way it should.

                  Mel
                • kitesrfer@aol.com
                  Mel, If you had to itemize, from your experience an exact best case configuration of center pivot snap shackle and connections types including sizes, what
                  Message 8 of 24 , Feb 27, 2002
                    Mel,

                    If you had to itemize, from your experience an exact best case configuration
                    of center pivot snap shackle and connections types including sizes, what
                    would they be?

                    Rick Iossi

                    << kitesrfer@...> wrote:

                    > Mel,
                    >
                    > I agree, the side pivot snap shackles do have distinct shortcomings,

                    That was my point. Tip-pivots, with line or trigger release aren't perfect,
                    but I think they're at least a little better.

                    > I think that the majority of kitesurfers that use snap
                    > shackles use this variety, however.

                    I think you're right, unfortunately.

                    > In the incident that I described the
                    > rider had a shackle between the snap shackle and the trim loop.

                    In other words, the snap shackle was "snapped" to a plain shackle. The size
                    & type (plain or "bow") of that plain shackle is CRITICAL. There are
                    usually several sizes & types of shackle which will fit but still fail to
                    release reliably. That's why I think it's unfortunate that most riders use
                    them, since there are likely a good number who don't realize how critical it
                    is (I didn't either, at first).

                    > I am aware
                    > of at least one other case, although there must be many more, where a
                    rider
                    > snap shackled directly to the trim or chicken loop and as a result was not
                    > able to fully release the kite even though the snap shackle had opened.

                    That's another reason I feel it's unfortunate that most riders use
                    side-pivots, because tip-pivots release MUCH better, even directly from the
                    trim loop (even if it doesn't have a plastic tube!).

                    > There definitely needs to be more effective innovation in safety gear by
                    the
                    > manufacturers.

                    That may become unnecessary if the ProLimit releasable spreader works the
                    way it should.

                    Mel >>
                  • kiteboard2000
                    ... configuration ... what ... If I understand your question (let me know if I don t), the answer pretty much illustrates my whole point: Size & type of
                    Message 9 of 24 , Feb 27, 2002
                      --- In ksurfschool@y..., kitesrfer@a... wrote:

                      > Mel,
                      >
                      > If you had to itemize, from your experience an exact best case
                      configuration
                      > of center pivot snap shackle and connections types including sizes,
                      what
                      > would they be?

                      If I understand your question (let me know if I don't), the answer
                      pretty much illustrates my whole point: Size & type of connections
                      really don't matter with a tip-pivot ("center pivot"?*) snap
                      shackle. They will release pretty reliably from just about anything
                      they can be "snapped" into: big ring, small ring, fat ring, thin
                      ring, big line loop, small line loop**, fat line loop**, thin line
                      loop, line in plastic tubing, small fat plain shackle, large thin bow
                      shackle,.... That's one reason why I like them so much. They'd
                      likely even release from the corner of a triangle loop, but I haven't
                      thought to try that combo yet (I don't have the parts handy to try
                      right now).

                      *Does anybody know if there's a real name for what we mean?

                      **Notice my current "minimalist" setup has the tip pivot snapped into
                      a rather small loop in fat line. It has released every time, even
                      when I didn't want it too! (for a while I had the release too easy to
                      pull - better too easy than too hard! - & it popped accidentally a
                      few times, under full power).

                      Mel
                    • callum_downie
                      What shaped and what diameter object do you suggest shackling to mel? Just interested because I am unaware of this. What shape is best used with a side pivot
                      Message 10 of 24 , Feb 27, 2002
                        What shaped and what diameter object do you suggest shackling to mel?
                        Just interested because I am unaware of this.
                        What shape is best used with a side pivot shackle and what is best
                        used with a tip pivot?

                        Cheers
                        Callum

                        --- In ksurfschool@y..., Mel <kitebord@p...> wrote:
                        > <kitesrfer@a...> wrote:
                        >
                        > > Mel,
                        > >
                        > > I agree, the side pivot snap shackles do have distinct
                        shortcomings,
                        >
                        > That was my point. Tip-pivots, with line or trigger release aren't
                        perfect,
                        > but I think they're at least a little better.
                        >
                        > > I think that the majority of kitesurfers that use snap
                        > > shackles use this variety, however.
                        >
                        > I think you're right, unfortunately.
                        >
                        > > In the incident that I described the
                        > > rider had a shackle between the snap shackle and the trim loop.
                        >
                        > In other words, the snap shackle was "snapped" to a plain shackle.
                        The size
                        > & type (plain or "bow") of that plain shackle is CRITICAL. There
                        are
                        > usually several sizes & types of shackle which will fit but still
                        fail to
                        > release reliably. That's why I think it's unfortunate that most
                        riders use
                        > them, since there are likely a good number who don't realize how
                        critical it
                        > is (I didn't either, at first).
                        >
                        > > I am aware
                        > > of at least one other case, although there must be many more,
                        where a
                        > rider
                        > > snap shackled directly to the trim or chicken loop and as a
                        result was not
                        > > able to fully release the kite even though the snap shackle had
                        opened.
                        >
                        > That's another reason I feel it's unfortunate that most riders use
                        > side-pivots, because tip-pivots release MUCH better, even directly
                        from the
                        > trim loop (even if it doesn't have a plastic tube!).
                        >
                        > > There definitely needs to be more effective innovation in safety
                        gear by
                        > the
                        > > manufacturers.
                        >
                        > That may become unnecessary if the ProLimit releasable spreader
                        works the
                        > way it should.
                        >
                        > Mel
                      • Mel
                        ... It s different for every different side pivot snap shackle (the normal type). There s a minimum bend radius required for reliable release, depending on
                        Message 11 of 24 , Feb 28, 2002
                          callum_downie <callum_downie@...> wrote:

                          > What shaped and what diameter object do you suggest shackling to mel?
                          > Just interested because I am unaware of this.

                          It's different for every different side pivot snap shackle (the "normal"
                          type). There's a minimum bend radius required for reliable release,
                          depending on the exact shape & pivot point. I recommend using a tip pivot
                          shackle instead, or at least opening the side pivot shackle & trying to MAKE
                          the object get stuck on the open end. If you can make it stick, there's a
                          chance it will stick when you don't want it to.

                          > What shape is best used with a side pivot shackle and what is best
                          > used with a tip pivot?

                          Side pivot: see above.
                          Tip pivot: see my recent post - anything I've tried will work (check with
                          your own parts before use).

                          Mel
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