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Releasable stone knot: dowel sizes

Discussion in 'Archives - Yahoo Canyons Group' started by stevefisk1, May 12, 2011.

  1. stevefisk1

    stevefisk1 Guest

    Here are some pictures to illustrate the effects of dowel/pin size on the knot. The dowel takes the place of the biner in blocking the knot.

    A big dowel (vs rope diameter) gives you the choice of dressing the knot in two ways: a flatter knot, as shown below:

    http://tinyurl.com/3bkxm95

    or a "bunny ear" shaped knot: http://tinyurl.com/3q953yn

    The "flat" conformation looks like this when the dowel is pulled: http://tinyurl.com/3dmqla7

    and the "bunny ear" conformation looks like this: http://tinyurl.com/3zskgkt

    This configuration seems problematic, because weighting the rope causes the remainder of the knot to tighten around the dowel loop, making it difficult to undo. The flat shape falls open easily enough without the dowel in place.

    Below are two photos of the knot held together with a thin dowel (after I fully weighted it) : http://tinyurl.com/3f9fzrf

    And screwdriver pulled out: http://tinyurl.com/3qbntdt

    Note that the loops held by the dowel are much smaller and fit easily through the knot. In practice this screwdriver was impossible (for all practical purposes) to remove while the knot held my weight, and took about 10 pounds of pull to remove from a slack rope after the knot had been weighted. A firm yank on the rappel strand was enough to get the unsecured knot to fall open.

    I plan to try this with a 3/8" x 10" aluminum rod as the dowel. Wood would be suicidal, and it'll have about half the kinetic energy a steel rod would have, just in case it hits someone on the way down.

    Steve
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