The Prusik Knot

And Its Kiting Applications

The Prusik knot. Where would kite-fliers be without this great shiftable, lockable knot... A bit of a pain to tie at first, but it makes adjusting a bridle so easy! Pulling the bridle straight unlocks the knot, letting you shift it along the bridle line. Pulling on the lines as pairs as in the last photo causes the knot to fold, locking it in place.

Knot Tying Illustration - The Prusik Knot.
The Prusik Knot - 3
The Prusik Knot - 5
Knot Tying Illustration - The Prusik Knot - 7
Knot Tying Illustration - The Prusik Knot - 2
The Prusik Knot - 4
Knot Tying Illustration - The Prusik Knot - 6

I use the Prusik on horizontal bridle loops to shift the knot left or right across the kite, for trimming purposes. More commonly, it's also used to slide up and down the bridle line of, say, a Diamond kite to adjust the Towing Point fore and aft.

On kites with 4 legged bridles, arranged as an upper and lower loop plus a connecting line, this means 3 shiftable knots. For example, the Dowel Rokkaku and Dopero. At least you only have to tie these knots once.

Although it seemed a little excessive at the time, I took this approach on even my smallest Dopero. A tiny kite with a 30cm (12") wingspan. But it sure paid off, since some fiddling was required to get a decent flight out of it!

More recently, I have also used this knot on the vertical bridle loops of a large Genki. Same deal, tiny adjustments can trim the kite left or right.

Now, if you really want to go overboard with knot-tying...

The book Knots: The Complete Visual Guide has an amazing average review score of 5 stars from 12 reviewers - the last time I looked. If it's a more general knot-tying resource you need, this would definitely be it!

There are other ways, some possibly a little simpler, to obtain a shiftable knot. However, the Prusik has worked so well for me over the years that it's the one I would recommend.

This mountaineering knot was invented in 1931 by Dr. Karl Prusik. With one 's'. At least this web-master has finally got it right. Many others still haven't! Prusik later authored a mountaineering manual, which was the first publication to feature this well-known sliding knot.

Tying a Prusik knot actually becomes fun after a while, funnily enough! Be sure to put a Simple knot into the short end of the line though, since constant use tends to pull line through the knot. The short end gets noticeably shorter than you remember tying it originally. Perhaps this happens during locking and unlocking...

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What's New!

  1. Flight Report:
    Carbon Diamond High Wind Experiment

    Sep 23, 14 01:22 AM

    This day's flying had been anticipated for at least a couple of weeks. A 'drag bucket' added to the tail end of the 2m (7ft) span Carbon and Tyvek Diamond was an attempt to raise the upper limit on the flyable wind speed for the kite. From earlier experiences it seems the unmodified Diamond becomes unstable at around 30 kph.

    The first flight was done with the drag bucket adjusted for fairly minimal effect. As half expected, the kite soon started to fly way over to the left and right. So, the wind speed up there must be at least 30kph! This was down at Brighton Beach, but all thoughts of doing KAP soon evaporated, due to the high wind speed. Not to mention the turbulence coming from some high buildings directly upwind.

    For a second attempt, the Velcro fastener was re-adjusted to considerably open up the intake of the bucket. The bucket being two Tyvek flaps which come together over the tail-most region of the sail. This had an immediate effect. More stability! Unfortunately, the extra drag also helped keep the kite at a lowish line angle in some of the fiercer gusts. Lots of line tension ensued, with a huge amount of distortion apparent in the sail.

    At this rate, something was going to break pretty soon, so I struggled to get the kite down to the sand. After shifting the towing point forward by about 3cm (1") the kite seemed a little more comfortable. When the sail of a Diamond distorts badly, it reduces the amount of effective area below the towing point. This is like shifting the towing point back - adding to the problems of too much wind!

    And then the inevitable happened. The already broken-and-repaired horizontal ferrule gave way and the kite promptly folded up and sank to the sand. But not before I had carefully observed every second of the kite's struggles, trying to learn more about Diamond kite behavior in high winds.

    Just an hour after arriving home, the weather station at the nearby airport was reporting gusts to 50kph! It was less further down the coast, but I suspect the Carbon Diamond felt the brunt of around 40kph for at least a few seconds at a time.

    "Simplest Dowel Kites": A free but very useful kite-making e-book. Make a super-simple Sled, Diamond and Delta - step-by-step with photos. Sign up for the e-book and get an emailed series of messages called "MBK Tips'n'Ideas". If you don't need the e-book, consider signing up anyway... You won't believe the value on offer in that message series!

    Read More

New! Comments

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