Kite Line Breaking Strain

by Robinson
(New York, NY, USA)


Hi Tim my name is Robinson, I live in New York. Hope everything is ok my friend.

My question is how do I find out what is the Strength of my kite, or how do I know what kind of kite line I need for my kite? Is the Strength given by the size of my kite or for the wind?


You have mentioned 2 factors which affect the required line strength - kite size and wind strength. A third factor could be added - kite type. For example, power kites and Sleds pull much harder than Diamonds or Deltas, for the same sail areas and wind speeds.

Assuming you have a flat or bowed single-line kite in mind, the following 'rule of thumb' will be safe in most conditions...

"3 pounds breaking strain for every square foot of sail area"

My 4ft Dowel Rok has roughly 15 square feet of sail, so 45 pound line is required. The nearest strength actually available from shops is 50 pounds, so that's what I use.

When the kite is flying near the bottom of its wind range, you can get by with less than half of that. So in very light air I could get away with flying my Rok on the 20 pound line.

If you are hoisting expensive camera gear, you might want to increase the strength somewhat just for peace of mind!

Finally, if you have a rather large kite, you can always measure the line tension directly with a set of spring scales. Note the maximum gust strength reading, while flying on a line that is reassuringly heavy :-)

You might be surprised at how little the kite is actually pulling, even during gusts. Even so, you need to be very generous with the line strength and multiply the max reading by at least 3 to get a minimum breaking strain figure for the line.

Hope this helps!

Comments for Kite Line Breaking Strain

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Aug 06, 2013
Kite Line Strength - More Info
by: Tony Sangster

In 'Challenging Knots ' author G. Budworth Hermes House publ 1999, 2000 P34... Bulky knots weaken line cordage less, preserving of cordage strength.

Double fisherman's (grinner) knot 65 - 70 %, blood knot 85 - 90 %. Bowline 45 %

The loop knot I use is described there as 95 to 100 % efficient. The Bimini twist knot (p 101)- used in big lines for game fishing - adapts well I find to kitelines - it needs two hands and a foot or two to tie. It looks like a modified noose knot. I use the loop to tie with double lark's head to bridle line and a double lark's knot to tether the line to an anchor on the ground.

Aug 05, 2013
Breaking strain of kitelines - further info
by: Tony Sangster

In "Challenging Knots" by Geoffery Budworth publ Hermes House 1999, 2000 p34 'common bowline' 45% strong. Bulky knots are better. For example 'double fisherman's or grinner' knot preserves 65 to 70% of cordage strength and blood knot 85 to 90%, whilst the bimini twist is claimed by some to be 100% efficient.

Further on the bimini twist... On p101 it is described as a loop knot used for big game fishing. It required both hands and a foot (or two) to help make it and is rather like a modified noose knot.

I have used it as the loop knot to attach with a lark's head to the kite bridle. And another lark's head knot for tethering the kite-line to a kite anchor. I could not find any information on the strength of a lark's head knot but presumably a double lark's head (or prusik knot) may be stronger on the basis of the bulkier the knot the better.

I hope that helps!

Aug 05, 2013
Breaking Strain
by: Tony Sangster

Another factor is the knots used in the flying line - some knots including bowline can reduce the line strength at that point by 40% or more. I try to use a knot which minimizes effect on line strength. I do not have the knot book with me at the moment to be able to give you the name of it. In general I double the breaking strain calculated from area and wind speed to allow for knots.

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