Kite Line Breaking Strain
(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!