To knot, or not to knot... this is the question

Why are lines sleeved?

There has always been a huge debate in the kiting community on whether to sleeve or not to sleeve. This debate is more relevant in the stunt kite world than in the power kite world...but what use is sleeving anyways and why do it?

First, you need to understand a little bit about the characteristics and make up of the lines. Spectra and Dyneema flying line is actually Ultra-high-molecular-weight polyethylene (UHMWPE or sometimes shortened to UHMW), also known as high-modulus polyethylene (HMPE) or high-performance polyethylene (HPPE). UMPE strands are smaller then the thickness of a hair, and have some very awesome characteristics. Size per size, spectra line is 10 times stronger than steel, has nearly zero stretch, no elasticity, is very soft and pliable, has a natural slickness and floats. When these tiny fibers are woven together to make a rope or line, they become exceptionally strong with each braiding process and still maintain their same awesome characteristics. Although all of these characteristics are pretty awesome, it has one slight downside....because it is based off of a polyethylene (think plastic) it has a very low melting point. Meaning that if you raise the temperature around it, it will melt. Cheap 10lb braided cotton line raking across tightly strung 100# spectra will create enough heat to slice through the spectra line like butter with nearly zero damage to the cotton line. Even tying a knot in the line and pulling it tight will create enough heat to start breaking down the individual fibers, causing the line to eventually break....in a sense, the knot cuts itself in half. It is claimed that you will lose up to 50% of the strength of your line with a knot. Meaning a 500# line will only be able to hold 250# before breaking if it has a knot in it.

So.....how do you tie a knot in the line without loss of strength? Sleeve the delicate spectra line with a strong, higher heat resistant dacron sleeving material. Dacron is different than Spectra in that it has a much higher melting point, does not break down nearly as easy and is not naturally slick. The dacron sleeve is able to hold the knot and decrease the amount of heat transfer to the spectra line, allowing you to knot the line while only losing appx. 5%-10% of the strength. So, a 500# spectra line that has been sleeved and knotted will still maintain around 475# to 450# test instead of the #250 test without the sleeving. The other advantages have already been mentioned above, it is softer, thicker, easier to work with and easier to get undone after it has been pulled tight. The spectra core gives the loop/knot the strength, the dacron sleeving protects the spectra from melting itself in half. Knotting or stitching the sleeving material is personal preference and one is not really noticeably better than the other. Knotting is a little easier to work with, especially if/when you need to re-adjust your lines from time to time. With the knots, you can untie them, adjust as necessary and re-tie. This can be done anywhere, at the park, at the beach or in your front yard and only takes about a half hour to equalize all of your lines. Stitching has the advantage of not having bulky knots that can be snag points. Downside to stitching is that you can't re-adjust your lines unless you sit down and rip the stitching and have a sewing machine handy...or just cut the entire ends off and re-sleeve/sew them once the lines are equalized and pre-marked. The other concern with stitching is that the needle pierces the spectra core which could cause damage or abrasions and pre-mature failure over time. Normally this is not an issue but it could happen.

So, now you have some very useless information to discuss the next time the wind is not blowing.

Hope that helps.....