Weak Links and Leader Lines

Weak links are one of the most important safety features that can be applied to tow launched flight. There are arguments for and against their use, but the most compelling arguments are for their obvious safety benefit.

A weaklink acts primarily as a safety fuse to prevent overloads from being applied to the towed pilot. Under ideal circumstances, the tow operator could foresee every possible development that could occur and react instantaneously to prevent any type of overload from occurring. The real world doesn't work that way. Lines jam, skip off pulleys, get run over by other vehicles or animals, tension control systems fail, operators and pilots alike make mistakes, and meteorological conditions conspire to occasionally overload the system. A properly designed weaklink will blow out before any excessive forces can be transmitted to the pilot or their glider. One weaklink does not work for all pilots. A weaklink should be sized so that it breaks at 75% of the inflight load. Light pilots need weaklinks that break with a lower force than heavy solo or tandem pilots. Wrapping a shoelace and tying a knot is perhaps better than nothing, but very few pilots actually have any idea at what force their links will break. Tying a weaklink has always been the way most people get by. But when you take some 200 pound test line and tie a knot, at what force does the link break? Different knots, how the knot is tied, and even the length of the line used to tie the knot greatly affect how the link will break.

Sewn Weak Links - To ensure consistent breaking strengths, at TowMeUp.com for our own personal use, we use individually sewn and calibrated weak links. All our links are the exact same size and can be combined together to vary the total force required to break the link. We used to offer them for sale, but the demand far exceeded our ability to produce them economically. We do, however, offer the precut and marked line for those who choose to sew their own. The same precut links also work well when tied using the double grapevine knot, but the accuracy varies by +/- 10% or so of a calibrated value depending on how accurately the knot is tied and cinched together.

We currently stock pre-cut and marked weak link line in 135, 150, 200, 250, 300 and 400 pound breaking strengths.

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Knotted Weak Links - For those wishing to simply tie their own custom length weaklinks, we also have Polyester or Dacron line custom manufactured to our specifications , and we offer it in small spools of 100 feet or 1000 feet lengths.

If you are unsure how to tie your own weaklinks, we have provided a n informational page on how to tie your own weaklinks, as well as a page on how to build your own weak link tester to calibrate their breaking strength.

We stock bulk weak link material on plastic spools in the following strengths:

135 pound test (white with a neon green striker)

150 pound test (white with a blue striker)

200 pound test (white with an olive drab striker)

250 pound test (white with a red striker)

300 pound test (white with a black striker)

400 pound test (white with a red and blue striker)

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Leader Lines are typically short lengths of spectra with sewn eyes on both ends. Typically they are connected between the apex of the drogue chute and the weaklink clip in link. Leader lines serve 2 functions. Primarily they are used to add space between the drogue chute and the pilot. In the event that tow tension is reduced in flight, the drogue chute will inflate. The use of a leader line ensures this happens well in front to the pilot, rather than in the pilots face. We typically use a leader line of lower breaking strength than the towline and use it as a "backup" weaklink for those applications where a pilot elects not to use any type of safety link. Our sewn leader lines are available in 15 foot and 25 foot lengths in the following breaking strengths. 500 Lb, 625 Lb, 750 Lb, 1000 Lb, 1200 Lb, and 1800Lb breaking strengths.

Costs

All strengths of sewn weaklinks cost the same, please specify the quantity and breaking strengths desired.

Packages of 10 pre cut and marked 20" cords to be tied or sewn into weaklinks (any size) sell for $ 2.30

Packages of 60 pre cut and marked 20" cords to be tied or sewn into weaklinks (any size) sell for $ 13.20

Bulk weak link line sells for $12 per 100 foot roll, or $85 per 1000 foot roll (any size)

You may mix and match breaking strengths to meet the quantity pricing structure.

For small or large quantities of line please contact us with your request and a custom price quote.

Leader lines sell for $6.50 - $8.50 depending on size and length. Contact us for pricing, and quantity pricing.