On Wednesday, November 13, 2013 8:17:22 AM UTC-5, Tom wrote:
The reality is there have indeed been fatalities due to over-strong tow ropes, and one of the preventative measures is to use a rope designed to break in case of over-stress.

The problem is that rope degradation is not recognized and defective ropes are used until they fail prematurely.

Is it a problem that we use tow ropes of a type that is subject to rapid degradation? The structural part of the rope is exposed to abrasion and UV. The open weave of the rope allows grit to penetrate and destroy the rope from the inside out. We use ropes that are dirty and show signs of "acceptable" wear. We test our ropes by towing the next glider.

Rock climbers approach this problem differently. Their ropes are designed to minimize the penetration of grit. The function of the outermost wrapping of the rope is to protect the structural core from grit. When the outermost protective wrapping is worn, the rope is discarded. In the old days, rock climbers would wash their ropes in the washing machine to remove micro grit.

Three questions:
1)Would a simple visual inspection find 99.9% of bad tow ropes before they break (Prematurely)? Do "good" towropes ever break?
2)Are we using the right type of rope?
3)Is there a way to test a tow rope on the ground without destroying it?

If you applied a known load to a tow rope (on the ground) and measured the elongation, would this not give an objective estimation of the condition of the rope? (As fibers break or weaken, the rope will elongate more under a known load). If the elongation is outside the limits, the rope is retired.

Would a magnifying glass improve the visual inspection process?