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fall at ton sai 22-Jan-2004 At 2:56:22 PM G

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A few comments on the knot issue. I think that the use of terms like weak, strong, loose etc has been a bit ambiguous during the discussion.

In evaluating the tie in suitability of a knot I would suggest that ease of tying and strength (of knot and rope combination) are the most important.

Many people have already added their experiences regarding the ease of tying and verifying bowlines and fig 8's.

Tying a knot in a rope weakens the rope due to stress concentrations (related to the way the stress in the rope is distributed across the cross section). Turning through tight corners is a good example of this. So as a general rule, knots that force the rope around tight corners (e.g. bowline) are likely to reduce the strength of the rope more than those that have less tight turns (e.g. figure 8). However, above a certain strength I am not sure how much difference it makes i.e. the force required to break a rope with a bowline in it will still be very large compared to the 'normal' loads that the rope experiences.

Vaughan, to point out a possible flaw in you cross section theory, the cross sectional area of the rope wont change just because the rope is flatter (assuming that the nylon fibres themsleves down decrease size). The rope going from round to say elliptical will still have a similar c-s area, it will just be distributed differently. The different distribution of area may contribute to stress concentrations however.

In response to a previous post about info on knot strengths, I thing that the RMIT outdoors club has a book on single rope techniques (that may even be the title) which has a chapter of knots. I have done a google sear before and found websites that compare knot strengths, just be careful of trusting webpages without evaluating them.

Gerard