Quote:
Originally Posted by Cory
The knot also dramatically reduces the working load of the line. There are certain knots that are better than others from this standpoint.
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The rule of thumb I've heard as a sailor is that in typical cordage applications knots will reduce available strength by about 50%.
There are many factors that will affect this result. The linked research on different knots, found that well tied knots of different varieties will reduce strength less than the rule of thumb. The paper didn't mention what the knots were tied to, but my guess is something round. If you attach cordage to a sharp edge, then your resulting system strength is likely to be much less.
http://itrsonline.org/wordpress/wp-c...hards.2004.pdf
Also the cordage used in the above test is quite a bit different than spectra.
Also note that if you redirect the rope's direction with a carabiner, it is going to be under greater strain than it would be in a straight line application.
All in all, sand out sharp edges where your rope is attached or contacts a surface and use rope that is much stronger than what you think is needed.
Dave