Soft shackle question

[allene]

Originally Posted by Stumble

I have been using soft shackles recently, and have really enjoyed the way they work. But I am curious if anyone has tried something other than diamond knots in them? The testing seems to indicate a loss of 75% of the strength at the knot, if this could be increased the allowable system loads would jump dramatically.

Since Brion and I did the testing and found the large strength loss from the diamond knot, I have been giving this some thought. The only other knot I have tried so far is the Admiralty stopper. It slips. Also, it is not clear to me that it is the knot that is causing the weakness.

Stronger knots have less sharp bends in them. While there is a somewhat sharp bend in the diamond knot, there is a very sharp bend in the shackle itself where the line going through the eye of the shackle takes a sharp bend going through the on its way to the knot. This is either where the shackles fail or very close to it and it may very well be that it is the line going through the eye that fails and not the knot itself. Or it may be a combination.

My boat is at the yard now so that is my focus but I do plan to get back to this. It is a question that is of interest.

That said, having a shackle that is stronger than the line it is made of isn't that bad.

Be sure to check out my improved soft shackle design http://L-36.com/soft_shackle_9.php

Allen
L-36.com