Interesting and informative thread
I just did a two-trial test using 20 lb Trilene Big Game mono knotted to two 1/0 hooks hooked around two pen barrels and then pulled apart until something broke. First trial was an improved clinch knot (my usual knot) vs. a non-slip loop knot (the first I've tied in years, following the instructions from the first hit on Google: flyfishlouisania.com) The improved clinch knot failed at the knot. For the second trial, I used the existing non-slip loop knot and tied the broken end of the line back onto the second hook using a regular clinch knot because I didn't have enough tag end to do an improved clinch. This time the non-slip loop failed at the knot. Not exactly a controlled test with a sufficient number of trials, but I found the results interesting. More testing and results to follow.
Here's a little background info: For more than 30 years I have used the clinch knot or improved clinch knot to attach my line to the fly, swivel, hook or lure, with the only exception being that I would probably use a surgeon's loop to attach the line to a split-ring, punched metal lure or large-diameter hook (similar to a loop-to-loop connection: tie the loop, pass the loop through the split ring/eye, put the lure/hook back through the loop and seat the knot). I generally have good success with the improved clinch knot unless the line is old or abraded. I often use the same fly all day without retying. I usually use 20 lb fluoro in the salt and for carp, and I guarantee that I apply more than 8 lbs of pressure when necessary
. In freshwater I do a lot of fishing with light tackle spinning gear and usually tie the line to a snap swivel (same connection as straight-eye hook) and regularly use the same swivel tied with the same improved clinch knot for multiple trips (3 or 4 or even more
), even with 6 lb test line. Without a doubt, regardless of equipment or type of knot used and excluding instances where the fish bites through the line or nicks/wraps the line on something, most of my line breakages occur while trying to land a fish by grabbing the line. I seldom have the line or knot fail in an open-water situation. Granted, when the line breaks it usually does occur at the knot unless the line was damaged ahead of the knot, but the clinch knot works just fine for me. I also use a blood knot for tippet/leader connections, which is basically two clinch knots against one-another, and those knots seldom fail. When I tie the clinch knot or blood knot, I wrap the tag end around the standing line, rather than twisting the loop to make the wraps. With a clinch knot I snug the knot carefully until it "rolls over" where the knot clinches the tag end (i.e., pull the standing line against the lure/fly until the knot starts to slip and then tightens down again, try it and you'll see what I mean). It's difficult to properly tighten the clinch knot when attaching heavy line to a small-diameter hook/swivel. You sometimes have to push the last wrap back over the line because it tries to go behind the hook eye, and you usually have to push the wraps down the standing line towards the eye as you tighten the knot. I don't worry about making the knot "roll over" with heavy line, especially when the hook or leader is likely to break before the tippet/hook connection.
FWIW, I have done some tests in the past with palomar knots and non-slip loop knots, and while I don't recall the specifics I do know that I decided that the clinch knot was much easier to tie and was just as good for my purposes.