March 21, 2011
Knot Strength Isn't All About Line Strength
By John Merwin
It’s time for some more notes on knots. Some will recall that I periodically spend absurd amounts of time testing fishing knots on some lab equipment and then publish the results, usually in our print edition. You can read about one such series of tests here.
What then happens is I inevitably get some heat from readers because I didn’t include their favorite knot. Or sometimes my directions are mis-read, with the resulting correspondence claiming that I’m simply off my rocker. So I want to address a couple of misconceptions.
First, I don’t personally care what knot you use to tie on a lure or fly. If you’re comfortable with an improved clinch, say, or a Palomar knot, by all means keep using it. All I’ve done over a period of years is to test and illustrate a variety of knots to give choices for those who might want to experiment or try something new.
One reader took me to the woodshed because the knot-test results obtained by the North American Fishing Club were substantially stronger than the results I presented. It took me a while to figure out what the difference was. It turns out they were not measuring the break strength of the unknotted line first. Instead, they just used the manufacturer’s labelled strength in calculating knot-strength percentages.
The line-strength numbers you see on spool labels are almost invariably wrong. A spool of mono labeled as “10-pound-test,” for example, might contain line that actually breaks (dry) at around 16 pounds. Tie a good improved-clinch with that line, and the knot might break at around 14 or 15 pounds. If you believe the spool label, you just tied a wondrous knot that’s stronger than the line itself!
But that of course isn’t true. In fact, it’s a physical impossibility. If you pull on the line to test a knot, the line will always break at 100% of line strength. It’s impossible to measure the knot at a tension greater than that. The line might break before the knot does--in which case you’ve tied a very good knot--but I can’t say you’ve tied a “120-percent knot” or something similar. (There are exceptions, but they only pertain to knots tied with a doubled line.)
As another case, I once suggested using Palomar knots to attach a small barrel swivel between braided line on the reel and a monofilament or fluorocarbon leader. One reader told me flat out that was impossible because the Palomar on the leader side of the swivel would require passing the entire rod through a knot loop. Phooey. Tie the leader on one side of the swivel first with a Palomar knot. Then tie the braid on the other side, also with a Palomar. Done in that order, it’s an easy connection to make with no awkward passing-through-loop problems.
I often hear--and it’s quite true--that the best fishing knots are those you’re most comfortable in tying and that still seem adequately strong. Hey, if it works for you, stick with it. It is also true that most lab equipment tests knots with a very slow pull, instead of the kind of sudden surge you might get in fighting a big fish.
To test knot-strength under the surge or sudden-impact scenario, I need to build a shock tower. I'm curious about that, too, so it’s in the works. Stay tuned....