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October 26, 2001

Making the Connection

Finally, a knot test to end the speculation and superstition fishermen often delay in the selection of knots

So how strong are the knots you tie? Most likely, you don't really know.

After all, unless you have a knot-testing machine, you're probably like me in choosing knots based on what your old man showed you in your youth, what you've read here and there over the years or what you've heard from a friend. At best, you may have heard that this knot or that knot is 95 percent or that a knot is "supposed to be" 98 percent.

And, like me, you often may have wondered how strong your favorite knots really are. I decided to find out, testing them against the line strength to gauge the common wisdom about which knots hold up best. I picked a variety of popular knots and set about to test each with both light and heavy lines.

Since the goal here was testing the knots -- and not my dubious ability to tie them -- I went to the man who, literally, wrote the book. Bob McNally -- past SPORT FISHING contributor and author of the popular reference, Fishermen's Knots, Fishing Rigs, and How to Use Them -- tied each type of knot to be tested five times. He tied each with great care. "If it didn't look right or feel right after I tied it," he says, "I cut it off and tied another."

I then spent a long day at the International Game Fish Association's headquarters at the new World Fishing Center in Dania Beach, Florida, site of the final arbiter in this contest: a state-of-the-art, computerized Instron 5543 line tester. After soaking all knots for two hours or a bit more at room temperature to provide a real-world test, I watched over and over while the line tightened as the Instron's clamps drew slowly apart with the knot between. On the computer monitor, a thin blue line started snaking up at an angle of roughly 45 degrees as the increasing tension tightened and stretched the line until, with a slight pop, something broke and the blue line dropped like a stone plummeting off the top of a cliff. In seconds, the exact breakpoint to the nearest 1/100th came up on screen.

The average of five breaks for each knot offered an idea of its strength, but to put that in a meaningful perspective, I had to determine this strength as a percentage of the line strength. In other words, how much did the knot weaken the line? To find that out, I wet-tested the lines without knots 10 times each.

I also calculated standard deviation for each knot's five breaks. That provides a measure of how consistently the knot breaks. Accordingly, this is shown as a letter at the top of each bar on page 55. Those that earned a "high" consistency rating tended to break at nearly the same strength throughout and could be considered somewhat more reliable; those with a "low" rating broke more unpredictably. This factor should be of relevance mostly with two knots very similar in breaking strength.

Terminal knots were tied to a hook that was attached to a loop of heavy mono around one clamp. For line-to-leader knots, McNally tied the 8-pound leader to 30-pound mono and the 50-pound mono to 80-pound leader.

The Results -- With Some Surprises
What I found in this test had a definite effect in which knots I fish, now. Some old CW (Conventional Wisdom) was reinforced, but other CW proved to be OWT (old wive's tales).

Terminal Knots
Many anglers don't use a double line when tying to a swivel or even directly to a hook, so we tested eight terminal knots using the single main line. Perhaps more striking than the specific numbers is the unexpected difference between the light and heavy line. Many of the same knots that proved pretty strong with light line were noticeably weaker with the much heavier line, so it would pay to keep this in mind when deciding which knot to tie.

For light lines, one of the quickest, easiest and most common of all knots, the basic five-turn clinch or "fishermen's knot," proved the most marginal knot at 63.6 percent. Improve the clinch (run the tag end back through the bottom loop) and that strength jumps to 87 percent. But simply double the tag end before you tie the knot and it becomes 98.7. Notice the same for the uni, which came in like the improved clinch at 87 percent. If you double the tag end and then tie it, you've got a terminal knot close to the breaking strength of the line. Doubling the line before tying either the improved clinch or uni offered a more consistent (reliable) knot, as well.

After this test, when I want to fish a single line tied to a swivel or other terminal gear, you'll find me using the uni tied with a doubled line. I'll have a few more ends to snip away when I'm done tying, but it will be worth the trouble.

If you're fishing a single line with heavy stuff, though, the results vary somewhat. The uni tied using a doubled end came in only fair at 85 percent. On the other hand, the improved clinch with doubled end just about hit 90 percent and would seem the best knot. Note that McNally made only three (vs. five) turns with the heavier, stiffer line.

Double-Line Knots
Many anglers (including me) swear by a double line and always tie one at the business end of their main line. Although IGFA rules permit 15 feet of double line up to and including 20-pound test and as much as 20 feet for heavier lines, many fishermen tie only a couple of feet. Common wisdom suggests that the Bimini twist offers just about 100-percent strength; then, most any decent knot one ties below the Bimini with the doubled end offers at least 100 percent of the single line strength since the doubled end offers so much more knot area.

Believe it. Here, the common wisdom proved right on. The Bimini offered 100 percent for the 8-pound (the line breaking well above the knot) and almost as much (97.3 percent) for the 50-pound. So, the Bimini offers great security under all conditions; trim it well and it becomes pretty unobtrusive.

Most fishermen, however, find the spider hitch quicker and easier to tie for a double line. I'd always heard that the spider's just about as good as the Bimini with light lines but falls short in heavier lines. It turns out to be pretty true, based on these tests. At about 95 percent for 8-pound line and 90 percent for 50-pound, it's a good knot -- but a bit weaker than the Bimini.

Line-to-Leader Knots
Some anglers swear by the swivel; they have no need for these knots. But for a variety of reasons, a lot of fishermen (yes, including this one) use swivels only where absolutely necessary -- typically in line-twist situations that can be prevented with a ball-bearing swivel between main line and leader.

Until this test, I'd been a real fan of the uni to connect light line to leader. It's a snap to tie, and the tag end lies conveniently parallel to line/leader. But at least for tying 8- to 30-pound, it proved by far the weakest option and also the least consistent. The Albright was best, but it can be one of the trickier knots to tie and snug properly. Biggest surprise here: The surgeon's knot, the easiest of all line-to-leader knots to tie and also, without question, the ugliest and least streamlined, proved surprisingly tough at over 92 percent. For a short leader (where the bulky knot needn't be reeled through a small tip-top), it seems a great choice.

Where casting's a factor, the smallest knot of all may be one of the best -- the Yucatan (also widely known as the "no-name" knot). Due to some logistical constraints, I didn't have the chance to test the Yucatan with very light line but did have the chance to test it with 30-pound Ande tournament tied to a heavy mono leader. It registered just about 92 percent of the line's break strength, and that percentage would likely have been a good bit higher with thinner 8-pound line. And no line-to-leader knot offers such a smooth, tiny profile as the Yucatan.

Tying 50-pound to heavy leader produced similar results in terms of the hierarchy of the three knots, with the uni weakest and the Albright strongest. But interestingly, all knots came in close to the same strength -- and none of them proved particularly strong (all under 73 percent), so perhaps when connecting heavy line to heavier leader, a swivel becomes a best bet.

Same-Line Splices
Don't you hate it when you connect with a trophy fish and, well into its initial long run, you discover, halfway down your spool, the blood knot that you'd tied when respooling last month? I've never had a whole lot of faith in the venerable blood knot. These tests confirm that, since the blood knot offered only 80 percent of line strength for 8-pound and even less (68.8 percent) for 50-pound. But they also showed me that my preference -- the uni -- was even worse as a knot to splice line to line, particularly with 8-pound, coming in at a paltry 67.5 percent.

Having seen how much difference doubling the tag end can make in terminal knots, I decided to give the same approach a try with the blood knot to splice two identical lines. The result is pretty astounding, at over 97 percent. The finished knot's a little bulkier than a single-line blood, but not a lot.

Of course, for the most secure same-line splice, which should be at least 100 percent of the line strength, nothing beats tying a double line with a Bimini in each line and then tying a blood or uni or loop-to-loop with the two doubled ends. The downside, besides requiring more time to tie, is that this leaves you with three knots on the spool instead of one.