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August 03, 2007

Staying Power

Sport Fishing's Doug Olander tested how 73 different 20-pound lines held their connections. Here are the results.

In a previously released feature evaluating the strength of several types of knots ("At the Breaking Point"), we promised another test that would compare the knot strength of various brands of braid and monofilament for the same knots tied by the same person in the same way.

Well, more than 1,300 individual tests later, here's that test - comparing a double-line knot (the venerable Bimini twist), a line-to-leader knot (the Bristol, a.k.a. Yucatan or no-name) and a knot to tie line directly to a swivel or lure (the palomar). The testing process made for three very long days standing at the big Instron line-testing machine at International Game Fish Association headquarters in Dania Beach, Florida.

In its simplest form, the main question that this test sought to answer was, "How do various lines compare in terms of knot strength?"

Typically, though, nothing's ever simple. The first consideration this raises is which knots to use for comparison.

"Industrial" knot-strength tests rely on a straight overhand ("wind") knot. That makes sense in that it ties up in an instant, plus it's very straightforward and consistently tied (even different people will tie it the same way).

However, I had promised a "real world" knot-strength test based on real fishing knots. No one could tell me if the relative strengths of overhand knots would translate to other (fishing) knots.

And that raises another question that factored into this project. Does "knot strength" carry across all knots? That is, if line A out-tests line B for any specific knot, will A then out-test B for all types of knots? Is its knot strength simply greater? Or are some lines better for some types of knots but not as good for others?

I elected to test three types of knots - double-line, line-to-leader and line-to-swivel. Before testing knots though, I determined (by averaging three tests) the actual breaking strength of each line for reasons explained below.

First and foremost among knots to test, I chose a Bimini twist. Why? It's actually quite easy and fast to tie, it's widely popular, and it's reputed to be one of the strongest knots. Note that I tied the same 12-turn Bimini discovered during last year's knot test. In subsequent testing and actual use, I've found this knot generally stronger than a Bimini with 20 or more turns, whether in braid or mono. See the results of the Bimini Knot Test.

I chose a Bristol knot to connect double line to heavy mono leader. Again, it's a knot both easy and quick to tie but still very effective; there are certainly other knots that will do this job and do it very well. I used seven turns since with some lines, more turns failed to cinch down well over the mono leader. See the results of the Bristol Knot Test.

The final knot tested, the palomar (pulling the doubled end through the loop twice), connects a main line straight to a swivel (which can then be tied to a leader) or directly to a lure or hook. It's long reputed to be one of the strongest knots of this type, particularly with braided line. See the results of the Palomar Knot Test.

For each of 73 lines, I tied and tested five Bimini-twist knots, throwing out the low and high breaks and relying on the remaining three for mean and standard deviation (a measure of how much varation occurred during testing). I repeated that for the Bristol and palomar.

All lines/knots were tested dry. Wet-testing - soaking for two hours in room-temperature water - is significant with monofilament because its molecular orientation changes when wet, and the line loses some small percentage of strength. However, wet-testing simply wasn't feasible for our one-man team. Still, with all lines tested the same way, relative results should be reliable for monofilaments; for braided lines, dry-testing should be the same as wet-testing.

All tests were performed on an Instron 5543, regularly inspected and calibrated for accuracy. I am, again, indebted to the International Game Fish Association, which cleared the slate for its oft-used tester to give me carte blanche for three full days.

I made every effort to obtain every type and brand of line on the market when I began collecting materials for this test in late 2006. A few types of line tested may no longer be available, and to be sure, there will be new lines on the market this year, as there will be every year.

Resuts and Discussion
I translated all knot-strength results into percentages of the strength of the line itself. In other words, all these lines tell you they're 20-pound test. But of course they're not. These "20-pound" lines range (dry) from about 18-pound test to more than 50-pound test. If the knot strength weren't considered as a function of the line strength, an 18-pound line with 100 percent knot strength would appear weaker than a 50-pound line that produced only 50 percent knots.

The three tables show knot strength by line in descending order, and tell much of the story. These results show not only that critical percentage break, but also the range (high and low) of the actual breaks in pounds, as well as the standard deviation.

You'll find further analysis below each table. However, all conclusions here come with caveats aplenty. In particular, it's important to reiterate that different types of knots might well elevate some lines that received low ratings here, and vice versa. Even someone else tying the same knots could produce different results.

Even the way tension is applied could produce much different results. That is, these knots all broke with an even, gradual increase in tension. If it had been feasible to replicate for all knots a sudden "snap" test, again, the charts here might have looked quite different.

The bottom line, I think, is that this test offers a pretty reliable idea of which lines do a good job of holding their knot strength for three types of knots. That's worth considering when choosing your line. At the same time, it's important to keep in mind many factors in addition to knot strength when determining which line is best for your needs, such as: actual break strength; resistance to abrasion; stretch, stiffness and memory (in mono); and just how a line feels to you.

Actual Dry Break Strengths of Lines

Bimini Knot Test Results and Discussion

Bristol Knot Test Results and Discussion

Palomar Knot Test Results and Discussion