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August 07, 2006

At the Breaking Point

We test 31 superbraids and 27 knots/variations for some surprising results- and a major discovery

Hey, I wasn't born yesterday. I knew very well that superbraid (gelspun polyethylene) fishing lines overtest considerably. So when I caught a trahira - a brown, toothy prehistoric-looking predator - in Brazil a few years ago on 6-pound braid, I figured the line would overtest and put me into the International Game Fish Association's 8-pound line-class category, where the weight of my fish would qualify it as a new line-class world record.


The "6-pound" line overtested, all right: The IGFA's tests not only put it beyond the 6- and 8-pound classes, but also made it too heavy to qualify even in the 20-pound category. Its 23-pound actual breaking strength bumped up  my catch into the 30-pound line class, where it didn't qualify.

That was a rude awakening to just how strong for their size these remarkable microfiber lines can be.

Suffice it to say that anyone intent on world records puts himself at a disadvantage by using braided line rather than monofilament. The reason goes to the heart of two key concepts that serious fishermen using braid need to understand.

1. Braid overtests. Nearly always it proves to be much stronger than the rating stated on the spool - sometimes (per the example above) two or three times what it claims to be.

2. Braid loses strength at the knot. How much has long been debated, but the industry has often cited 25-percent loss of strength at the knot as a fairly typical figure.

This seems to be the basis for line manufacturers understating their braids' break point. As many in the industry have explained to me, they want to provide a cushion that compensates for weaker knot strength.

Braid manufacturers have done so and then some. For instance, the "6-pound" braid cited above broke at 23 pounds. Even if I had in fact lost 25 percent of its strength at the knot, I was still fishing nearly 18-pound-test line!

The issue here really is not fishing for world records. For most of us most of the time, tackle selection is not dictated by plans to break records. What's at stake is understanding your gear and using it to best advantage.

Toward that end, I spent three days testing lines and knots on the Instron 5543 line tester at the IGFA's headquarters in Dania Beach, Florida. My goals were twofold. First, I wanted to find out by just how much various brands of gelspun poly line would overtest. Are any actually rated accurately? How much do actual break strengths vary within a line class? Secondly, I wanted to better understand how a few common and readily tied knots held up with this notoriously slippery line. Which are strongest and most consistent? Which, if any, provide strength better than that 75-percent figure?

Going for Broke
I set out to determine the actual breaking strength of 31 different lines in two popular line classes, 20- and 50-pound. One braid tested, Platypus, is not readily available in the States, but it has long been a well-regarded mainstay of the Australian market and was included out of curiosity.

Each line was tested at least five times. Though the Instron tester provides a graphic readout showing the percentage each line stretches before breaking, I have not included that information. The controlled stretch manufactured into monofilaments varies from about 15 to 30 percent. (So for example, a 100-foot piece of mono will stretch to 115 to 130 feet before breaking.) But with braids, stretch is minimal and varies little, being no more than a few percent.

 Comprehensive Test Results >>

At the Breaking Point / Going for Broke / Braid Knots / Results / Conclusions