Effect of Surface Damage on Tensile and Fatigue Properties of Nylon Fishing Line
Worawit Wanchana , Haruyuki Kanehiro and Hiroshi Inada
From the file of 'things you already knew, but needed a research study to prove'. You know the importance of checking your line frequently for nicks and abrasions, but this study quantified the degree to what effect that has on overall line strength (tensile strength). While the authors used very heavy tuna fishing line (monofilament of 150 and 400 lb. test) for this study, the findings should be pretty applicable across a wide range of monofilament line sizes, and if anything, the smaller sizes of line bass and recreational users utilize is probably more a concern relative to nicks due to less 'room for error'.
Here are some of the findings from the paper;
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Tensile tests indicated that the strength of notched nylon monofilaments was rapidly decreased with increasing notch depth, and that between thicker and thinner nylon monofilaments, the decrease in the tensile strength of the heavier line was steeper than that of the thinner line.
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It was shown that nylon monofilament absorbed in total about 5% water (the equilibrium state), and took about 10-14 days to do so. This time period should be much shorter for thinner monofilaments used by anglers, and many studies done by various persons or sites when testing lines have typically used soak times of between 2 to 6 hours.
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The tensile strength for the wet samples of both lines was about 10% lower than for the dry ones. This is a pretty well documented fact with monos.
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The tensile strength of both nylon monofilaments decreased about 30-50% with only a 10% (vs. total diameter) notch depth. This drives home the point that even a tiny nick or gash in your line can severely weaken it's overll strength.
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When comparing between dry and wet tensile strength of the same diameter and notch depth samples, it appeared that the tensile strength of wet notched samples were similar to dry samples.
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In the case of un-marred wet monofilament, the loss in breaking strength occurred after absorbing water due to the weakening of the line from water absorption. For notched wet samples, it appears that the surface damage has a more significant effect on the loss in breaking strength than that of weakening after absorbing water.
So the best advice and line of caution should be to A.) check your line frequently for any nicks or abrsions while fishing, and B.) if you notice or feel anything unusual, you should immediately cut off the bad section and retie on to a fresh section of line. As always, it's better to be safe than sorry. You just never know what your next cast might hook.
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