Rated line strength isn't necessarily an indication of knot strength

In a recent post the question was asked how big a fish would be required to break six pound line. Surprisingly, the answer is a very small fish under certain circumstances, and very large under others. I answered the post and also used this topic as basis of my tip in the recent Fish Explorer newsletter.  So I thought I might expound a bit further on the realities of line and knot strength in terms of monofilament (and fluorocarbon).

First off, when you purchase a line, say eight pound test, what are you buying?  It’s my understanding that most line strengths are minimums, meaning the line will break at or above the rated strength.  So a line that always breaks at ten pound or better could be sold as ten, eight, six, or less.  I’ve seen a variety of line diameters with the same line strengths and vice versa. Point is, when comparing line strengths, compare the diameters also.  Otherwise, you’re not making relative strength comparisons. 

Note if you decide chase line class records you need to get IGFA rated line. Those lines are manufactured to break at or below the strength listed.  Should you not use such line, the line class will be based on the highest strength the line you used tests out at.  Simply if you bought “normal” off the shelf line and set out to set the four pound line class record for catfish and happened to land your fish, you’d have to submit your line with your application.  If it broke over four pounds you’d be put in the next line class up and it might be good-by record.

Something I’ve always found to be mildly humorous is line strength is based on a knot free line.  Yep, it gets wrapped around “barrels” at both ends and stretched until it breaks.  Not a very realistic test from my viewpoint, as I have never figured out how to fish a line without some sort of connection, most commonly referred to as a knot.  You don’t normally see lines rated for knot strength do you?

Occasionally you’ll see an article rating lines for various properties, including knot strength, but with the constantly changing market place it’s difficult to keep up, and even within a brand manufacturing process get changed.  Further, everyone has different knot preferences and some knots work better than others for specific lines and purposes.  So what’s one to do?

I don’t have a clean answer, but I can share my solution to the problem in terms of my needs.

First off, I use the following knots for most of my fishing, improved clinch, clinch, double surgeon, triple surgeon, Duncan loop, blood knot, and Albright knot.  Second, I fish mostly monofilament leaders, and occasionally fluorocarbon. Third, as I’ve aged I’ve found that my knot tying isn’t as precise as it used to be.  Yep, I’m more prone to tie bad knots than ever.  Frustrating as hell when I make a cast and find my knot failed, even more so when fighting a fish, and my leader blows up on me, especially at the knot.

So what I want most in my leader material is for it to be forgiving of bad knots and retain a high degree of strength when they occur.  As a fly fisher I have a habit of adding knots (wind knots or better called casting knots) while fishing. So no matter how well I tie my knots, I know at some point while fishing I’m going to weaken the system with a few extra half-hitches.  Thus, a line that is a bit forgiving is a plus to me.

An easy way to get a feel a line’s knot holding strength is to throw a half-hitch (wind knot) into the line and pull steady until it breaks.  As half-hitches typically reduce the line strength by 50% or more, this simple technique with quickly expose whether a line can take “bad” knots and retain reasonable strength.  I avoid lines that break easily with a half-hitch and opt for those that hold up better to my bad knot tying practices. And rest assured some super strong lines fail at very low strength when a half-hitch is introduced.

This simple check shouldn’t be the only criteria when purchasing lines or leaders, but failure to give consideration to which knots will work best for your lines, fishing needs, and knot tying skills will cost you dearly as some point.  That is assuming it is important that you land that fish of a “life time”.