Hollow Spectra V: Mainline Loops (End Loops, Biminis, Surgeon's)

[pametfisher]

As I said a couple posts ago, I'm new here on Sportfisherman. This is the fifth in a series I'm posting, I will try and add the others as time permits.

If you are going to use a Wind-On leader with your Spinning reel, one of the choices you face is how to make the loop on your mainline for the loop-to-loop connection between it and the Wind-On leader. (Loop-to-Loop photo below.) The loop-to-loop connection lets you change leaders reliably and quickly, in 6' seas, a 20 knot wind, when the temperature is 50 degrees, at night. And if you have pre-tied swivels/split rings to your spare leaders, there are no knots to be tied when the bite is on.

The mainline loop is a critical part of a loop to loop connection system. Done correctly, the mainline loop is a line-doubler. A well chosen line-doubler reduces the tension of the in the loop by half, with no loss of strength (e.g. if the mainline tension is 40 lbs., the tension in the line inside the loop, is only 20 lbs--almost magic).

Halving the tension in the loops is key to the loop-to-loop connection because the loop-to-loop knot itself is a 60-65% knot. Simple math (and real world testing and experience) says that a 60% efficient knot, running at half of the tension of the mainline, is a 120% connection. Of course 120% is meaningless but it does guarantee you a 100% strong connection--no loss of line strength in the connection. (Note: A single loop-to-loop connection is all that is needed.)

For spinning reels, the ideal mainline loop is:
--thin and without knots so that it does not catch loops of line on the spool, leading to wind-knots;
--sized small so that it can't loop around a guide during casting;
--and does not reduce the strength of the line.

Some examples of mainline loops, photos below:

1. Spliced End-Loop in hollow-weave Spectra. This is a thin, reliable way to form a line-doubler loop. There are no points of stress concentration and it is easy to make perfectly. The spliced End-Loop can be made in any loop size from fractions of an inch to feet. The catch is that you need hollow-weave Spectra.

If you prefer solid-weave Spectra as your mainline, a good alternative is to splice 5 to 10 yards of hollow-weave Spectra on top of the solid-weave and then make a spliced End-Loop. Glueless Solid to Hollow Splice

2. Bimini Twist. Thin and nearly 100% strong, the key to successfully using a Bimini Twist in a loop-to-loop connection is to use enough twists so that each side of the loop can carry 50% of the load. In my testing, that rarely happens below 30 initial twists--I say initial twists because about 60% of the twists you start with are used to create the top wraps, leaving only 40% of the initial twists to hold the connection. In my experience and testing 50 initial-twists is a good number. (Note, the loop-to-loop is a different application than tying a Bimini Twist to a Slim Beauty.) The final lock knot on the tag end of a Bimini should be superglued or it will loosen after a couple hours of casting.

The biggest drawback to the Bimini Twist is that it is difficult to control loop size, and large loops can catch on the guides during casting. More twists means a bigger loop, less twists means a risk of the knot slipping.

3. Surgeon's Loop. This is a quick, reliable, east-to-tie knot. And it is relatively easy to control loop size. The main drawbacks in a spinning reel application are: a) there is stress concentration where the mainline makes its first turn inside the knot, which reduces the strength of the mainline by about 30%, b) it is a knot that can hit the guides, and hang on them, and c) after an hour of casting, when the line on your spool is no longer packed tightly, it can pull wind-knot loops off the spool. The 30% strength loss is not usually a problem in 80# Spectra on a spinning reel, unless the particular line doesn't overtest (e.g. some of the PE lines).

All of the above choices will work, with some having advantages over the others. You can probably tell, I'm a big fan of the spliced End-Loop

[John from Madison CT]

Roger,
Excellent post!

[Sea Draggin]

Pamet,
Have you ever tested the breaking strength of a single overhand knot? I'm just wondering, because its something I have used a lot over the years.

Look forward to your insight.

Thx,
Jim

[paul708]

roger,
nice post, good info.
thanks

[pametfisher]

Pamet,
Have you ever tested the breaking strength of a single overhand knot? I'm just wondering, because its something I have used a lot over the years.

Look forward to your insight.

Thx,
Jim

That's really an excellent question. Yes, I have tested the single Overhand Knot. I'm curious though what you use it for.

The reason I like the single Overhand knot is for testing, but let me digress. Although this is not the conventional wisdom (however what I'm about to say has been recognized in technical literature for a hundred years or more), most properly made knots, in rope or fishing line, fail for one of two main reasons: 1) stress buildup at the first sharp turn in the knot; 2) not enough turns to create enough friction and the knot slips. (Notice that I didn't mention knots cutting themselves, heat buildup, etc.)

Since "not enough turns" is an easy problem to recognize and solve, stress concentration at the first turn becomes the biggest problem for most knots. A simple view of how stress concentration results in failure goes like this: when a line is bent around something very small (like another piece of line inside a knot), the material at the outside of the bend is stretched and carries most of the load, the line at the inside of the bend is not carrying much load. Then, since the load that was being carried by the full line before the bend (inside a knot) is now being carried by part of the line, the line effectively is smaller and it fractures from the load.

As a result, most properly made knots break from stress concentration at the first turn--even if they break at a short distance away from that point.

Knots with similar stress concentration: Clinch, Improved Clinch, Palomar, Uni, Jansik, etc. I group them in the 60-70% of a line's Actual Breaking Strength as measured (not the strength printed on the box). These knots all have sharp turns.

Knots with shallow first turns and 90-100% strength: Bimini Twist, PR, Mid, SIG and Slim Beauty.

Okay, so getting to your question, the Overhand knot is one of the weakest since it has very sharp turns and, it is easy to tie perfectly. So I put an Overhand knot it the middle of a piece of continuous line and check it's breaking strength. That tells me how strong my weakest knot will be for a given piece of line.

[Sea Draggin]

The above insight is spectacular.

I have used it for all sorts of applications. I think the reason the overhand knot has worked for me for loops and things is that I am doing it in a doubled line. There for instead of getting a 60% knot, I am actually getting more (120 in thoery) but knowing you can't get more than 100%.

[Nauti Natured]

Awesome information in this thread. I look forward to your future contributions!

[OCtuna]

This is an an excellent post.

[John from Madison CT]

Pamet: How sure are you about the Palomar being as weak as a 60% knot? I test all my tuna leaders, which have a Palomar at the hook and the swivel and they always test well above 60%. For example, I'll test 50lb Fluorocarbon to 40lbs with a Manley brass scale. The vast majority hold over 40lbs..

[pametfisher]

Pamet: How sure are you about the Palomar being as weak as a 60% knot? I test all my tuna leaders, which have a Palomar at the hook and the swivel and they always test well above 60%. For example, I'll test 50lb Fluorocarbon to 40lbs with a Manley brass scale. The vast majority hold over 40lbs..

Good question. The factors that influence the Palomar strength:

--What is the actual breaking strength of the line?

--Size of the terminal tackle: thicker, rounder wire means stronger knots.

--For that group of knots, range is 60-70%. That is 60-70% of the Actual Breaking Strength of the line in question, not what is printed on the box. The ABS is hard to measure without the right equipment/tools. Most line overtest substantially.

--Remember, not every knot is made perfectly. Especially if you make it in a hurry.

After testing many knots, I have given myself that range so that I don't get a bad surprise. Unless I have actually measured the line I'm using, I assume the Box number even though it is likely to be higher.

As a fish pulls line the drag goes up. I find the maximum number based on the initial drag I set. Then take the minimum number for the knot in question. If you've tested it ten times, use that number if you always tie it well. If you don't test, use the 60-70% of Box number. However, I recommend testing the line and testing the knots.