Knot breaking strenght testing
 

I hope I can explain this question properly..bear with me!

I've been watching Berley Knot Wars, and it is pretty interesting watching the breakung strengths of various popular knots.

A given knot is tied and the line is tied to a scale. Tension is pulled and the break weight is recorded.


Here's my question and an example..

Let's say we want to test a line to leader knot. We'll use 30# Seguar flurocarbon leader and 30# Power Pro.
We'll use a modified albright knot.

One end of our new rig is tied "somehow" to the scales and the other end must be anchored"somehow."

The "somehow" has be stumped! If the scales have an S hook, then we would need to tie a knot to hold the line.. and that knot may not be as strong as our albright, and we really don't want another knot in the test anyhow.

So how do they anchor off both ends of this rig? Some kind of a clamp?
Several half-hitches?
I dunno.
What say ya'll?I did call Berkley and they didn't have anyone around that could answer this question .

As long as the leader knot breaks before the other I assume it wouldn't matter.

On small filaments and fibers this is typically done by clamps, half hitching, or figure 8's.

Man you must have a lot of time on your hands to ponder such things so deeply lol!

http://arxiv.org/ftp/arxiv/papers/1202/1202.5260.pdf

We did an experiment like this a while back, see the paper.

If you look at figure 2, you'll see the fancy force gauge set up with the red rope and wooden handle.

To eliminate extra knots (other than the one being tested), one wraps the line around the wooden handle several times and secures it to the wooden handle with tape. The combination of friction from the wrapping and the tape secure the line without weakening it any with the tape. This is the best way to be sure only the strength of a single knot (or no knot at all) is being tested.

Thanks MathGeek!
That's the info I was after..
Good testing too!

It's a crying shame that MANY fishermen don't pay a whole lot of attention to their knots.
And when I have a little extra time on my hands,and can't get to the the water, you durn well betcha I'm testing various knots.. looking for just the right one when that 200# tarpon,50# redfish, 50#snook, or 13# speck comes along.

Oh well, I can dream big anyhow:D

How was the load speed controlled, or was there a consistent load vs. time throughout all of the tests?

They make very expensive machines to control load rates in materials testing. Google Instron, for example. These were too expensive for our testing, but it's not to hard with some practice for a skillful person to learn to apply a load in this range with a consistent load rate.

Look at the increase in the load over time shown in Figure 3. Since the loads are being measured as Force vs. time, it is simple to review all the force curves to ensure that the loadings are all occuring over about 1 second. Properties like breaking strength and fracture strength may depend very weakly on the loading rate. Increasing or decreasing the loading rate by a factor of 10 may change the breaking strength by 10-20%. Increasing or decreasing the loading rate by 10% will likely change the breaking strength by less than 1%.

An independent way of knowing that the method is not contributing much to the uncertainty is by observing that the certainties determined from the variations in the five trials with each line is only 1-3% for the lines without any knots. Once the knot is added, uncertainties increase to 1.5-15%. The variations in breaking strength from trial to trial depend much more strongly on whether there is a not than on the small variations from loading with a human pull rather than an expensive machine.

Few LA waters are clear enough for line visibility to be a big issue, especially when soaking crabs on the bottom for bull reds, so one can get strength by increasing the line diameter. We use 80 lb mono and have stopped paying for fluorocarbon. We still tie careful knots, inspect leaders often, and retie knots frequently.

But the study in the paper was motivated by our experiences trolling for trout with spoons in Colorado's gin clear mountain reservoirs. We needed to keep the line diameter down both for invisibility and proper lure action. We'd been using Seguar Grand Max Fluorocarbon for a couple years and figured since it was expensive and name brand, it must be pretty good. It did catch a lot of fish, but we lost a few big trout unexpectedly, so we began to look at the knot strength.

After the experiment, we switched to Ande, which is really great stuff. With a little care tying a uni knot, the knotted strength retains the rated strength of the leader material. We considered re-doing these kind of force experiments after fishing for a day to see how much strength is lost through a day of use, but we instead just kept replacing the leader material and retying after a few hours of use.

A scale is a great tool to learn to tie good knots. Poor knots reduce line strength more than any other factor, at least until it gets nicked. And nicks are easy to spot.

Is the modified Albright the same as the "Alberto knot?" I've used this for the past few months with #30 braid to #10 and smaller fluoro, and haven't broke the knot yet. They have the "Knot Wars" as an app also.

We gave up on braid to mono knots a few years back after trying a number of things and having them fail to often. We tie in a swivel now. Two uni knots tied to a swivel is much more reliable than the braid to mono attempts.

I haven't tried it with braid to mono, only with fluoro. It's ideal for having longer (3'+) leaders. It's a long skinny knot that doesn't get beat up as bad going through the rod eyes. I think that's why it was designed, to use when a barrel swivel can't be used. Were your knots actually breaking, or would the knot start to slip? I've tried the Alberto with fluoro to fluoro just to keep from having to re-spool and the knot wouldn't catch and would pull out. Might just be the slickness of the lines not allowing the knot to bind down correctly. A good practice (if using new braid) is to grab the section of braid before tying, and pull down the length of it a few times to get the slick coating off of it (again, helping it bind down with less slip). I think that even the slightest slip of your knot can significantly reduce the strength of your leader material. Just a thought.

Here you MG. Might not work as good with mono though not sure.

https://www.youtube.com/watch?v=J56O3CZVu7M

That looks like a great knot. Lots of great striper pics also. I bet this knot will work.

However, after fishing so successfully with to uni knots connecting to a barrel swivel for several years now with no failures, it's hard to go back and try again with the ALberto knot, at least for situations where casting with the swivel is not a problem. If we need to reel the knot up into the guides, I think we will give the Alberto knot a try. It is a very clever knot design.

O no doubt, use the swivel if you can.

I've been using this attaching braid to mono and fluorocarbon for a couple years now with zero knot failures.

I'm truly happy that this thread is getting some good,intelligent and interesting replies.
Again, thanks MathGeek for getting that ball moving!

I live in East Texas and grew up fishing Murval, Monticello and guiding on Fork. Spent the last 20 years guiding tarpon trips in SW Florida.
There are times in the gin clear waters of various Florida locations that swivels were not an option. And large diameter mono is/was not an option.
Period!

Braid to fluoro was THE option.
And like the search for the Holy Grail.. the smallest and simplest knot to connect the two has been the prize:)

You fellers have a great resource in your back yard. Continue to cherish it.. and damn sure take care of it.

It is such a shame to kill all those tarpon during the Tarpon Rodeo. Wish you guys could come up with a decent and fair "no kill" tournament platform.