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Definitive knot test

Started by scotty9, October 14, 2009, 12:04:42 AM

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Wildfisher

Norm,  in order to do this scientifically  you need a set up that can be  verified as  repeatable and finding  a suitable (i.e. affordable)  transducer / load cell is a problem.

Malcolm

There was a 20 fluorocarbon test done in the 2006 Trout Fisherman magazine (sorry - bought at Schipol Airport airport as I had run out of newspapers). A lot of the fluorocarbons are still around to my certain knowledge. Quite interesting results - Hardy and Drennan are known for their reliability - not surprising as they both broke way over their advised BS but were also much thicker. The test was done in the Masterline factory with very precise machinery and the line pulled at a constant rate until broken.
There's nocht sae sober as a man blin drunk.
I maun hae goat an unco bellyfu'
To jaw like this

scotty9

Guys thanks for all the suggestions, I have done some further testing with different leader materials and will make a post in a couple hours once I have time to sit down and write it out. Will also answer the questions that have been posted. Some interesting twists when leader material is changed....

Wildfisher

Quote from: claretbumble on October 14, 2009, 04:25:46 PM
Ooooohh, very good!

We love a good pun on here - that one had me knotted with laughter! We'll need to rope you into the Pun Club (Hon Pres: River Chatter). Or maybe you're a little tied up this afternoon?



For such puns you should be highly strung.  :D

scotty9

#14
Part 2

Here we go....

For clarification, the half blood knot i referred to was indeed the tucked version, also known as the improved clinch knot. Also for clarification, to those who say it needs to be wetted carefully and bedded down carefully and i may have tied it wrong - it was tied exactly the way it should be. Remember this is testing to destruction, through pulling force. When playing a fish you exert very little force on the line due to the spring action of the rod. Hence why it seems reliable. I am saying it is not as strong as the other knots tested, probably still fine for fishing (i've never had it fail either!).

The Second Test:

Upon request i tested the knots again, pitting them against each other in the same manner. This time however i used:

6lb Airflo G3 Fluorocarbon (3x diameter)
6.4lb Fulling Mill World Class Co-polymer (4x diameter)

Again, as expected the tucked half blood knot was the weakest of the lot. Here's where the major surprise was:

The Uni knot was the second weakest again BUT the strongest knot was determined by leader material. When using fluorocarbon, the Davy knot was the strongest, beating the Grinner knot. When using the co-polymer the Davy knot was the strongest! To ensure this was not an anomoly, i tested each twice.

Further thoughts:

I realise everyone has their favourites and that the tucked half blood knot is probably used by most and does well. However this test shows it is infact the weakest of pretty much all the knots that you can attach a fly with. There are more knots than the ones in this list but some are impractical for flies and these seem to be the most common. As i mentioned earlier due to the spring of the rod you actually exert very little force on a fish, and thank goodness for that since the knots seem to reduce breaking strength quite dramatically. People with very, very tippy rods may wish to check which knots they use?!

Conclusion:

If using co-polymer and i suspect most "monofilaments" are nowadays, such as stroft, fulling mill, frog hair etc then the knot strength in order of descending strength is:


  • Grinner knot
  • Davy knot
  • Uni knot
  • Tucked half blood knot

If using fluorocarbon then in my testing the knot strength in order of descending strength is:


  • Davy knot
  • Grinner knot
  • Uni knot
  • Tucked half blood knot

Final thoughts:

I have limitations to what i can do. I have not carried this out as i would in a laboratory as i simply do not have the resources i would need at home. It was a quick rig drawn up to briefly test knot strength and i found the results worthy of publishing. The other thing was these were the only types of tippet i had around, i've been exclusively using stroft this season. I had the spool of fluoro, don't use it though. I like the fulling mill stuff, seems very strong. I am unable to test the "shock" strength as well, too difficult a setup for my basic experiment!

Norm - i have included a photo especially for you, very, very simple as you can see! I'm sure you were expecting more. The main problem is attaching the line to a newton meter in order to test actual breaking strain. I firstly tied a perfection loop and put the hook through the loop. Turns out that knots to ties loops are even weaker. I ended up holding the end of the line with forceps and then wrapping around the hook of the newton meter around 15 times, this enabled enough grip and breaking strain to test the knot to destruction. Not ideal but was the best i could do. Maybe your pupils could come up with a better one? The photo is not the best, but when trying to photograph the full setup you couldn't see anything. Basically as you see in photo, line tied with one knot to a fly held in forceps and another knot at the other end done the same way. Pull till it breaks  :D



Soldier palmers were used as they were cheap flies i never used so no fear of damaging/bending the hook.

One more thing - the Davy knot tied with two tucks is pictured. As you can see it is a tiny knot, bear in mind that is 3x (pretty thick) 6lb fluoro in the photo!

Inspiration - thanks to Alex for the idea, he inspired the idea after a conversation on sunday about the uni knot and davy knot. He suggested the rig and turns out it was a damn good idea.

Wildfisher

Good work Scott, thanks  for making the effort and attempting to share it with the  old dinnae-try-tae-tell-me-anything-new-cuz-I'm-set-in-my-ways-so-I'll-just -do-what-I've-always-done codgers.  :lol:

I exclude myself from that group obviously.    :makefun


Pointy Shadow

Thanks Scott.

It has confirmed my suspicions that the Davy is the strongest for 100% flouro.

Just as well as I use 4 or 6lb Spiderwire or 4lb Seaguar Red Label :)

Pointy Shadow

Breac - once you start to use the Davy Knot you wont go back to using anything else. :)

scotty9

Quote from: Pointy Shadow on October 14, 2009, 10:00:38 PM
Breac - once you start to use the Davy Knot you wont go back to using anything else. :)

Or the Grinner if you are not using fluoro :lol:

scotty9

Quote from: claretbumble on October 14, 2009, 10:48:31 PM
Harrumph.

That Davy Knot looks too simple, and that Grinner looks too complicated. Like Daddy Bear, the Half Blood is "just right" for me!  :lol:

You're one of those something-something-codgers Fred was talking aboot aren't you?  :makefun

Davy knot looks too simple but is remarkably strong as proved in my test. Try it  :shock: The grinner is actually very easy. When i looked up how to tie the uni knot and grinner, i thought feck i'm never going to learn these. 2 mins later i can tie them without reference.

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