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Some thoughts on Bernd's thoughts on stretch in fly lines

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Viking Lars
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Some thoughts on Bernd's thoughts on stretch in fly lines

#1

Post by Viking Lars » Wed Oct 06, 2021 8:21 am

Bernd is one of the most systematic fly fishers I know and quite possibly the one in my "circle of people" who spends the most effort (both through thinking, time and effort) improving and maximising the chance of succes. I'm rarely one to disagree with Bernd, yet when it comes to the issue of fly line stretch I have a few issues to discuss :)
The more stretch we add, the harder it gets to add aggressive jumps to our fly. Whenever we need these I prefer low stretch for sure! No need to tell, that without a take we have no need to talk about the rest! This is for example very critical on asp. Too much stretch and I often fail to get a bite!
- This made we wonder - how much force is needed to impart an aggressive jump to the fly? Is that force enough for stretch to have a noticeable impact? I am interested in how you tested this, Bernd. And at what distances? As you noted your self a flyline with stretch stretches further the longer it is. How much stretch can we really impart of a fly line with a say 1m long sharp pull, with only the water acting against us?
And when you say you get fewer bites when fishing a line with stretch, are you really experiencing noticeably less takes than with fishing non-stretch cores?

I agree that in many applications low-stretch to a certain degree preferable. It stands to reason that less stretch makes it easier to set the hook. The obvious question then is how much force is really needed for the hook point to penetrate and does this amount of force really have that big an impact on stretching a fly line? And of course - does the amount a stress a fish imparts on the lines when taking the fly really make us detact noticeably less strikes? I agree that is *can* be the case. Picky can be really soft strikers. I have never done any testing to compare, but honestly, I doubt that the difference would be significant. When retrieving a fly, I believe that I feel every bounce on a rock, every slight snag on a weed, but of course - I *believe*, I can't be sure.

I think we need a few underwater Go-Pros and some testing next time we catch up :-).

Lars

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Re: Some thoughts on Bernd's thoughts on stretch in fly lines

#2

Post by Paul Arden » Wed Oct 06, 2021 8:41 am

When Tim says it’s fair to say barstool got it wrong in the past that’s understatement of the year. The big problems were permanent memory and flylines that snapped in mid cast. Imagine making a cast and the fly line snaps :D Or worse still one the retrieves itself into a coiled mass at your rod tip. Take detection was worse, not better, because there was 20m of slack between you and your fly :laugh: :laugh:
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James9118
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Re: Some thoughts on Bernd's thoughts on stretch in fly lines

#3

Post by James9118 » Wed Oct 06, 2021 1:30 pm

We have to be careful when comparing fly lines using terms such as 'stretch' (strain). What we actually need for a valid comparison is stress per unit of stretch, i.e. modulus. This levels the playing field in the measurement.

As it stands, if you say a fly-line stretches 20%, all that's really being said is 'I didn't want to pull it any harder' unless you did of course take it to the breaking point :-) A better test is to tie one end to a balance and pull the same load into each line, noting the extension.

If anyone wants to see some mechanical tests on various fly lines (taken to the point of failure) then feel free to send me some samples - I'll need about 30 - 40cm of each.

James

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Re: Some thoughts on Bernd's thoughts on stretch in fly lines

#4

Post by Paul Arden » Wed Oct 06, 2021 1:44 pm

I have a lot of old flylines here James. I’m sure between us we might be able to come up with something. We might even be able to get hold of manufacturers’ samples for an experiment.

I’ve broken a few flylines in testing. That’s how I accidentally discovered that SA sinking lines have a weaker core than floating lines (8WTs - 22lbs vs 35lbs). Here flyline strength is more critical than stretch but both would be good numbers to have.

Maybe we could come up with a modulus experiment to compare lines without pinging them? We still have those datatables to complete with AFFTA weights.

Cheers, Paul
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Re: Some thoughts on Bernd's thoughts on stretch in fly lines

#5

Post by James9118 » Wed Oct 06, 2021 2:36 pm

I'm sure we can come up with a fairly simple test requiring minimal equipment i.e. a ruler, and something to measure load i.e. a balance. To calculate stress you need to be able to measure the lines diameter also - that's something people should bear in mind, you can't compare different #AFFTA lines without taking account of the different cross-sectional area.

I'd like to see the difference between a 'tropics' line and a normal 'cold water' one.

Yes, we don't need to break the lines to get the modulii figures.

Incidentally, I once inspected a line that had just been used to land a large yellowfin tuna - it had a very interesting spiral delamination where the coating was split from the core.

Cheers, James

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Re: Some thoughts on Bernd's thoughts on stretch in fly lines

#6

Post by Lasse Karlsson » Wed Oct 06, 2021 3:10 pm

I don't think there is a flyline out there that has 20% stretch, that figure from Tim is as reliable as when Paul talks about his 20 feet initial loops distance casting ;-)

What kind of lines would you like James? have a few boxes of weird stuff :-D

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Lasse
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Re: Some thoughts on Bernd's thoughts on stretch in fly lines

#7

Post by Paul Arden » Wed Oct 06, 2021 3:17 pm

:D :D :D
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Re: Some thoughts on Bernd's thoughts on stretch in fly lines

#8

Post by Bernd Ziesche » Thu Oct 07, 2021 9:07 am

Viking Lars wrote:
Wed Oct 06, 2021 8:21 am
- This made we wonder - how much force is needed to impart an aggressive jump to the fly?
Good questions, mate! (hello Lars ;) )
When I was fishing for Bonefish more than 2 decades ago, I learnt how to turn a Bone 180° in his direction (after not having got into a proper casting position quickly enough). Mostly this was needed, while the Bones were swimming fast with the incoming tide.
I needed one strong (sharp) pull. If it was just a little softer, nearly no Bone would turn. I couldn't tell, if they did not feel the fly in their back (about 2 to 5m behind the fish), when not pulling truly strong, or if it just wasn't telling them, that there was easy bait worth to turn maybe. But I realized clearly, how big the reactions depended on matching the strength of pull precisely. After those fish turned I spooked many when doing the same strong pull again! Now it had to be little less strong.
Since that time I always focused on what sort of pulls would cause what reaction. On pike for example it can be (and often is) a huge difference (15 in 2 hours or zero!), if I pull truly strong (sharp) or little softer. If you have not tried this yet. Do it! You will be very surprised soon.
How much force in detail... different from situation to situation and species of fish to species of fish.
I studied this a lot especially on Pike, Zander, Asp, Sea trout and for sure always when sight fishing for whatever species of fish. The differencies in the fish his reaction very often were remarkable.
Viking Lars wrote:
Wed Oct 06, 2021 8:21 am
Is that force enough for stretch to have a noticeable impact? I am interested in how you tested this, Bernd. And at what distances? As you noted your self a flyline with stretch stretches further the longer it is. How much stretch can we really impart of a fly line with a say 1m long sharp pull, with only the water acting against us?
We have to differentiate between a lot of factors. Let's start with stretch in general (not fly line stretch only). When I fish for asp using a shock absorber of 20cm stretch length, it softens fly movement. How do I know? I see it and I get a very clear answer of many fish (strike vs. no strike). Of course the fly itself can provide more or less resistance having an impact here, too. Your thoughts here are correct.
Before I found Drennan power gum, I built several different shock absorbers with elastic rubber band. It was possible to break some stripping wise sometimes. This already showed me, that my pulls went right into the stretch! They were not too easy stretchable, but breaking strength was way too low. To be fair, I used quite some heavy flies sometimes.
How much stretch can we add to a fly line stripping wise you asked. Not much, but 5cm softens our pull significantly - especially on short distance pulls. I have zero doubt here.
Viking Lars wrote:
Wed Oct 06, 2021 8:21 am
And when you say you get fewer bites when fishing a line with stretch, are you really experiencing noticeably less takes than with fishing non-stretch cores?
When I change from asp (using a shock absorber) to Zander = sometimes just changing the leader (no shock absorber) and forgot to remove the shock absorber, I 100% failed on Zander. A shock absorber makes it mostly impossible to feel the take and to set the hook in case the fish keeps the fly. For asp it's amazing (hard to believe for me often) how a tiny tiny increase in stripping force (sharpness) changes everything from zero take into 8 in a row. I have experienced this more than 100 times in the past maybe 10 years. No doubt the differency between adding a 20cm stretchable shock absorber or not is detactable in the fish his reaction.
Viking Lars wrote:
Wed Oct 06, 2021 8:21 am
I agree that in many applications low-stretch to a certain degree preferable. It stands to reason that less stretch makes it easier to set the hook. The obvious question then is how much force is really needed for the hook point to penetrate and does this amount of force really have that big an impact on stretching a fly line? And of course - does the amount a stress a fish imparts on the lines when taking the fly really make us detact noticeably less strikes?
Try this:
Put your 2 lines all length on the grass. Ask your daughter to give similiar pulls on both a) low strech fly line and b) high stretch fly line. Ask her to add both soft and strong pulls both on short distance pull and on a longer distance pull. I bet you'll agree with me to be able to tell which line it is even when blind folded. What force you'll feel clearly differs from line to line. I of course know, that you'll tell me to hold the end of a line is different from having just a fly hanging to it yet being free in the water. And I agree of course. Try to hold the end of the line very softly and tell your daugther to start with very gentle pulls. You'll feel it!

Bottom line:
I know too well where you are coming from, because I was very surprised myself how big these impacts are!

After I found all this I checked with spin fishermen again. Well, the experts here have all figured this a long time ago. We missed it!
Regards
Bernd

P.s.: Let me offer one more experience: I saw many fish taking my fly without being able to feel the take. Happened with large pike, Zander, asp, Atlantic salmon, Sea trout and more. We clearly miss a hell lot of takes. Remember the cause of Czech nymphing... When I hold my friend Hansi his dropshot rod to feel a Zander take/strike, a 40cm Zander feels like for me 80cm on fly. The bigger they are, the stronger they suck in the bait. My line system absorbs a lot still. He thinks in terms of 0,25mm nylon vs. 0.12mm "fireline" to decide weather he misses a lot of takes or not. Our problems are much bigger!
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Re: Some thoughts on Bernd's thoughts on stretch in fly lines

#9

Post by Bernd Ziesche » Thu Oct 07, 2021 9:26 am

James9118 wrote:
Wed Oct 06, 2021 1:30 pm
A better test is to tie one end to a balance and pull the same load into each line, noting the extension.
If anyone wants to see some mechanical tests on various fly lines (taken to the point of failure) then feel free to send me some samples - I'll need about 30 - 40cm of each.
Hi James,
thanks for the offer.
I had the same idea (I think) about adding a specific pull. One idea was to add a bucket with water in over a pulley. The other ne was adding my scale and pull a certain weight.
In regard of fishing I would want to change the level of pull varing with line class, I think. I believe this may result in more realistic numbers. Would have to run a lot of tests to really get the full picture. Ok, I am working with stretch now for some years, but it still feels very very new and I have a lot to learn about it left.
Would love to come over and we create a test procedure. I would brink Lars as well. :pirate: :sorcerer:
Regards
Bernd
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Re: Some thoughts on Bernd's thoughts on stretch in fly lines

#10

Post by Bernd Ziesche » Thu Oct 07, 2021 9:31 am

Lasse Karlsson wrote:
Wed Oct 06, 2021 3:10 pm
I don't think there is a flyline out there that has 20% stretch, that figure from Tim is as reliable as when Paul talks about his 20 feet initial loops distance casting ;-)
Hello Lasse,
agree of course.
I have many fly lines at home. None provides more than maybe 10 to 13% when unrealistic strong pulling. I think 2 to 8% is matching for 95% of lines in 95% of real fishing situations.
6m stretch on 30m would make control of a lot of things impossible. :D
Cheers
Bernd
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