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

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

Hi George,
yes Greys Point Bonefish in. I was lucky to have been invited for the first group. Cudas, I could catch it, when seeing one. Just a year later, this was different. About Bonefish we caught more than I liked. It was many every day. Felt too easy. Some guides were not too good, but one was. Next year I went to stay at his house and we went only with him for 2 weeks. That was pretty cool! I learnt a lot about how Bones and Cudas behave in relation to fishing pressure. Second year when coming closer to the lodge area, all fish were already much harder to be fooled. Luckily we again had new water for us with that one guide (Fidel).
The guides in the Keys for example of course were in another league of skills!
Regards
Bernd
http://www.first-cast.de
The first cast is always the best cast.

James9118
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Location: N.Wales

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

This is a Grey's Point cuda - Tracy and I DiY fished out of the lodge a number of years back.

Mangrove Cuckoo
Posts: 579
Joined: Tue Jan 29, 2013 7:51 am

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

Well, this "hard strip" technique might just open a whole new universe of possibilities for me. I can't wait to give it a try!

Snook are quite similar to a saltwater version of pike. And they have a very prominent black lateral line that is reported to be a vibration detector of sorts.

The flyfishing difficulty (or challenge) lies in their acute eyesight, up-looking eyes, and penchant to occupy shallow clear water during parts of the year. Otherwise, they are rather aggressive omnivores... but I believe sight fishing them with a flyrod puts them in candidacy for the ultimate challenge. (Sorry Paul!)

Bonefish, redfish, and permit are all "tailers"... so casting to them when their heads are down is almost too easy.

But with snook... cast too close and they either spook or become guarded, cast too far and they don't detect the fly, move the fly in any way toward them and they panic. Damned if you do...

I never considered casting behind them on purpose! (Not that I haven't done it by mistake many times) But, I never thought of stripping hard to get their attention either!

Hard stripping all the time is a common fault of many novice fly anglers around here. The idea of prompting the "reaction bite" is a worn-out old fashioned idea that may have been valid long ago, but saying that the fish seem to be quite put off by it, the vast majority of the time, is a huge understatement.

Casting behind a snook should greatly reduce the chance of them detecting the line in the air. And with their super sensitive lateral line, they can probably detect the hard strip easier than most other species. When or if they turn, the fly will already be in the water waiting for them!

Damn... I wish I thought of this, say 20 years ago...

Bernd!
"Technique is the proof of your seriousness"

Wallace Stevens

Torsten
Posts: 249
Joined: Tue Jan 22, 2013 7:34 pm

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

Hi,

some thoughts:

* stretch figures make only sense, if you specify the test force

* Young's modulus is OK to quantify a certain material; but because a fly line consists of different material and I'm sure the core dominates the stretch behaviour I'd rather use something like stiffness; force divided by the displacement or strain

* The guys from the German fly fishing forum have already a standardized method; they employ a test weight of 1,8 kg and record the strain in % ( $$e = \frac{\Delta L}{L}$$ )

I don't know why 1,8kg was chosen; I'm guessing it's still in the linear range, but think this is quite easy and straightforward to measure with tools at home; perhaps good enough for relative comparisons. I've tried that with two of these chinese lines - just made two marks at 50 cm spacing on the line, added a test weight of 1,8 kg and measured the elongulation. For the two lines I've got a value of ~8% @ 1,8kg. You can find a lot of examples here:
https://www.fliegenfischer-forum.de/flischnu.html
Some lines from barstool and Rio have indeed some low stretch values (e.g. RIO InTouch Technical Trout 1% @ 1,8 kg). Lines from SA seem to have 5% @ 1,8kg.

For a more sophisticated test you would simply record the elongation at different test weights e.g. at 100 grams steps until breakage and then you can draw a chart from that.

I don't know if we can draw any conclusion from these values however! 1,8 kg or roughly 18N is a quite large force, e.g. while retrieving a fly I'm sure the tension (or pulling force) is much lower.

Thanks,
Torsten

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

Thanks Torsten. Some good info in there. Yep I don’t see it affecting fly action. I would be surprised if there is much stretch in flycasting… possibly at overhang? We still have the wrinkles with non-stretch lines I assume?

Cheers, Paul
It's an exploration; bring a flyrod.

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Nick
Posts: 250
Joined: Sat Jan 19, 2013 5:15 pm

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

I have been known to bang on a bit about fly line stretch in the past. I had never considered that there might be a change in the movement of the fly due to fly line stretch - I am not convinced that it would be a significant one even if there was. I do think that there is a difference in detection of takes with non stretch vs standard lines. I had one of those old barstool lines and I was quite certain that I caught more fish with it than I would have otherwise done, especially when fishing nymphs very very slowly in Stillwater. However, I think the main benefit is in setting the hook. At long range the stretch in a standard fly line is definitely enough that getting a hook to stick is much much harder. Makes sense if there’s 5% vs 1% stretch. At 20m that’s the difference between a strip-set of 20cm vs a meter.

I think the setup that Torsten described could be a good way to go. Easily replicated by anyone. It might be good to also test with a lighter weight, 500 grams? Also might be interesting to see if the belly section of the line with thick coating, stretches significantly less than the running line with thin coating.

Mangrove Cuckoo
Posts: 579
Joined: Tue Jan 29, 2013 7:51 am

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

Over the last few years I have been testing lines for some folks and I am shocked at how much difference there is depending on the core materials.

Trying lines back to back it is very easy to feel the difference, especially at longish distances.

At one time I was convinced that low stretch cores were superior when fishing for tarpon. Now I am rethinking. For sure, hook sets are better but it is not like the take is difficult to detect. So, sensitivity in this case is not important.

However, i have broken off more leaders when the tarpon go airborne when using stiff cores. Like never when using stretch protected lines, and significantly more than usual when using the very low stretch ones. Surprisingly, this happened predominantly on small fish and low # rods.

So, I guess, as in many things you cannot make absolute statements that A is better tha B. Pick the characteristic that you find best for the conditions. Knowing what you are getting is unquestionably a good thing though!

For me, I'm going back to "regular" stretch lines for the smaller tarpon. I don't care if I stick a few less, but I really don't care for retying leaders when I'm on the water.
"Technique is the proof of your seriousness"

Wallace Stevens

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

I also think about the stretch on setting the hook but how much force is actually used to set the hook? Even with a SW strip set, playing around with a spring balance, I would be very surprised if we set with much more than about 3KG. That’s already quite a pull and should certainly be enough to set a pointed hook!

I have a two year old SA Bonefish line than I use on the HT6 for Gourami. It had terrible memory, so yesterday I stretched it a few times and now it lays straight again. The ability to do that I think supersedes a small increase in sensitivity because if the line has memory and lays in coils then take detection is far worse than a little stretch! Particularly in this case where I’m fishing static presentations.

It would be interesting to test some for comparison. I’ll have a chat with Rio.

Cheers, Paul
It's an exploration; bring a flyrod.

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sms
Posts: 396
Joined: Thu Jan 10, 2013 7:12 pm
Location: Southern Finland

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

For my passion, tuna on fly, the best line material IMO is the Rio leviathan. A bit stretchy monocore enables it to stretched straight even below its normal operating temperatures. Add straightness to stiffness and you get a lot less tangles. And tangles kill opportunities.
I'm here just for the chicks.

-Sakke

gordonjudd
Posts: 1438
Joined: Sat Jan 19, 2013 11:36 pm
Location: Southern California

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

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.
James,
This will be an interesting experiment and may turn out to be a bit tricky in that I would expect the line will have a non-linear spring constant curve like a rubber band.

This https://www.wired.com/2012/08/do-rubber ... ke-springs topic shows that the force vs deflection curve for a rubber band depends on the measurement rates and may have some hysteresis when the stretch is relaxed.

Gordy