Understanding Fly Lines

tangled

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The simple explanation to your question is transfer of energy - far more efficient with a taper, leading to an acceptable presentation, than with a level line.

Ok, hence the double taper which is really a flat line with a taper at the end. (The GT90 has only 10’ of taper).

Then along comes the WF which on the face of it introduces a reverse taper into the middle of the line which should hinder energy transfer?

Which takes us back to Moray's post

GT90 Front taper & tip = 10’
Belly =. 20’
Rear taper = 43’
Running line =. 17’

SLX Front taper & tip = 24.5’
Belly = 4’
Rear taper = 4.5’
Running line = 57’

The Barrio website states that both these lines are intended to be true to weight measured at 30’
Presumably there is minimal weight in the running line, compared to the head. So at 30’ we are actually weighing almost all of the casting weight in the SLX (90.9%).
By comparison, at 30’ we are only weighing about 41% of the total weight in the head of the GT90, there is another 43’ of rear taper not accounted for by this standard.
You can obviously carry a lot more line in the air with the GT90 with the weight outside the rod getting heavier each time you slip line into a false cast.
If you weighed the full head length of both of these lines, they must be different and yet they could both be a #5 or whatever.

Both those line hit their rear taper at or about 30’ with the SLX having a very short belly (flat line) giving you only 3’ after 30’ before you're into thin running line.

It really sounds like you shouldn't have more than 30' of line out for either doesn't it?
 

PaulD

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Then along comes the WF which on the face of it introduces a reverse taper into the middle of the line which should hinder energy transfer?

It really sounds like you shouldn't have more than 30' of line out for either doesn't it?

With weight forwards, the ones with a limited rear taper . . . yes. That's what they were designed to do - the majority of casters can comfortably hold (?) 30ft of line in the air and should be able to shoot the thin level running line.

The Airflo 40 Plus Expert has a head of 45ft for those who can aerialize a head of that length..

It's how we used to make shooting heads . . . buy a DT, take it to a field and see how much you could consistently hold in the air outside the rod tip . . . cut it there and join it to 30lb Fluorescent yellow Stren. When casting you'd have 3 or 4ft of Stren outside the rod tip - effectively the same as a WF with a short back taper.
 

tangled

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The Airflo 40 Plus Expert has a head of 45ft for those who can aerialize a head of that length..

With that line are they still saying that, say, a #5, is still the correct weight at 30’ or at 45’? If correct at 30’, you're essentially overlining your rod considerably at 45'.
 

PaulD

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With that line are they still saying that, say, a #5, is still the correct weight at 30’ or at 45’? If correct at 30’, you're essentially overlining your rod considerably at 45'.
Well yes, to conform to the AFTM scale, minus the level tip, the first 30ft should be of the order 9.07g.

However, if you weighed the first 30ft of the original Airflo 40+ lines you would have discovered they weighed in at some 2 AFTM sizes greater than that written on the box. This may be a clue as to why some people laud the 40+ as 'great casting lines'.
 

tangled

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Well yes, to conform to the AFTM scale, minus the level tip, the first 30ft should be of the order 9.07g.

However, if you weighed the first 30ft of the original Airflo 40+ lines you would have discovered they weighed in at some 2 AFTM sizes greater than that written on the box. This may be a clue as to why some people laud the 40+ as 'great casting lines'.

So the bloody thing would be 3 or 4 sizes heavier at 45 feet...
 

James9118

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Ok, hence the double taper which is really a flat line with a taper at the end. (The GT90 has only 10’ of taper).

Then along comes the WF which on the face of it introduces a reverse taper into the middle of the line which should hinder energy transfer?

Which takes us back to Moray's post



Both those line hit their rear taper at or about 30’ with the SLX having a very short belly (flat line) giving you only 3’ after 30’ before you're into thin running line.

It really sounds like you shouldn't have more than 30' of line out for either doesn't it?
I think some explanation of how fly lines 'roll out' is needed here. Now this is a contentious issue and there's an awful lot of bollox written by people who think they understand it (and the underlying physics) but actually they're just in the business of flogging tackle.

'Energy transfer' is one of the terms that just leads to confusion. I think most people with some common sense will agree that the (kinetic) energy of the line is at a maximum immediately after the fly caster's input is finished i.e. once the line starts overtaking the rod tip. From this point forward the only thing that happens is kinetic energy loss, ending ultimately with the line laying out possessing zero KE. So the key thing is how this KE loss occurs - and how the fly line taper affects it.

I don't want to turn this into a physics discussion, I think that's best left for Sexyloops, but if someone wants some additional reading they should look up the conservation of energy laws, particularly the conservation of angular momentum.

What angular momentum considerations will tell you is that a spey type taper (triangular) will turn-over quite 'aggressively'. This is great especially for roll casts etc. where you want to lift the anchor out of the water and deliver it to the target. The reason I don't like them for overhead (distance) casting is because this 'aggressive' turnover results in the cast straightening too early, and once the line is straight the forward shoot is compromised.

For distance casting therefore, I want to slow down the turnover in order to maximise the flight time. This relies on the opposite angular momentum effect, i.e. if the line is going from thin to thick as it rotates around the loop it will slow down. This is exactly why distance casters want to cast with overhang behind their WF heads - this means there's a transition from thin running line to the thicker head. This means the turnover of the head itself is slowed and (hopefully) the line straightens just before it touches down. Getting this overhang correct is a skill that all good distance caster master.

Going back to the GT90 line in the example above, if you really wanted this line to cast far you'd aerialise it right to the end of the rear taper, i.e. carrying 70ft plus of line. Very, very few caster possess the skill required to do this though.

James
 
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tangled

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Depends upon the belly / taper ratio . . .
Sure, but for the sake of argument, we know that the first 30' of a #5 weighs 140 grains, so ignoring the taper, that's 4.7 grains per foot. @ 15’ we get 70 grains. 70+140=210 which in an #8.
 

tangled

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No it doesn't work like that - the standard relates to the first 30ft (+ tip) only. There is no standard for the next 99 feet

Sure, I understand the standard, but in practice the weight of line aerialised is equivalent to using, let's say, an #8 at 30’.
 

James9118

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Sure, I understand the standard, but in practice the weight of line aerialised is equivalent to using, let's say, an #8 at 30’.
Another thing that can go wrong on threads like this is a purely 'theoretical' approach with no recourse to empirical observations.

I can aerialise a lot of line. I routinely practice carrying up to ~90ft (for competition purposes). What I can say with confidence is that 90ft of a #5 line still 'feels' lighter in the air than 30ft of say #9 or #10 weight line, despite the fact that on a balance they may weigh the same.

There's a big difference between casting a 'point' mass i.e. a lead weight, versus a distributed mass i.e. a fly line.

James
 
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glas y dorlan

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Where does Airflo’s “booby basher” line fall into all this I wonder? Don’t they advocate cutting the head to suit the individual’s casting?
Why doesn’t that apply to all fly lines then?
Do AFTM ratings even enter the equation if you’re going to chop bits so to speak?
 

tangled

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I can aerialise a lot of line. I routinely practice carrying up to ~90ft (for competition purposes).

Yikes...

What I can say with confidence is that 90ft of a #5 line still 'feels' lighter in the air than 30ft of say #9 or #10 weight line, despite the fact that on a balance they may weigh the same.

Do you mean 90’ on a #5 rod compared to 30' on an #8 or #9 rod? If so I can understand that. A #9 is a beast.
 

James9118

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Yikes...



Do you mean 90’ on a #5 rod compared to 30' on an #8 or #9 rod? If so I can understand that. A #9 is a beast.
The rod doesn't really matter. For example, imagine I have two shooting heads that weigh the same amount e.g. 20g. One is 30ft long and the other is 60ft long (so they're cut from different AFTTA weight lines) . I then cast these two lines on the same rod (it doesn't matter which one) - the 60ft line will always 'feel' lighter than the 30ft one.

James
 

PaulD

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Where does Airflo’s “booby basher” line fall into all this I wonder? Don’t they advocate cutting the head to suit the individual’s casting?
Why doesn’t that apply to all fly lines then?
Do AFTM ratings even enter the equation if you’re going to chop bits so to speak?
Ths line has a whopping 150ft total length and the 55ft head length has a 400 grains weight. The head is designed to be cut to your desired length and to suit the conditions and rod you are casting with.

If you're holding the 55ft in the air, 400 grains is the top end of a 12 wt.

It needs to be remembered that the AFTM number is a guide, not an answer. Consider two anglers, one uses a 9ft, 5wt to fish a river, the other uses his 9ft, 5wt to fish dries from the bank of a still water - despite both their rods saying 5wt, what each angler needs from his line is probably entirely different. They need to consider how that 5 wt lines weight is distributed - its belly and taper profile - to enable them to present their flies in the way they need to.
 

tangled

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Consider two anglers, one uses a 9ft, 5wt to fish a river, the other uses his 9ft, 5wt to fish dries from the bank of a still water - despite both their rods saying 5wt, what each angler needs from his line is probably entirely different. They need to consider how that 5 wt lines weight is distributed - its belly and taper profile - to enable them to present their flies in the way they need to.

And the question remains which type of line is best where? Can put together some simple rules of thumb?
 

tangled

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There are 74 single handed fly lines for sale on the Scientific Angler's website


Confronted with that choice most won't have a clue what to choose. Can we say which ones are most relevant to a few average fishing situations?
 

PaulD

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There are 74 single handed fly lines for sale on the Scientific Angler's website


Confronted with that choice most won't have a clue what to choose. Can we say which ones are most relevant to a few average fishing situations?

Here's a table which shows the profile measurements of a number of lines - Snowbee XS, always very popular, middle of the road line, Opti Stillwater, quite often popular with instructors (well me!), a couple of 'technical' Rio lines - one for the presentation of nymphs and dries at distance the Light Line designed for slower 'traditional rods, and the Barrio GT125 . . .

Picture1.png
Here's what the providers say about the Opti, Rios and the Barrio lines . . .

The Opti Stillwater is designed for medium sized streams or lake fishing. The taper enables both short and long casts with long leaders and is designed to set the fly down with precision at distance.

RIO’s Elite Technical Trout line features a long, fine front taper for the lightest of presentations and delicacy and is the ideal choice of line when fishing dry flies, nymphs, soft hackles and emergers to tricky eaters at distance. The line has a long head and back taper to increase loop control when carrying long lengths, and for making precise casts to rising fish, while the weight distribution makes it easy to turn over long leaders for technical feeders at range.

RIO’s LightLine has been designed to load slower, more traditional action fly rods such as bamboo, glass and the more “Classic” flexing graphite rods. Built to precisely match the industry line standards, this line will not overload such rods – even at longer range. The weight distribution and short front taper ensures the line loads at close range, making it ideal for fishing on smaller creeks and streams.

The Barrio GT125 fly line offers superb presentation, line control and stability in the air. The finely balanced 73 ft head helps us to achieve sweet presentation at pretty much any distance and simply excels with long, smooth casting strokes. Our relatively short belly and front taper produces a line that will load a rod well at short range for off the tip casts, yet our extended rear taper allows huge lengths of line to be aerialised under control for long distance casts.


What do we learn from the producer's claims and the profile measurements?
 
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