Running line - the thinner the better?

[Mangrove Cuckoo]

So, imagine a standard WF flyline with a head and a running line. Now imagine casting it. There are many ways to “carry” the line, but to simplify it down to two basic scenarios: you could carry with some of the head somewhere within the rod tip guide, or you can carry the line beyond the head and have only the running line in the rod guides.

The length of the head plays a big part, at least in my experience. I have found that I much prefer to carry with the head just around the rod tip. There is a sweet spot of a number of feet, but outside that sweet spot, either way, and things go bad.

I think we all know that having the head too far out, and trying to cast with too much overhang, is a problem. Agree? (Nevermind Lasse - I expect you can carry with any length of overhang)

What I want to ask about is the opposite: how much is too much head inside the rod guides. What goes wrong and why does it work poorly?

I had been having a problem, a fishing one, and it might have something to do with this question. Many lines that I have gravitated toward have long(ish) heads. Fifty feet or more. I have grown to like long heads for casting - fun casting - as in casting some type of dummy fly in a field, for practice and/or just enjoyment. So, I have been choosing similar lines for fishing.

And, over the last few years, I have been finding a problem, which I was blaming on the line manufacturers or poor line maintenance on my part.

The problem presented itself like this: I would attempt to make a long cast, not competition long, fishing long. But, as the cast sailed away something would cause the loop to turn over earlier than I wanted, which would kick the fly over, and truncate the distance I was hoping for.

I first noticed it with an intermediate sink line. It had a long(ish) head and a very distinct running section of a different color. I began to realize that the problem presented itself when the back of the flyline head completed its journey through the guides, but then the running line, which I expected to sail through much easier, would seem to experience extra friction.

The head was in the guides because I was “blind” fishing and stripping the fly back much closer to me than the long(ish) head and leader. I first blamed the line. Somehow, I thought, the line laying on the deck was getting fouled… so that was causing the extra friction. But I found that to be wrong! If I just false cast and worked the line out to where no or very little of the head was in the guides, the cast would not kick and fall short.

Part of that problem was that I was casting a pretty heavy single hand rod (11 wt) with a fly of substantial size and wind resistance, and on a sinking line. Working the fly back close to the “boat” to maximize the water I covered, lifting it, and then false casting that system to work the line back out to the sweet spot was a significant amount of work!

Then, one day when casting a much lighter combo (a 8wt I think) I discovered the same fault: the cast would kick over and crash much closer to me than I wanted. Once again I was using a line that had a long(ish) head. And the problem was showing up in the same scenario: some of the head in the guides was again the culprit. In this case I was casting much smaller flies to a shoreline, repeatedly. The first solution was simply to move out from the shore to be able to pick up and cast from around the sweet spot. The downside was my accuracy fell off with that distance. The simplest fix was to use a different line - one with only a 30 foot head. That way I could make accurate 50 to 60 foot presentations from a pick up that kept the head outside.

OK, so this is where it gets potentially weirder! Today I tried something on conventional tackle, a spinning rod, and got some very unexpected results. I humbly admit to sometimes using a spinning rod. I often take other anglers out fishing in a two man canoe, and I’m always in the back. The anglers in front get all the good fly shots, which is not a problem: as the host I enjoy the experience through them. But often there is a target location either flubbed by the angler, or just not taken, that I want to check out - so I’ll fire something in there with the spinner.

I’ve been using GSP technology line on my spinning reels for quite some time. It has many advantages, but one particular characteristic - very low stretch- has some negatives too. Especially when fishing for tarpon. If the fish jumps close by when you are not expecting it, or you are, say, seated in a canoe, and cannot bow. Even a relatively small tarpon’s jump can break GSP lines due to their lack of stretch. So, when I heard about some new technology monofilament line I thought I would try it. Beyond some possible forgiving stretch, the clear. not opaque, nature of mono may have some advantages too, in some places I fish. It might also be an interesting option for fly leaders?

So I bought 330 yards of the new mono, of the same breaking strength of the GSP line I use. But I didn’t feel like rewinding all of the almost new GSP back onto its spool to test a full spool of the new mono. Which is, of course, of significantly larger diameter than the GSP.

In a “what the heck” kind of experiment I just knotted about 30 feet of the mono on top of the GSP, tied on a tournament style casting plug, and went out to the field. I was hoping for the best but was really expecting the thicker mono would reduce my casting distance. I was hoping it would not reduce it too much. Extra distance is a supposed advantage of the thinner, limper, GSP line on a spinning rig.

So… what happened? The same thing that happens when flycasting and a thinner running line follows a thicker head! The cast would start out actually better than I hoped - but when the thinner GSP would start to come off the spool (and contact the first “stripping” guide), the cast would almost abort!

Watching closely, it looked like the GSP would come off the spool in loops that bunched up at the first guide, causing much more friction, and act almost like “feathering” the line, but much too strongly. So, instead of it sailing smoother (which I once again erroneously expected), the thinner GSP caused the casting distance to be significantly reduced.

My guess is that despite being thinner, in all of the above cases, the “running” line is also much limper, and therefore, somehow, creating extra friction?

I had always thought that the thinner running line, having less mass, would be easier to pull through the air. And having a thinner diameter, should also experience less friction in the guides. So it was a double advantage.

Or, am I missing something? Is there some sort of shock when the thicker head gets free of the friction in the guides?

This really has me scratching my head!

Any of you physics guys want to chime in with a more learned explanation?

[Graeme H]

I think I know what you're asking: why does a heavy head prematurely turn over when we cast with much of the head is still inside the rod?

If that's the question, the answer is related to momentum and how the rod leg is accelerated by the fly leg when shooting line.

I'll use an analogy to explain it. Imagine a truck running into a car from behind. When it hits, it loses a little momentum to the car (it slows a bit) and the car accelerates rapidly forward. The truck weighs a lot more than the car and both move forward.

That's like the heavy head of the line: it weighs more than the running line, so when it pulls the running line, both keep going forward.

Now consider a truck running into the back of another truck of similar mass. The rear truck loses all its speed because it has transferred its momentum into the front truck.

That's like having half the head outside the rod tip. The fly leg starts pulling line via the rod leg but that line is heavy and it can't be accelerated as we'd wish just from the pull of the fly leg. The tension we generate from the heavy fly leg is basically countered by the mass of the remaining head, and the momentum we'd normally see accelerating that running line is wasted on accelerating heavy line from the remaining head.

I hope that has addressed the question you're asking. Sorry if I got that wrong though ...

Cheers,
Graeme

(PS - On reading your post again, I have no answer for the GSP/Nylon question. I haven't come across that problem with my spin gear (and I always use some sort of monofilament as a leader on my GSP.) If I have problems with that, it's due to a poorly tied leader knot that has fouled in the guides as I cast.)

[Lasse Karlsson]

Oh, I do get into trouble with too much overhang



When shooting, thinner is better. More friction from thicker and heavier line, and turnover comes prematurely. This is also the case with runningline in water, and releasing too late.
The thick mono ties to what is called superline here ( been using it for 30 plus years in my spinfishing) is causing the same, when the line comes od the reel, the knot hits the guide and creates more friction momentarily,

Then theres the fishing aspects, and using 10 lbs gsp for a shootingline is a recipient for cut of fingers

Cheers
Lasse

[Paul Arden]

Hi Guy,

Part 2. Is this off a fixed spool reel? It might actually have to do with less friction which is why it bunches up, ie briefly trying to overtake the mono. This bunch then creates the extra friction. (?)

I can certainly imagine a similar thing occurring in Part 1. However I would think more likely the issue is that, with head inside the rod rings, the loop has initially started unrolling quicker as a result of the increased friction (compared to a running line only in the rings). Very similarly to holding on with a shooting head for fractionally too long. I wouldn’t be surprised if the rate of unrolling was the same as say a DT.

What happens when the head is past the rings must be quite interesting.

It’s very common to see running line (indeed any line) bunching up around the stripping guide on a normal distance cast.

Cheers, Paul

[Mangrove Cuckoo]

Thanks guys!

The idea of relative masses outside versus inside the rod tip makes sense... with flylines. That makes me wonder about which rear taper is the best for different applications.

I'm not sure about the spinning lines though, as in that case the largest mass is in the casting plug and completely outside. I guess it's the knot causing the problem.

Coincidentally, I tested the new Sage CORE saltwater rods this weekend. At first glance I thought the stripping guide was damaged. It is deliberately bent forward instead of perpendicular to the blank. I guess to better gather the line shooting up from the deck?

Thanks again.

[Paul Arden]

Hi Gary,

My thinking with mono and braid is that it is simply scaled down. I don’t think the phenomenon of line bunching at rings can be explained without it having mass/momentum.

Cheers, Paul

[James9118]

Hi Gary,

There are many factors that affect the turn-over speed of the loop and they're all interconnected. One thing I've experimented with is trying to alter the angular momentum in the loop during it's initial formation. Many people will tell you that the way to 'slow' the turnover with a WF line (and thus increase distance) is to cast with overhang - however I'm not sure the reasons this works is very well understood.

Angular momentum is effectively a measure of how much mass of line is rotating around the front of the loop at any given time. If the line in this portion of the loop is made up of the head then the angular momentum is high (relatively speaking), however if the front of the loop is made of running line, or shooting line in the case of a shooting head, then the angular momentum is low.

Now consider the transition from the thin to thick, or vice versa, as a cast progresses. In the case where the initial loop is formed with overhang, i.e. the running line forms the majority of the loop and thus the angular momentum is low, then when the thicker head enters the front of the loop, because of conservation of angular momentum, the turn-over slows down (more mass, but less rotational speed means angular momentum is unchanged). As such, we have the basis of why casting with overhang leads to the delayed rotation required for the longer shots.

This affect also plays into to design of lines. Think of the profile of the MED - here the designer wants to slow the turn-over hence they've built the line such that the mass entering the front of the loop is increasing for the majority of the cast. It also goes some way to explain why lines with short rear tapers start 'mis-behaving' as the overhang is increased before a line with a gradual taper does.

Unfortunately things are then complicated significantly by issues such as loop morph and tension being added to the rod leg from friction of the line in the rings etc. Pulling on the rod leg essentially applies a torque to the bottom of the loop front, thus increasing angular momentum and speeding up turn-over. As a slight aside, I spent quite some time casting shooting heads where I'd cut the shooting line just behind my hauling hand - hence once that bit of line was clear of the rod the loop was free to fly without any other influence - I'd recommend this test to anyone who's interested in this sort of thing. Anyway, I would suspect two things are happening in your cast - firstly with the head inside the tip ring then your initial loop has to be in a high angular momentum state. Secondly, because the fat bit of line is in the rings the friction is increased accordingly. Both these factors result in a loop that wants to turn over really quickly.

With regards to you fishing scenario - on my saltwater trips I fish with similarly heavy tackle with big flies on wire traces etc. My preference for any shot up to maybe ~65ft is to aerialise the amount required and drop it in without a shoot. Obviously you want to avoid flailing such heavy tackle about as much as possible - that's why prior to a trip I set up a similar leader to what I'll be using to practice with. I will really concentrate on making use of every opportunity to shoot line when starting with a short line i.e. a big slipped lift, shoot into the BC (this sounds like Paul's snakehead shot, I know), then a big shoot on the FC. I then repeat the shoot into the next BC at which point I should be ready to deliver - although I may have a third false cast if I want to check the distance.

Cheers, James

[Graeme H]

Okay, now that it seems to be sorted in terms of the conventional explanation of momentum in the line, here's another explanation that makes sense to me (and almost nobody else here). A word of warning though: People here don't like this explanation because I'm considering the loop to be a wave, so keep it to yourself Gary.

Adding tension to the line (via rod guides, holding the line with your line hand, lifting the tip, checking the shoot or via the relative masses discussed above) makes the loop travel through the medium more rapidly, so it reaches the leader sooner than we want it to. That is, it turns over too soon.

Transitions between thick and thin line are changes in the mass of the medium ("linear density"), altering the speed of the loop through the line for any given tension value. "Turn-over" (wave propagation speed) slows down or speeds up in these transitions, which is why the loop running through those rapid transitions in line thickness "misbehaves". (This is a fairly simple answer to the questions of why lots of overhang slows turnover and why loops "morph", even if it's not an acceptable solution for most people.)

Tension and linear density are the factors of the impedance of the medium, which is the property that allows the loop to travel through the line. Modifying either factor will change the speed of "turnover", or how quickly the loop travels along the string.

The upshot for us as the caster is that we can "force turnover" in a failing cast by pulling on the rod leg before the loop dies (adding tension), or at least, checking the shoot. In the other extreme, we can kill an under powered curve cast by dropping the rod tip at the required time (removing tension and stalling the loop's progress through the line.)

There are so many more features that arise from thinking this way, but I have covered them all before elsewhere.

Cheers,
Graeme

(Taking cover now as I'm going to be hounded again ... )