Why is a Jump Roll More Efficient than a Static One?

That is a rather usual question and also a very interesting one. It has been asked to me again recently via the internet by a couple of fellow casting instructors. Let’s go for it.

Let’s take a look first at the Roll vs. Overhead video used in a previous article:

I will describe the scenario:
Just one rod rigged with two lines: Royal Wulff #7 and Rio Tournament #6.
The TT has the ideal taper for roll casting; the Rio is designed for long casts overhead.
The Rio is unrolled behind the caster; the TT set in a roll cast configuration with its leader anchored by means of a screwdriver stuck in the ground (is there a more solid anchor than planet Earth itself? If there is let me know).

In this way the very same casting stroke applies force to both lines. What the video shows, however, is that the overhead line reaches its target whereas the rolled one falls short. It is an interesting experiment that any caster can try by himself (just in case somebody doubts of the result).
Anyway the result is that, if you use a stroke with the amount of energy needed for the overhead line just to straighten, the roll cast line falls short of the target. Always. Why?

I have said that the very same casting stroke applies force to both lines simultaneously, but is it the same amount of force for both? No, it isn’t.
What our stroke is doing is applying the same acceleration to the rod, and the rod to both lines, but the length of line actually accelerated in one case is much longer than in the other: we accelerate the whole length of the overhead line whereas only a short piece of the roll line is subjected to acceleration.

Do you remember the basic formula of Force?
F = m.a.
For a refresher this is a nice and easy source Force

Acceleration is the same for both lines but mass isn’t. So the force we apply to the roll cast line is much less than that we apply to the overhead line. For the same, identical, casting stroke getting the same distance with much less force sounds impossible, right?

If you prefer we can address the problem from the standpoint of Energy.
By applying force to the lines over a given distance we are doing Work on them. Do you remember the formula for Work?
W = F.d
For a refresher this is a nice and easy source Work

The work done on an object amounts to the energy transferred to it; that is, more Work = more Energy transferred.
But we have already discovered that the roll line has been subjected to less force than the overhead one; less force amounts to less work done on the roll line and, consequently, less energy in it.
How do you expect to get the same distance with less energy?

So what we have is that the casting stroke that works for an overhead cast isn’t good for a roll cast. By the same token the stroke good for a jump roll isn’t enough for a static roll.

Some may say that, after all, that rod load shown in the video is just enough for propelling one line but not both. Another of the blindfolds that the casting paradigm based in load puts over our eyes.
Yes, only one line is propelled all the way forward but, how is it that it is always the one with the longer piece of “live line”?

So, as a corollary, IMO we have to think in terms of how long is the piece of line I am accelerating directly to the target, and not of the mythical “load” and “anchor loading” or the impossibility of a “highly energized V loop”.

Addendum

The key to understand this issue lies in the fact that the rod in the video isn’t applying the same force to both lines, just the same acceleration. It seems that it isn’t easy to grasp so an additional (more graphic) example to clarify this is in order:

Let’s say I have a video showing three model railway coaches.
Two are connected together and laying on a straight rail. Parallel to them there is another rail with the third coach laying on it.

In the front part of both convoys we have a string, one string for each convoy.
At a given time the strings get taught and the two convoys start moving with exactly the same acceleration.

Since the track has a ruler alongside, by means of Tracker or any other application we are able of easily calculate the magnitude of that acceleration.

We also know the respective masses of each convoy: isn’t a surprise that mass A has a value X and mass B has a value of X/2.

By solving the F = m.a equation we get that the force applied to mass A is double the force applied to mass B. Right?

Well, after that first video I show you a second one with a general view of the scene. Now we can see that there is a guy pulling on both convoys at once by holding both strings in one hand.
So now, out of a sudden, we discover that he is applying the same force to both convoys? Not al all, the force exerted on each of them is different, one being exactly half the value of the other.

Some Food for Thought

The roll cast [uses] water tension to load the rod.

I have read statements like that so many times over the years that it doesn’t come as a surprise. However, finding it in a fly casting book recently published makes me wonder whether casting authors do actually study the abundant material already available on the subject, or just stick to the old doctrine just because “it has always been said…”

As a gentle prod to start thinking out of the box this slo-mo I shot years ago comes in handy. Take into account how the short and ultra slippery anchor starts sliding when the froward stroke is almost over.

If during the acceleration phase of the stroke the rod doesn’t pull on the anchor how is it that the anchor does pull on the rod to load it? 😯 😏

Roll Cast vs. Overhead Cast

The latest articles have been about tailing loop issues; that still is an ongoing project and I have a lot of video editing and writing ahead.
While I put some order in those ideas I decided that it was time for some new slo-mo stuff, so yesterday I called my friend Haritz to shot an experiment that has been round my head for a long time.

The simple exercise of making a roll cast on water shows us that, although we like to say that its forward stroke is like that of an overhead cast, in practice a roll cast isn’t as effortless as expected (you know the anchor loads the rod for the forward stroke of a roll cast and all of that). Of course the water grip on the line plays a big role in this, but what happens if we make a roll cast on grass so line “stick” is removed from the equation?

I will describe the scenario:
One rod rigged with two lines: Royal Wulff TT #7 and Rio Tournament #6.
The TT one has the ideal taper for roll casting; the Rio one is designed for long casts overhead.

The Rio line is unrolled behind the caster; the TT set in a roll cast configuration with its leader anchored by means of a screwdriver stuck in the ground (is there a more solid anchor than planet Earth itself?).

So what we have is a roll cast and an overhead cast performed by the very same casting stroke.

The result? Just judge by yourself, but it seems evident that a roll cast asks for a higher rod tip speed to reach the same distance, even on grass.

If you understand why yo have the indispensable foundation to crack the code of spey casting mechanics. But this is just the rehearsal of a more complex project focused in the spey stuff.

Enjoy it… if there is somebody out there crazy enough for enjoying this geeky stuff. 😃

A Little Exercise

As an attachment to the previous articles on tailing loops (here and here) now an exercise on diagnosing a common casting fault. You are a casting instructor and your student is getting a recurrent tailing tendency. I shot this clip yesterday, playing as student and instructor at the same time. After dozens of plays I still can’t say what the origin of the problem is, even seeing when it is produced (watching carefully you can see the slight rise of the rod tip and the subsequent wave in the line).

What I know is that I was playing with the haul, trying to release the line just at loop formation (wherever that is). That could have resulted in a premature end of the acceleration of the hauling hand and the immediate tip rise. But, honestly, I don’t know and find incredibly difficult to diagnose and cure this kind of things.

P.S. After half an hour I give up trying to make the video embedding work. The great mystery now is whether there is anything more user unfriendly than WordPress.

Mysterious Creature Rides Again

Tailing loops. So frequent and still so puzzling.

As I wrote on the first post in this series we already have a pretty good idea of how tails are formed; getting rid of them is another matter entirely. I truly admire the insights of instructors from yesterday: reaching the conclusion that tailing loops come from a concave tip path of the rod tip wouldn’t come easily, specially if we take into account that there wasn’t high speed video available at the time. Today’s technology effortlessly shows that, in fact, it is a dip/rise of the rod tip what creates the dreaded tail. And this evidence renews my admiration for the amazing observation skills of those pioneers of casting studies, for although that dip/rise is somewhat a “concave path of the rod tip” it has nothing to do with those big bowl shaped tip paths so many drawings depict. For years those bowl shaped explanations were to me as perplexing as the tailing loops themselves: however much I looked whenever I saw a tail in someone’s casting I couldn’t see that big concave path everybody was writing about. Not even on the casting videos available. Reality is much much more subtle, so subtle that seeing with the naked eye the expected anomaly in the tip path -even knowing what to look for- is really hard. Here we have a tailing loop in full glory. It is played at a slower pace than real speed. The tail could be used to illustrate a casting handbook; can you see the “bowled rod tip” anywhere?: Tailing loop backcast a bit slower than real Better to use a gif at 100 frames per second, that is one third of the actual speed: Tailing loop backcast slow Observe how even at a pace three times slower than reality we just can catch a glimpse of some anomaly in the tip path. So let’s use a visual aid to see what is exactly happening with the rod tip: Tailing loop path This has cleared things up a little bit. Mainly two things come to my mind. First is that to get a tailing loop, even a huge one like that shown above, you only need to mess up a relatively short piece of the casting stroke. Second is a consequence of the previous observation and my main point so far: that this problem is so recurring due to the fact that a very small error, for just an instant, results in a surprinsingly big effect. It isn’t easy to feel, and then correct, things that happen in an instant, is it? It isn’t easy to detect for the caster himself nor for anyone else. The tailing loop depicted above is really huge. Let’s watch carefully another good one of more moderate size. Can you detect where in the stroke does the error happens even in slow motion? I can’t. The only way is playing the original video frame by frame to discover a veeery subtle dip and rise of the rod tip: Tailing loop backcast small tail Dip/Rise of the rod tip. It is worth to emphasize the “Rise” part since that motion is key in the formation of the transverse wave in the fly leg that we commonly call tailing loop. But that, together with some considerations about what is the ultimate cause of tails, is the stuff for a next article. P.S. The tailing loops shown here are real ones, nothing staged for the camera but involuntarily produced. The caster is a really fine one who drove from 400 km away for a course to improve his technique (I felt flattered and, at the same time, worried: would I deliver as expected?) His hauled casts were really nice. Then I took the camera and asked him to cast with the rod hand only. Removing the haul wreaks havoc with line control, but it is a fantastic exercise to educate our rod hand.

Distance casting? What for?

It is useless, most of the fish are caught within 12 meters. I have lost count of the number of times I have read and heard that kind of statement. Being a 99.9 % dry fly fisher myself I, almost, agree. There is a lot of truth in that reasoning. Anyway, if we don’t catch as many fish further than 12 meters away it could also be because we don’t cast to them, couldn’t it? Admittedly getting a dead drift with a long cast is some sort of mission impossible, although there are nymphing techniques for which distance isn’t a problem: if there is a fish lie out there… out there my nymph goes. There is another type of very special nymphing that asks for being able to cast as long as possible: nymphing for sea trout. Are you kidding? Sea trout on nymphs? Yes, big sea run brown brown trout on small nymphs. Only in Southern Patagonia I must add. For instance on Río Gallegos. Size #10 nymphs, like that in the following pic: Rubber legs

I will commit to training more specifically for distance with the double handed rod before traveling to Río Gallegos again. Not all the lies are very far away (although some of them ask for 30+ meters casts) the real problem is the relentless wind; if it wasn’t so cold one would say it comes directly from hell. Here is the result of a sideways breeze (an a mild one by the river standards) on a cast with a 500 grains skagit head (correction from César -the caster himself: isn’t a skagit but a Rage Compact, something like an embrutished Windcutter :-):Wind-1

Sometimes frustration is a word that falls short of explaining some feelings. I will never forget what Loro, our guide, told us the last day on the river: I have guided people who after a couple of hours fishing thrown the rod away and sat angrily on the bank. So I want to thank you for understanding how things are here. Fortunately great prizes await those who persevere:

Yes, definitely distance casting practice isn’t a strange proposition.

Mysterious Creature

Mysterious creature

Tailing loops have the aura of a mysterious creature. Currently we know pretty well how they are formed but, at the same time, we can’t help to surprise ourselves when we get a tail now and then, no matter how experienced we are.

When casting for perfect loop control I will immediately detect any error in the stroke, my hand will easily feel any deviation from its intended straight line trajectory. The view of the fly leg getting out of plane in relation to the rod leg at the latest stages of the loop life does nothing but confirm what I already knew before stopping the rod: that I had messed up the stroke tracing.

Next cast I drive the rod butt straight but fail in accelerating it progressively. Now, though, I am only conscious of my fault when the dreaded tailing loop appears in the line; I don’t feel any clue in my hand. The mystery lies in the fact that the most subtle error in force application may result in a noticeable tail. An error as subtle that we can’t even feel it. The cast shown below is a good example of that.

tailing fast

What’s is the nature of that error in applying force? Just a spike in acceleration somewhere in the middle of the stroke. If the rate of acceleration decreases before reaching the end of the stroke the tip of the rod rises over its previous path; it is that rising what produces the transverse wave that we call tailing loop. Nothing mysterious but somewhat hard to grasp for some casters.

The main issue contributing to this confusion is the lack of differentiation between the concepts of velocity and acceleration and their respective roles in rod loading.

High rod speed doesn’t necessarily means big rod load. Load is a consequence of force, and force isn’t related to speed but to the rate of change of that speed, that is, to acceleration. Let’s take a simple view to that.

Let’s imagine that, at a given instant during the stroke, we have a rod butt speed value of 6 units, and in the previous instant the speed value was also 6 units. Rod butt speed is constant, no acceleration.

On another cast at a given instant the rod butt speed is just 5 units and in the previous instant the speed was 4 units. It has increased its speed from 4 to 5 units, that is, it has accelerated during that period time.

So we have a cast with a rod butt speed of 6 units against a cast with a rod butt speed of 5 units. Guess what? At that point in time the cast with the slower rod speed will show a bigger rod load!

This is a somewhat simplistic approach since there are other aspects at play which affect rod loading, such as air drag and angle between line and rod butt, but it is accurate enough to illustrate what we are dealing with.

We also know that any premature unloading will make the tip rise over its previous path creating the wave which will evolve into a tail. For the rod to unload the force applied to it must decrease. And here comes the fundamental part to understand this issue:
We don’t need to stop the rod to unload it; we don’t even need to decrease the speed applied to the rod for it to experiment some unloading!

Let’s imagine a casting stroke whose speed increases progressively. The rod butt speed profile measured at successive instants could be like this:

2, 4, 6, 8

This shows that the speed is increasing in a progressive way, accelerating at a rate of 2 units of speed per unit of time.

But then we measure the rod butt speed at the next two instants and find that its progression has changed:

2, 4, 6, 8, 9, 10

Speed continues increasing but acceleration has decreased from 2 units of speed per unit of time to only 1.

Remember that force is directly proportional to acceleration so a decrease in acceleration equals a decrease in force: the rod unloads correspondingly.

This is what has been traditionally called non-smooth, non-progressive or erratic acceleration of the rod. This is what gets our tailing loops flowing. And, IMHO, this is the reason why tailing loop formation is so subtle and difficult to feel.

One more apparent mystery with tails: when made on purpose even a casual glance to high speed video clearly shows that their alleged cause very rarely matches the real one. Even with pro casters. This leads to the idea that those long lists of tail-producing problems are just part of the story; they aren’t causes of tails by themselves, they just might be conducive to tailing loops… if you aren’t good enough at force application.

Tails, so easy to make when you don’t control and so hard to purposefully produce when you have refined your skills! So difficult in fact that even terrible timing or creeping usually fail to get the expected bad result when our force application is spot on.

In practice, the only real cause of tailing loops is a faulty acceleration, or a casting angle too narrow to accommodate the bend in the rod. In my experience the latter is much more common in casting instructors demos than in real life.

Now let’s make some analysis of the cast shown here.

Obvious thing number one: the forward cast starts toooo soon.

If we don’t wait for the line to straighten we are walking in dangerous terrain: we are not necessarily getting a tailing loop but we are conjuring it up.

So when the line straightens while the forward stroke is in progress the weight of the whole line shocks the rod and produces the tail, right?

Well, no, that is an explanation from the times when casters didn’t have the tools to check what is actually happening. As the gif above shows the hint of a wave in the line which will turn into a tail appears way before the backcast gets straight.

What makes a rushed timing more prone to tailing loops is much more subtle.

The cast shown here, with that early start of the stroke, accelerates just part of the line. By the time the loop is formed there is still line getting incorporated to the forward cast adding more weight to the launched line. This obviously decreases line speed. So to compensate for that lost line speed the bad timed cast must launch the line with a higher speed than in the case of a proper cast with the line fully straightened back. For the same stroke length and angle that implies necessarily a higher acceleration. In layman’s terms you must cast “faster”, and fast motion and control don’t come along very well. Conversely, going “slow” and smoothly increasing speed are a perfect matching pair.

Obvious thing number two: lack of hauling on the forward cast.

What helps enormously in getting control of the rod hand is… the line hand. Let’s get a little deeper into this.

To send the line and fly to a given distance we need to propel it with the required minimum speed. We can get that speed by the use of the rod hand only, or, by means of a haul, we can add extra speed to the line making the task of the rod hand easier: it doesn’t need to apply the same rate of acceleration, going “slower” with the rod hand is now enough to get the necessary line speed to reach the target. And by going “slow” it is much easier to get the proper progressive acceleration we are looking for.

In my view an efficient haul could have avoided the tailing loop even with the fault in timing present.

What are your views?