Anchor Loading the Rod?

 

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A fishing roll cast: look at the lack of tension in the fly leg of the D-loop

I was trying hard to follow exactly what I had been reading on all those books. The roll cast was an easy one —authors said— in fact easier than an overhead cast because you get rid of the backcast part. However, when practicing it my results were awful, to say the least.

A guy waving a rod in the middle of an urban park is like a priest on top of a mound of lime. Fortunately, the guy coming to me this time was a fly fisher.
—Are you trying a roll cast? It is easy, I use it everyday on the river.
—Show me, please!
… and the cast ended in a heap of line.
—I don’t know what happens, maybe it is your gear —he said.

Looking for an answer to that frustration; what I found was mostly something along these lines:
It’s best to practice this cast on water because the water creates the friction and drag necessary for a good roll cast. The friction of the water on the line in the roll cast helps load, (bend) the rod.

Yes! That corroborated what I had been studying so far! Rod and line were the equivalent of bow and arrow: the rod gets bent —loaded— and it propels the line when unloading.
This approach leads to a widespread conclusion: any action or thing contributing to rod loading —sometimes only in appearance— is good by itself, while most of the problems with failed casts have their source in an “insufficiently loaded” rod.
But this isn’t how a fly rod actually works —in fact this view is totally misleading when trying to explain a good bunch of casting phenomena— however, since the bow/arrow model is still the prevalent view in the casting scene, it is worth examining rod load in spey casting. So the present article comes as a complement of this one about bend when the anchor settles, and this other one on the effects of circling-up after the sweep.

The following video is the second most viewed one of my Vimeo channel, and probably one of the less well understood. Let’s analyze what that experiment shows. What I am using to make some roll casts is an Echo Micro Practice Rod, whose “line” consists of braided cotton cord with a short piece of red wool as the “leader”. A tiled floor makes for the perfect scenario for the experiment. Since when casting on water the anchor is said to be the main actor providing rod load, what happens to rod bend when we have no anchor at all?:

 

Another roll cast from a different point of view:

What is happening on those clips? We have a very slippery floor that allows the line lying on it to slip freely, with almost no resistance due to the very low friction provided by the polished surface. As the current view on anchor and rod load states, the water “grip” on the anchor provides the resistance against the rod is moving, putting a bend on it. The rod pulls on the anchor and the anchor reacts and pulls on the rod bending it. But is that what actually happens?

Let’s address the main factor to understand this issue: during the casting stroke tension on the fly leg of the D-loop is very very small, that is, the force exerted by the moving D-loop on the anchor is very small, so small in fact that the anchor on a tiled floor remains in place during the whole casting stroke. It is important to notice that the line starts slipping backward only when the casting stroke is finished; the turning D-loop is able of making the anchor slip only when it is very close to the line end, when its small force is exerted on a shorter piece of cord, whose small mass opposes much less resistance to the pulling.

A fly rod bends due to action/reaction: we apply force to rod and line and these react due to their inertia —a body that isn’t in motion wants to remain still and opposes itself to any force trying to put it in motion; inertia we call it—, trying to oppose that force. Since the rod is flexible it bends, gets “loaded”. But, as those videos above show, if the fly rod pulling on the rod leg of the D-loop is unable of moving that super slippery anchor it is because it isn’t actually pulling on it, and if the rod doesn’t pull on the anchor the anchor doesn’t pull on the rod!; no pulling, no load!

And what about the bend in the rod on those slippy anchor casts? As we can see the rod gets loaded even without the supposed effect of the anchor. If it isn’t the anchor, what is it that provides that load? Just action/reaction, as explained above. When the stroke ends the rod has been pulling only on the piece of line that forms the rod leg of the D-loop, but not on the rest, that is, not on the piece of line lying on the floor. So that rod bend comes from the reaction of the rod itself and from the reaction of the rod leg of the D-loop only. That length of line that the caster has impulsed during his casting stroke is what I call live line, as opposed to the dead line which forms the fly leg of the D-loop; this dead line contributes nothing to our cast, it is just a passenger, a payload. But this is an interesting aspect that will be analyzed in another article.

OK! —you say —but that is just an experiment, what happens in a real cast?

As shown on this clip, on water we face the same phenomenon: the anchor slips after the casting stroke is finished:

The following picture was shot in a real fishing situation. It shows that even with a water anchor, tension in the fly leg of the D-loop is so low that that piece of line isn’t tight at all:

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Another clip showing how small is the force exerted by the rod leg on the fly leg:

So, if the anchor’s function isn’t rod loading, what is its role? The following video addresses this. Take notice of the instant in which the anchor starts sliding backward and its effect on the front loop speed and shape:

Conclusion? Don’t think of rod load, just concentrate in as long a live line as possible, with it, V-loop and anchor pointing in the direction of the target. And consider rod load just as a by-product of a well executed casting stroke.

Sweep, Loading… Unloading II

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In the first article of this series we studied how the setting of a V-loop doesn’t put any load in the rod. The momentum of the line travelling backward is transferred to the water, without affecting the rod tip. In many spey casting technical works we find another purported source for that mythical rod pre-loading: the rod motion from the tilted sideways position at the end of the sweep into the more vertical position suitable for starting the forward cast, a maneouver also known as circling-up. A quote from the internet about this circling up and its consequences puts things in perspective:

It is intended to transfer the rodloading created during the Sweep, on through to the Forward Cast, in a continuous, uninterrupted fashion… no stopping of the rod, no load-unload-load action… thereby maintaining continuous loading of the rod.

As H.G. Wells wrote: It sounds plausible enough tonight, but wait until tomorrow.

Will tomorrow be able of invalidating plain logic?

As we have seen in the first part of this study rod bend comes from a force. After the sweep is finished the line moves on its own backward; the rod pulls on the line making it turn and a loop is formed.

– Well, for that to happen the rod has to exert a force on the line, and the line exerts the same force -action/reaction- on the rod in the opposite direction, right?

– Yes, of course.

– So the rod gets loaded, right?

– No, slo-mo says it doesn’t and so does physics.

Let’s take a look to the equation for force:

F = m.a

What this equation states is that force is directly proportional to mass (weight in layman’s terms) and acceleration (change in velocity). The bigger the mass the bigger the force needed to accelerate it; the bigger the acceleration the bigger the force applied. So for a force to be increased we could increase m, a or both.

So what happens to the mass of the line and its acceleration -and consequently to force and then rod load- in those two phases of spey casting known as sweep and circling-up?

During the sweep we are applying force to the whole length of line at play in order to form a loop; during circling-up we exert force only on the short piece of line which is actually turning around in the loop front, the part of the line changing direction but not on the rest of it. During the sweep we are pulling on a much bigger mass.

What about acceleration? During the sweep we have to accelerate the line significantly to form a loop; when circling-up the rod is not accelerating anymore, for the caster moves it to the key position leisurely, without the intention of applying any significant force. During circling-up we are pulling with much less acceleration.

The logical conclusion? The force bending the rod on the sweep is comparatively big and decreases hugely when the sweep ends. In fact the force exerted on the rod by the line during circling-up is so low that the amount of bend left is irrelevant. Some video to clarify things:

 

The following pictures correspond to three frames taken from the video above: they show both the difference in the mass the rod is pulling on, and the difference in rod bend between the sweep and the circling up.

whole-line

The sweep applies significant force to the whole line. The rod is bent.

rsp

End of the sweep. No force applied to the rod or the line. Note how the line has lost tension and the rod is straight.

loop-front

An instant during circling-up. The rod is pulling only on that piece of line inside the red circumference, so there is no appreciable bend in it.

 

 

More video:

 

Is it that important to be aware of these intricacies? It is, in my opinion, if only for one reason: if you train or fish focusing on getting some impossible pre-load, you won’t be paying attention to the things actually defining spey casting efficency, namely: minimum anchor, maximum live line in the V-loop, all that aligned with the target and as close to the forward rod tip trajectory as possible.

Sweep, Loading… Unloading I

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Always shrouded in the mist of mystery, when popular casting mechanics focuses on spey issues it seems to enter the realms of magic.
It doesn’t help that the various styles of spey casting seem to compete in presenting their respective approaches as if they were different techniques, instead of just adaptions to some particular conditions.
Fortunately spey is spey, and physics is physics, and the latter governs the phenomena involved in the art of throwing a line with a pole in exactly the same way, whatever the brand, length or taper of your rod and line, and the waters and fish you are after, be it in Scandinavia or in the Pacific North West.

One concept is common to some of those schools, though: that efficiency in spey casting lies, in good part, in some kind of pre-load of the rod prior to the start of the forward cast.

An excerpt from a highly-regarded book will clarify this point:

With the fly/leader anchored to the water surface, the momentum of the forming “V” loop reloads the rod 180 degrees as a reaction.

So when the anchor touches down and the V-loop forms the rod gets automatically loaded. Apparently as the line is traveling backwards it will pull on the rod tip forcing it to bend. Pure logic, isn’t it?

The problem is that physics has the annoying habit of defying what at first sight looks like common sense. The good news is that high speed cameras, and a basic knowledge of Newton laws, help to open a more clear window into reality.
So in order to shed some light on this issue I did set up the following scenario:

  • Scott STS 7’6”#3 rod rigged with a #8 Barrio SLX line (equivalent to an AFFTA #10 one).
  • Line configuration in front of the caster similar to a perry poke with my right foot stepping on the line tip.
  • A sweep to set the V-loop.
  • Without a pause the rod is lifted up to the starting position for the forward cast in a continuous motion, and is stopped there.

Here you are:

An analysis of the casting sequence shown above is in order:

I start the sweep by accelerating the rod butt; I finish the sweep by decelerating the rod butt; as soon as the rod butt speed decreases, rod unloading starts.
Take notice that when I reposition the rod for the forward cast there is no load left in the rod.
After that the V-loop is fully formed and the line gets tight. That tension in the line loads the rod, right? Well, no, as shown by the video above the tight V-loop against the rod doesn’t put a bend on it.
Does it sound strange? Well, in fact basic physics tells us that it couldn’t be any other way. To understand this we have to look at the reason for rod bending, that is, force.

The sweep applies force to the rod, and the rod applies force to the line. Newton taught us that forces always come in pairs, it is what we know as action/reaction. So the rod applies a force to the line and the line reacts applying the same force to the rod in the opposite direction. Flexibility makes the rest.

The caster finishes the sweep by ceasing applying force; no force, no bend; the rod unloads itself. It is capital to take into account that the rod doesn’t need to be completely still to unload, that process happens before: as soon as the caster decreases rod butt velocity the rod unloads. Motion doesn’t necessarily mean force, only accelerated motion does mean force; a decreasing rod butt velocity means that it is not being accelerated anymore, and when acceleration disappears force disappears as well. In summary, a complete stop is not needed for the rod to unload.
At some point in the unbending process the line overtakes the rod tip, and the rod tip pulls on the line forcing it to turn around: a loop is born.

Back to the line in course of crashing against the water: it gets anchored and gets stopped.

What has stopped it? The water (in the case of the video above my foot).

Where does the fly leg momentum go? Obviously to the water, so that force of the crashing anchor is applied to the water, not to the rod!

An old slow motion video showing rod load when anchoring on water:

And another one:

But don’t take my word for it. A very easy experiment for you:

Rig a rod with line and leader. Lay the line in a perry poke configuration like that in the video. Take the end of the leader between your fingers. Make a sweep. Do you feel anything in your rod hand? Do you see any sudden loading? Where do you feel the tug of the line when it gets tight?

Focus Shift

Nowhere in the world of sending a fly out there with a line you can find rod load being more glorified than in the spey casting scene. Everything seems to gravitate around that. If the cast is good it is because the rod was properly loaded. If it went wrong… well, sure it is due to the rod not having enough load or unloading prematurely.

Sometimes it is possible to get more clues from the analysis of a bad cast than from a perfect one. That is the case with the casts depicted here. The video and pics show a pretty common occurrence that will be used to point out some keys of spey casting mechanics. Take them just as a brief introduction to following articles which will get deeper into that subject (slow motion clips and some not-that-heavy-physics included).

The scenario is the forward cast of a spey characterized by some kind of V-Loop that we will call 7-Loop (thanks to Simon Gawesworth). An extreme 7 for that matter.

Let’s say that you set a nice V-Loop, make the cast and present the fly on target.
On the next cast you manage to get a 7-Loop and the fly falls short of the target on top of a heap of line and leader. That is just one of the possible outcomes of that loop configuration -as it is a fat loop, a tailing loop or even the three of them combined-  if the caster doesn’t compensate his stroke to adapt. Even if he modifies his stroke successfully the 7-Loop is still inefficient due to the amount of wasted energy.

The following gif made from a couple of pics from a still camera will shed some additional light.

7loop-problems

We could look for an explanation to the inefficiency of that 7-Loop in the gif above in the usual way, basing our analysis in the behaviour showed by the rod. It would go along the following lines.

What happened to this cast?

  • Hmm, probably the rod didn’t get loaded… but I see a pretty good bend, though!
  • However, is that a properly loaded rod? Who knows? I, for one, don’t have a clue nor have met anybody capable of quantifying whether a given load is enough for a given cast or not. If only because you can make a cast to the same distance with the same rod and line with rather different loads.
  • Well -you say to yourself- it could be that the rod got unloaded prematurely due to the anchor slipping… but the loop’s rod leg looks pretty straight, whereas the rising tip of an early unloading would have set a wave in it!
    As shown here:

Hmm, we are not getting very far with that approach.

So let’s address the issue from a different standpoint, forgetting the rod and putting the accent in the line.

From the gif above we can quickly draw some visual clues:

  • A totally ineffective anchor due to the angle of attack.
    Only part of the leader is in contact with the water, moreover the angle at which the loop pulls on the anchor makes the latter specially prone to slipping. See how at the end of the stroke the apex of the loop still hasn’t moved forward due to the slipping anchor! In fact it moves a little bit backward! It is a perfect case of a loop propagating but not traveling (but that will be the subject of another article).
  • The amount of line in the rod leg of the 7-Loop.
    The length of line in the rod leg at the start of the stroke is very very short. The longer the piece of line we propel during the casting stroke (the “live line” so to speak) the more efficient the cast:

The reason for that inefficiency has already been covered in this previous article. You can also relate it to the case when we rush the forward stroke of an overhead cast and start it with the line still half its way backwards.

So, compared to a proper V-Loop configuration, for presenting the fly at the same distance a 7-Loop:

  • Will ask for a higher rod butt acceleration, as a way to give enough momentum to the comparatively shorter length of “live line” we propel during the stroke, to carry a comparatively longer length of “dead line”. That is the reason why the  “dead line” to “live line” ratio is key regarding efficiency: the longer the live line the better.
  • Anchor slipping wastes energy: the line moving backwards goes in the opposite direction of the target, and it doesn’t move by itself so it detracts from the energy needed to move the line forward.

Obviously the longer the cast the higher the impulse you need, which may result in a bigger load, but load is a byproduct of our force application to give the line enough momentum. It really isn’t our goal.

Given that the function of the casting stroke is to give enough velocity to the line in the right direction, it is better then to shift our focus from the rod -which says very little- to the line -which speaks volumes.