The Rod-centric Approach (I)


This is the first article of a series devoted to Spey casting mechanics. A work in progress.

Spey vs. Overhead: the fundamental difference

On an overhead backcast the rod unbends, a loop is formed and the caster waits till the line gets straight —slack line during the casting stroke isn’t a good idea—, so on the following forward cast the rod tip starts pulling on the whole length of line and propelling it forward all at once. On the contrary, with any cast of the roll family our line is folded in two at the start of the delivery cast —with part of the fly leg of the D-loop never turning into rod leg before the forward casting stroke is finished. This means that on the delivery cast the rod tip is impulsing toward the target part of the line only, the rest of the line is just a passenger detracting energy from the section put in motion during the casting stroke proper. A significant difference indeed, with very important —and, at times, overlooked— implications.

The rod-centric approach

Following the current explanation, that folded line configuration —what we know as D-loop—seems not to influence the resulting cast that much, for, as they say, “the anchor provides the resistance against which to load the rod”, and getting the rod properly “loaded” is what we need. That is, the focus is on the rod and its “load”. It sounds right… the only problem is that Spey casting mechanics doesn’t work in that way. A simple casting experiment shows how, for the same casting stroke, a folded line configuration falls short of the target while a straight line reaches it.

It isn’t that rod bend is not important in fly casting —as anyone who has ever cast with a broomstick could testify— but rod load is a given, a byproduct of the force you apply to the rod with your casting stroke, and you don’t need to think about it more than you think about —let’s say— the force of gravity: both will take care of themselves,  you just have to adjust things accordingly.

First of all, one fundamental problem with the rod-centric model is that nobody knows what a proper rod load is for a given cast; I have never met anybody able to look at the bend in a rod during a casting stroke and tell if it is a proper load or not. Not only different rods will show different amounts of bend for the same cast, even every angler can get different amounts of rod bend for the same cast and casting distance, depending on their individual styles.

Last but not least, the other fundamental problem is that the anchor in any cast of the roll family doesn’t load the rod; it can not do it!

I know that the statement above goes against the official view, so it is time to take a much deeper look at this heresy.

Anchor and Loading

To judge how the anchor affects a roll cast nothing better than casting on a super-slippery surface, and that is exactly what the following video shows: a short indoors rod with a line and leader made of macrame and wool, used to perform a roll cast on a tiled floor.

One consideration first: I have been told on several occasions that the technique shown for that roll cast is very deficient. I don’t consider myself to be a great caster —nor this video was intended as an example of how to make a roll cast— but if you try by yourself some roll casts on a surface like that one, you will see that a disproportionately long stroke is the only way of making a decent cast that reaches its target. That shows that the lack of anchor poses some problems.

Here is master caster Bernd Ziesche making a roll cast in a similar scenario; the video includes some concise explanations of what is going on:

But that isn’t a real scenario! —Some instructors argue. Of course it isn’t, that is what makes it so illustrative! The goal of the experiment was to check what happens to the rod when the friction between the line and the surface it is on is almost non-existent.

Another view of the first experiment with the practice rod and line:

The key issue here is to notice that the end of the leader (that red-coloured piece of wool) doesn’t start moving till the very end of the casting stroke, with most of its backwards slipping happening after the stroke is finished. That is, when we apply force to the rod the anchor is holding its position, even on a friction-free surface; something really strange if we assume that the rod is pulling on that anchor, isn’t it?

And finally a variation on the same theme, showing graphically the difference between a straight line and a folded one:

The experiment above shows a length of bead chain. Part of the chain is hanging from the table edge; the rest of the chain lying on the table exerts enough force (due to its weight plus some —low— friction between each bead and the table) to prevent the haging part of the chain from falling to the floor. That is, the force exerted by the hanging piece of chain is balanced by the force exerted by the piece of chain on the table.

But, what happens if we fold in two that piece of chain on the table? That the force exerted by the hanging beads isn’t balanced anymore, so they now fall to the floor. The reason? The piece of chain going from the apex of the “V” up to the end lying on the table isn’t pulling on the hanging chain anymore.

Now imagine that this “V” is the V-loop of a Spey cast, which part of the V-loop pulls on the rod (therefore bending it) and which part doesn’t?

In the second part of this article we will address why and how a fly rod gets bent.

2 comments on “The Rod-centric Approach (I)

  1. Eugene Geppert says:

    Let me try to summarize and have you correct any mistakes. The 3 purposes of an anchor in a roll cast:
    Anchor reduces the energy lost by moving the fly leg backwards.
    Anchor reduces the momentum lost (momentum spent in a backwards direction) for the cast (needs the momentum for the forward direction).
    Anchor reduces the back displacement of the fly from its starting position; this lengthens the distance to the target.
    Gene Geppert


  2. Aitor says:

    Yes, that is the idea.
    By holding in place, the anchor avoids snagging the fly in the shrub behind the angler.
    Also, if the anchor doesn’t hold and slip backwards it wastes energy because it doesn’t move by itself: part of the energy needed for the delivery cast is used in moving the fly leg of the D-loop in the opposite direction.
    More energy is wasted in changing the direction of the moving fly leg od the D-loop.
    Finally, after slipping the fly is farther away from the target, so now it takes more energy to send it there.

    Anyway there will be a whole article on the anchor and its nuances.


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