What? Delayed Rotation You Say?

We call casting stroke to the motion described by our arm and hand to propel our rod butt during the cast. In this way, we talk about back and forward casting strokes.
The casting stroke has two main characteristics:

  • It has to be an accelerated motion, that is, the speed of the rod butt should be increasing over time.
  • It is comprised of two different elements: translation and rotation.

Translation/Rotation

Taking the angle between the rod butt and the horizontal as a reference, we call translation to a motion that displaces the rod butt without changing that angle; that is, if the rod was horizontal at the start of the motion, translation moves the rod forward or backward keeping it horizontal.
On the other hand, we call rotation to a motion in which the angle between the rod and the horizontal is changing along the way.
In summary: in a translational motion the rod butt doesn’t turn, for that you use a rotational motion.
What to do for putting to work these two elements for a good casting stroke? Well, let’s first take a look to the function of the casting stroke itself.

Giving speed to the line

In contrast to spinning technique, in fly casting what we propel isn’t the lure but the line. To send our fly to the target we must give our line some velocity, which will have to be higher the farther away our target is (or the faster the headwind). The function of the fly rod is to give proper line speed to the line, by means of an efficient casting stroke. The most efficient casting stroke will be that which allow us to reach that line speed with minimum effort.

Rotation at the end

From an efficiency standpoint the best casting stroke is that which places rotation at its very end. At the start the rod is still and we begin the casting stroke by translating the rod butt, that is, displacing it without changing the angle it forms with the horizontal (or with our own forearm, which may be a clearer reference). When we are reaching, say, the final third of our casting stroke length, we rotate the rod, that is, we change the angle of the rod butt. This maneuver is called late rotation, delayed rotation, rotation at the end, or, simply, translation/rotation.
This casting stroke allows us to give speed to the line with minimum effort. We could represent it graphically like this (motion goes from left to right):

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The angle of the rod in relation to the horizontal doesn’t change up to reaching the last phase of translation. Notice that this late rotation isn’t isolated, it overlaps with the end of translation.

Training

Unfortunately, delaying rotation is a technical gesture that for some strange reason doesn’t come intuitively; quite the opposite, what seems to be more natural —at least with fly rod in hand, see the article linked above— is a casting stroke in which rotation is performed over the whole motion. So, to make this translation/rotation second nature we need to practice. In that regard, I like to train what I call the javelin throw. Obviously, it isn’t the kind of casting stroke we would use to present our fly at close or medium distances, but to make long casts (let’s remember that long cast/long stroke); anyway, it is an interesting exercise even if you are not particularly keen on long distance casting, for that long motion needs more time to be performed, and that extra time allows us to better focus on the differentiation between translation and rotation. This is the javelin throw:


Let’s visually analyze that “delaying rotation” issue.
The following video comprises 131 frames; I divided it into three periods of equal duration:

  • First period: from frame number 1 to number 44.
  • Second period: from frame number 44 to number 88.
  • Third period: from frame number 88 to 131.

Overimposed you can see the angles described by the rod butt during each of the phases:


The following frames are taken from the video above:

9B52B642-A8B1-4058-8F34-7056E84CAAF3
Start of the forward casting stroke
42901FE3-8E65-4D85-8155-8E887542351C
First period: the casting stoke angle gets open a bit
055ECFF5-B3DA-4AE3-8367-0A8F80826FC2
Second period: the rod butt Moves forward and rotates 9º in relation to its previous position
0D1C4EF0-0F16-49C7-9D35-861360EA6EFD
Last phase of the casting stroke: an additional 119 of rotation in relation to its previous position

As you can notice, most of the rotation (119º from a total of 128º) occurs during the last third of the casting stroke.


The following clip is a visual analysis of this translation/rotation concept on an actual distance cast by master Paul Arden:

Paul showing a perfect late rotation

In practice, for casts at usual river fishing short distances, leaving all rotation to the end is not really possible, there is an angle change to some extent. Anyway, late rotation is the ideal to focus on, in order to make good casts at any distance.

Versión en castellano

2 comments on “What? Delayed Rotation You Say?

  1. paracaddis says:

    I am looking at that cast by Paul and wondering is there any positive effect from the translation? It appears that the second phase of the double haul is “using up” the translation movement. Such that the forward translation is not moving the line but rather ,simply taking up the slack created by the haul.. What I mean is wouldn’t it be better for the hands to be close to one another before the commencement of forward translation? I have watched several times and can’t be sure, but the translation seems to be wasted in terms of moving the line forwards. ?

    Like

    • Aitor says:

      “I am looking at that cast by Paul and wondering is there any positive effect from the translation? It appears that the second phase of the double haul is “using up” the translation movement. Such that the forward translation is not moving the line but rather ,simply taking up the slack created by the haul.”
      Yes, it is known as “sliding”. As you have pointed out the “feeding back” of the haul counteracts the early phase of the translation so the latter can’t move the line forward nor increase line tension. So that approach which considers translation as a line tensioning maneuver gets invalidated.

      But that isn’t how translation works. Here lies the key (copy&paste from the article):
      “Notice that this late rotation isn’t isolated, it overlaps with the end of translation.”

      To understand the role of translation we have to use the Physics concept of Work. Work equals Kinetic energy, that is, line velocity. W = F.d.
      Force is applied mainly by rotation, translation adds distance. As per the formula above, the longer the distance over which a force is applied the higher the line speed.
      Graphically it would be like this:

      Rotation only:

      \/

      Rotation overlapped with translation:

      \ | /

      Notice how in the second case the rod tip is applying force to the line over a longer distance.

      Like

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