Evaluating the Haul

[Merlin]

Gordy
Here is the illustration for Lasse’s forward cast. In his case I find something like “3 r”, but had I chosen other points, maybe I would have been closer to 4.

Lasse FC haul vs line hand.JPG (35.25 KiB) Viewed 365 times

Below I illustrated the relationship between haul speed and hands separation speed (more precisely line hand to rod butt distance):

Paul vs Lasse FC.JPG (28.91 KiB) Viewed 365 times

Somehow surprisingly, there is a good correlation (1 to 1 nearly) for Paul’s FC. That is consistent with the “2 r” finding. If line hand follows a half circle path, the final haul distance should be “2 r”, but this is not a universal law, just a single case, a curiosity I would say.
In terms of comparison, peak haul velocity occurs some 15 ms before peak line hand velocity for Lasse in his forward cast, and there is no difference in timing for his back cast. We do not have a documented database to find anything but trends.

Merlin

[gordonjudd]

Below I illustrated the relationship between haul speed and hands separation speed

Merlin,
I too have found that the hand separation speed is a good proxy for the haul speed on a forward cast where the haul is in line with the rod.

What does that plot look like on a back cast where the stripper guide speed is more dominate?

Gordy

[Merlin]

It looks like that Gordy

Paul vs Henry BC.JPG (30.59 KiB) Viewed 326 times

Merlin

[Paul Arden]

Well, I like to be consistent

[Walter]

This may or may not be on topic, but based on the description of my hauling model from post 23 in this thread I've put together a simplistic model of the haul using a combination of translation and rotation of the hauling and rod hands. I just thought I would share some preliminary result. This is purely a physical model. I have the option of including some biomechanical considerations, such as adding multiple stages to each of the motions but I haven't given consideration at this point regarding the feasibility of the actual motions involved. If joints don't work that way that is an issue for future refinement of the model.

One of the things I can do with this model is to separate the translation and rotation of the rod and line hands into individual inputs. In this post I'll just show rotation of the rod hand only using a stationary line hand but changing the position of the line hand relative to the stripper guide for each stroke.

I am using a distance of 0.3 meters from stripper guide for each of these casting strokes. In each case the rod is rotated from 0 degrees (horizontal in my chosen reference frame) through 180 degrees to horizontal again. In each case I perform the cast/haul as I move the line hand from -.03 m from the rod hand to 0.3 m. At -.3 my line hand is located at the stripper guide. At 0 m my line hand and rod hand are together.

In the first series I use a constant angular velocity of 180 degrees/sec and rotate my rod hand about the wrist only (0 distance from rod hand to center of rotation from rod hand). The results are as follows:

Line hand at: -0.3, -0.2, -0.1, 0, 0.1, 0.2, 0.3 m
Haul Distance: 0.6, 0.4, 0.2, 0, -0.2, -0.4, -0.6 m
Min or max haul speed: 0.94, .62, .31, 0, -.31, -.62, -.94 m/s
Rod angle at max/min speed: 0, 49, 72, undefined, 110, 133, 180 degrees

In the next series I use a constant angular velocity of 180 degrees/sec and rotate my rod hand about the elbow (0.6 m distance stripper guide to elbow, and 0.3 from rod hand to center of rotation from rod hand). The assumption is that the stripper guide, rod hand and elbow are all in line on the X axis (probably not biomechanically correct) with the stripper guide located a X= -.3, rod hand at X = 0 and elbow at X = 0.3m. The results are as follows:

Line hand at: -0.3, -0.2, -0.1, 0, 0.1, 0.2, 0.3 m
Haul Distance: 1.2, 1, 0.8, 0.6, 0.4, 0.2, 0 m
Min or max haul speed: 1.9, 1.55, 1.25, .94, .62, .31, 0 m/s
Rod angle at max/min speed: 0, 34, 49, 61, 72, 81, undefined degrees

In the next series I use a constant angular acceleration of 180 degrees/sec/sec with initial angular speed of 0 and rotate my rod hand about the elbow (0.6 m distance stripper guide to elbow, and 0.3 from rod hand to center of rotation from rod hand). This is the same as the previous set but with constant angular acceleration rather than constant angular speed. The results are as follows:

Line hand at: -0.3, -0.2, -0.1, 0, 0.1, 0.2, 0.3 m
Haul Distance: 1.2, 1, 0.8, 0.6, 0.4, 0.2, 0 m
Min or max haul speed: 1.93, 1.74, 1.5, .1.2, .84, .44, 0 m/s
Rod angle at max/min speed: 75, 70, 80, 87, 92, 100, undefined degrees

[Walter]

Sort of on topic. Getting in to a bit of the biomechanics.

Carrying on with evaluating parts of the haul. This time I looked at the active haul (i.e. rod hand does not move but line hand does) only and compared hauling the same distance but using a circular hand path vs a straight path. In this case the rod is vertical. Distance from stripper guide to rod hand is 0.3 meters. Distance from line hand to elbow is 0.3 meters. Both hands start together. For the translation charts the line hand pulls straight down for 0.6 meters at a speed of 0.6 meters per second. In the rotation graphs the line hand starts and ends in the same position but rotates around the elbow for a 1 second period (-180 degrees per second constant angular speed). Start angle for the line hand to elbow is -90 degrees, i.e. the elbow is directly below the line hand at start and the end angle is -270 degrees (i.e. the line hand ends up 0.3 m directly below the elbow or 0.6 m below it's starting point).

Results are as follows:

Translation only, constant speed 0.6 m/s

. Maximum haul speed .6 m/s

Rotation only, constant angular speed 180 degrees/s. Maximum haul speed .94 m/s

[Walter]

Playing around with the model again. In this run the rod begins horizontally with distance from stripper guide to elbow (the center of rotation for the rod arm for this run) 0.6 m. The line hand start position is together with the rod hand. The rod rotates about the elbow at a constant rotation speed of 180 degrees/second. The line hand pulls straight down at a constant speed of 1 m/s. Total time of the run is 1 second.

The interesting thing with this run is that the hauling speed reaches peak speed at 0.24 seconds (rod has rotated 43 degrees) but it becomes negative at 0.85 seconds (rod has rotated 153 degrees).

active and passive haul.jpg (48.7 KiB) Viewed 150 times

[Walter]

Repeating the same run but adding translational movement to the rod hand moving it straight up (opposite direction of the line hand) at 1 m/s during the run gives the following results. This time peak hauling speed occurs at 0.21 seconds (rod has rotated 38 degrees) but does not become negative later in the run.

active and passive haul 2.jpg (52.78 KiB) Viewed 150 times

[George C]

Interesting stuff, Walter.
Thanks for posting it.
More food for thought regarding the role/importance of translation in a fly cast.

[Walter]

You are welcome George.

Here is another one with a similar set up. The difference this time is that the rotation of the rod is a uniform acceleration from 180 degrees to 0 degrees over the course of 1 second. Line hand movement is a constant speed of 1 m/s downward with no rod hand translation.

Peak hauling speed occurs at 0.52 seconds (rod has rotated 49 degrees). Negative hauling speed becomes even more pronounced.

active and passive haul 3.jpg (55.17 KiB) Viewed 82 times