Measuring the Haul

[Walter]

Carrying on from the topic "Defining Haul Distance and Speed" in the Flycasting forum.

We have a tentative definition of hauling distance as

movement of the line relative to the tip guide during the casting stroke.

Given that the guides are a fixed distance from each other (ignoring minor differences due to rod bend and assuming we don't have some sort of weird line stretch happening) we can also say that it's the movement of the line relative to any of the guides. If I pull a meter (3 feet) of line through the tip guide, then I'm also pulling a meter of line through the stripper guide. If I have at least one mark on my line, I can measure this distance fairly easily using video. With a second mark on the line, I can also compensate for error due to perspective/camera angle.

The question has come up whether this can also be measured by looking at the distance between the hauling/line hand and the stripper guide. In most cases the answer is yes but there are some issues to be aware of.

One issue is that there could be an extra level of complexity in perspective angle with regards to the direction the line hand moves. This is illustrated in this diagram:

In both cases the line hand has travelled one unit of distance from the stripper guide, and this can be measured in B but in C the haul appears to be zero length. When we look at hauling speed the issue can be even more complex because the line hand could be changing haul direction relative to the camera throughout the cast.

Another issue is that I can hold the line against the rod butt with my rod hand and let the line slide over my hauling hand instead of holding it firmly with my line hand. I will haul twice as far as the distance that my line hand moves relative to the stripper guide. I've drawn a picture to illustrate this:

You can see that I've moved my line hand one unit horizontally. Given the starting position of my line hand relative to the stripping guide this results in a change of distance between the line hand and stripper guide of 0.6 units of length but the total amount of line I will have pulled through the guides (i.e. actually haul distance) is 1.2 units.

I know holding the line against the cork with the rod hand isn't a common practice (I sometimes use it during pick up) when hauling but whenever the line is made to travel a path that isn't straight from the hauling hand to the stripper guide it can affect the measurement. Lasse posted a great video in the other thread, and you can see that at various times during his haul he actually pulls the line around his body making the breaking the straight-line path from line hand to stripper guide.

I hope Lasse won't mind if I also post that link here:

https://vimeo.com/26512805/description

[gordonjudd]

I can measure this distance fairly easily using video.

Walter,
"fairly easily" may be a simplification when the line has a curved path as shown in this frame grab of Lasse's video with the line marker.

How would you recommend that the arc distance in the line between the rod tip and line marker be measured other than taking 10 (or more) points along the line for each frame that you are digitizing to get an accurate arc length for each frame in the video?

tip2marker_distance.jpg (36.44 KiB) Viewed 360 times

As presently configured, Tracker does not have an arc length measurement option for curved line lengths so you would need to use another video analysis program to do the distance measurement required.

Gordy

[Walter]

Gordy,

Good question.

“Fairly easily” would apply to before loop formation.

Torsten mentioned using a zebra line but since displacement is vector quantity using a point closer to the fly would still have issues in this case.

One of things I want to look at is whether acceleration of the line occurs after loop formation and if the haul has value after loop formation begins. I’m beginning with the assumption that acceleration stops or is negligible after the start of loop formation but that is strictly an assumption at this point.

When we look at the frame grab you provided we can see that loop formation has started but the line hasn’t overtaken the rod tip yet. The circular path from the tip to the fly leg indicates there is is tension between the rod tip and fly leg but how much of this tension is contributing to accelerating the fly leg is tbd.

[John Waters]

Excellent question Gordy and response Walter. The answer will be important in any behind the shoulder vs. in front of the shoulder relative contribution to performance.

John

[Walter]

John,

Based on your knowledge of biomechanics, if I determine that the maximum speed of my line hand is some value, is changing the path of the line hand likely to affect that maximum value? I’ll use 5m/s as an example. If my line hand is moving purely translationally and the highest speed I can reach is 5 m/s is that maximum speed likely to change if I add a rotational component to its path? Would it increase, decrease or stay the same (approximately)?

My thoughts are that translating a body part such as the hand involves rotation of multiple joints which will result in slower speed than constraining ourselves to rotation around a single joint. Pure translation would be the lower limit vs pure rotation as the upper limit. Of course, when we put a lever in our hand we can see an obvious difference when we translate vs rotate but I’m thinking of the hand only. Jab vs cross…

Thanks

Walter

[John Waters]

Hi Walter,

Hand speed should always be the focus of fly distance casting and we have a lot of potential to capitalise on in that regard.
I could rabbit on forever about that but, yes I absolutely agree with you that if the translation of the hand is a result of cumulative rotational speed of the key joints, then you have reached the upper limit of hand speed. If not, the linear, horizontal velocity of the hand or translational velocity of the hand, will always be sub-optimal. Biomechanics 101. 5m/s is at the lower end of the scale. The upper limit would be in the range of 15 to 20 m/s.

Great to see hand speed and biomechanical principles being a focus of fly casting performance and coaching. There should be more of it.

Translation is best left to linguists,

John

[John Waters]

Hi Walter,

"If my line hand is moving purely translationally and the highest speed I can reach is 5 m/s is that maximum speed likely to change if I add a rotational component to its path? Would it increase, decrease or stay the same (approximately)?"

Definitely increase as per post 6 above.

John

[Bernd Ziesche]

Hi everyone,
I don't know what the general question to be answered is. But measuring hauling speed, I would think, that we know the length of the rod. This length remains the same, bended or straight. If we have a marked line being pulled thru the guides, we have the exact length of path without perspective based failure and the time. Would that not be more precise compared to measuring outside the rod?
Regards
Bernd

[Walter]

Bernd,

You are correct. Using a marked line is the most accurate way. Having multiple marks could be used to eliminate the perspective issue.

As Gordy pointed out, Tracker is able to measure changes in displacement between two points but assumes a straight line path between the two points. We could do a manual measurement but I’m sure you see the issues with that.

There are a lot of videos out there but not many with marked lines so the question is how to measure the haul in those videos in order to make use of them.

[gordonjudd]

so the question is how to measure the haul in those videos in order to make use of them.

Walter,
There are very few videos of casts made with line markers of some kind so in general I think taking the numerical derivative of the distance between the haul hand and the stripper guide will give values that are within 1 (maybe 2) m/s of the value you would get with line markers.

Maybe you could use Tracker to test that expectation on one of Lasse's casts with a line marker. Both approaches have small errors that come from using straight line, 2D approximations to the actual distances but I think those errors would be quite small since the line curvature or z separation distances are quite small in comparison to the changes in the x and y values.

Regardless of the technique I would think measurements would show that incorporating a line hand haul path that opposed the direction of the stripper guide path would produce higher haul speeds since the stripper guide speed is so much higher than the hand speed.

Gordy