This is the third of a series of articles written for Vagabond Flyfishing Magazine , this one a little more detailed still and focusing on the relationship between rod flex and casting arc. You can’t escape it, fly fishing is about fly casting, or at least that is the starting point. So in the next few pieces for Vagabond I am going to be looking at some structure in terms of what makes fly casting work, what is happening when it is going wrong and how to fix it. So this and other articles on casting will also appear on The Fishing Gene Blog, for the benefit of those yet to discover Vagabond.
Following on from the previous articles some slightly more advanced thoughts on the mechanics of fly casting.
Last time we looked in some detail at the concepts of arc and stroke, the basic movements of the fly caster and those which ultimately determine the track of the rod tip and thus the movement of the line and shape of the loop.
Trouble is that with fly casting, unlike any other form of casting in different types of angling, one is not casting a constant mass; the weight of the line cast varies all the time as a function of the length of it out of the rod tip.
So how does that change the structure of the casting stroke?
The issue here is that the more line out the more weight and the greater the inertia and it then follows that the rod will load more (bend to a greater degree). In effect then the rod gets shorter under more load and flex, “The effective rod length”.
If one is aiming to move the rod tip in a straight line the starting point of that straight line is the height above the caster that the rod tip finds itself when bent. The more bend the “lower to the ground” the starting point of the stroke and thus the wider the casting arc has to be. Now that isn’t very easy to explain in words but perhaps a diagram will assist in understanding.
Images are copyright protected and generously provided from Tim’s latest book on casting which is still in the process of being completed.
In the above diagram the rod has been bent to 80% of its original height above the angler. So the correct point to start the stroke is with the rod at an angle which starts the stroke with the rod point at this height. In other words the starting point is where the tip of the rod at zero flex is in line with the tip of the rod under maximum flex..
If you let out more line, or to a point apply more force the rod will bend more, the effective height above the angler will reduce further and the starting point of the stroke will have the rod at a greater angle.
Above, you will note that as the rod bends more deeply the starting point of the stroke is at a greater angle, and the width of the casting arc becomes greater. More line out requires a greater arc and longer stroke.
In addition to the above obviously the more line out the more power that is required , but one of the absolute keys to casting a fly line is to adjust the arc and stroke as the amount of line in the air changes (or as the amount of rod bend changes if you wish to think of it like that).. For the most part anglers adjust this naturally but understanding the relationship is the key to spotting the cause of some faults which may appear in your casting.
So what happens if you don’t get the adjustment correct?
Although there are more than a few ways of creating tailing loops, those annoying squiggles in the line which look remarkably like the ebola virus and which can be as devastating to your casting, resulting in tangles and wind knots in your tippet. Virtually all of them stem from the rod tip dipping down below the ideal line and then flipping back up again. Failure to extend the arc and stroke as you let out more line will cause the rod tip to do precisely that, dip down and climb back up again during the cast which will result in the line doing the same.
In the diagram above one can see that based on the amount of flex in the rod it should have started “lower” and the arc should have been wider. Now the rod starts in the incorrect position, the rod tip bends down as it loads and then springs back up during the cast producing a tailing loop.
This isn’t the only way to get a tailing loop but all of the various faults that can cause one are based on the same thing. The rod tip dipping down in a concave arc and climbing again. Next time we will look at a couple more ways that you might inadvertently produce the same effect and create wind knots in your line.
Tight lines and tighter loops.. and of course MERRY CHRISTMAS. 🙂
Tim Rolston is a fly fishing guide, past World Flyfishing Championships competitor, captain and coach, an IFFF certified fly casting instructor, fly tyer and author. His book “Learn to Fly-Cast in a Weekend” can be downloaded from his website at www.inkwaziflyfishing.co.za . He is also available to run fly casting workshops for groups, clubs or fishing venues as well as offering personal tuition. Tim can be contacted on email@example.com