Here we have Doug Daufel, one of the owners (along with his twin brother, Dan) of Montana Brothers Rodworks. Doug is an expert angler and has a long history in the fly fishing business. His casting stroke is interesting. While it contains a number of traits shared with all great casters—vertical movement of the elbow, smooth acceleration, staying in one plane throughout the stroke—it also has an interesting twist to it. Looking at his wrist, we can see that on the backcast Doug meters out the use of his wrist through the entire length of the stroke. On the forward cast, he saves his wrist until the end of the stroke, bringing it to bear only in the split second before he stops the rod.
Is one way “correct” and the other “flawed”? From a purely theoretical point of view, yes. Doug should use his wrist at the end of each stroke. In this way, the acceleration provided by the wrist is additive to that generated by the upper arm and forearm, resulting in a more efficient, powerful stroke. Using the wrist throughout the stroke “wastes” the wrist, because some of the acceleration it provides is acceleration that could have been accomplished with the upper arm and forearm. The net result of this is that the maximum possible speed of the stroke is reduced.
Now, for most fly fishing situations this distinction is meaningless. Any combination of wrist and arm will typically produce sufficient stroke speed to complete most trout fishing casts. But if you do a lot of long distance casting, saltwater flats angling, find yourself fishing in lots of wind, or simply want to be a fundamentally sound caster, it’s another matter altogether. These are all situations where high line speed can be the difference between success and failure. And the highest line speeds always result from using the wrist at the end of the stroke.