The reach cast is a method of adding slack to the line above the fly to allow the fly to float without dragging in the current. (See Figure 1) Unlike other casts that add slack, the reach cast has the slack under control so that one can easily set the hook. It is accomplished by mending the line upstream of the fly while the line is in the air on the way to the target. This is referred to as a “mid-air mend”. For it to be successful though, all of the line must be above the fly when it lands on the water.
Two casting principles are in play with the reach cast. The first principle is: The fly goes where the rod is pointed when it stops. The second is: Whereever you move the rod tip after the stop determines where the rest
of the line goes. (see Figure 2) Because there is a short delay after the rod is stopped, some line fails to mend upstream. If I delay a little, a little line continues straight toward the target and the rest of the line goes upstream. If I delay longer, more line continues on toward the target and less line is mended upstream. Theoretically, for all of the line to be mended above the fly, one would have to mend at the exact moment that
the stop of the rod occurs. However, if one stops and mends at the same time, there is, in fact, no stop and the result is a lack of loop formation. The resulting wide loop often piles line in the direction of the intended stop.
How then does one consistently mend all of the line above the fly while in the air? Pulling the rod back gently as one mends upstream pulls the line that is going straight toward the target back in the same direction as the mend. Thus, all of the line lands on the water in a straight line from rod tip to fly with all of the line