The reach mend or aerial mend Here's a very useful cast. Takes a little practice, but is a very useful addition to the repertoire.
What we are trying to do is put a kink in our fly line as we cast instead of the traditional straight line presentation. This has benefits in coping with drag by creating some slack line that can reduce or eliminate the drag. ie Casting across different current lines, or if a fish is sitting in front of an obstacle such as a rock. Often even when you are directly below a fish there will be different current speeds that will cause drag.
It's easy enough to do......On the presentation stroke, stop your rod, and as the loop starts to roll out, move your rod tip to one side then back to centre, before continuing to lower it as you would normal do. This results in a curve (in the direction you moved your rod tip) in the line as in the diagram. Now that's the easy part. Controlling it so you can do it on demand and to the degree required for a particular situation requires practice!!
The interesting thing is that it doesn't effect your accuracy, as it occurs after the fly is already on it way to it destination, although judging distance is more difficult.
If you're good at shooting your line, you can shoot your 'kink' well out across the water.
Taking it further you can wiggle your rod tip left and right to create the 'kinky' cast (better know as a wiggle cast) which can be useful when casting straight up stream or down for that matter
Steve
Flyshop 2005