Puddle Casts create small S-curves in the fly line and leader that will alleviate drag problems in downstream presentations. Until the current straightens out the line, the s-curves allow the fly to proceed downstream in a drag-free manner.
Starting with an overhead cast, stop the rod high on the forward stroke. The line will travel horizontally over the water. Before the line has a chance to straighten out, drop the rod tip into the water surface, smoothly. This drop will produce a steep angle of the line from the water surface to the fly and cause the line to drop into a number of small s-curves.