Subtle horizontal tracking issues may not inhibit real-world fishing success, but larger errors are a different story. Seeing errors yourself, or having an instructor’s eyes watching, can of course help you identify a problem. Another tool that can be useful is what I have in the past humorously called the Plane-O-Matic. It comes from Doug Swisher and the late Carl Richards and is a fairly simple way to pantomime your way out of horizontal tracking errors.
I first saw the Plane-O-Matic in Doug and Carl’s 1975 book, Fly Fishing Strategy. As a kid at the time, I sure had fun with the thing, and it has continued to be a useful instructing tool over the years. The Plane-O-Matic’s construction is simple: It’s an 18-inch square piece of cardboard bolted to the end of a foot-long dowel rod. You hold the dowel like a fly rod and pantomime with the Plane-O-Matic, skinny edge forward. If you curve of otherwise mis-track your casting stoke, you’ll feel air resistance from the flat faces of the cardboard.