The Royal Coachman is one of the original mayfly imitations. A feather wing fly that can be used on all water. Petty much a dry fly fishing staple, if you don't have any in your fly box, you better get some.
If your looking for a fly that floats nearly all day, then look no further. With a spun deer hair body and feather wings it's great match for caddis, beetles, and mayflies and will float all day with the smallest amount of floatant.