This is an old trick used by fly fishing guides who fish out of drift boats. Often times while the guide is maneuvering the drift boat through complicated currents in fast water, the client can lose a fly on a fish or a snag. The guides need a super fast way to get the fly back onto the clients line so they can focus their attention back on the water and the client can get their fly back in the water. The by product of this need is ‘The Clinch Knot on Speed’.
This is the fastest way we know of tying on a fly and getting it back on the water. While it may knot be as calculated and precise as other knots or methods, it can be used in a pinch. And can sometimes save the day whether wading, or fishing from a boat.