Bob,

That's the problem with things like that.

It's not really a 'rule'. 'Rules' suggest a governing theory, an agreement about the factors involved, or maybe, at least, some common sense appied. I don't where it came from, but I guarantee that someone just made it up, and it has just about that level of validity.

There are way too many variables involved here, and I doubt that '1.5 to 2 times the water depth' is 'correct' more than about one time in twenty.

In my book, that's not a 'rule' but a W.A.G. (wild a## guess).

The speed of the current, the differences between that speed at the surface and what it changes to as the depth changes, the actual depth of the water, the bottom composition, not to mention the mood of the fish can all change on any river or stream by moving just a couple hundred feet. Differences in the amount of weight used, the weight of the flies used, and their water resistance will have an impact on this as well. So will the density and thickness of the tippet/leader used. Changes in ANY of that will all require either adjustments in the indicator/weight/flies equation, or the conclusion that it really isn't all that critical to the fish and we'll just fish it as it's rigged.

That anyone would believe that you can apply such a simplistic 'rule' to something as complicated as this is patently absurd.

It probably came from someone who spends their time writing on message boards or for magazine articles and little of it actually fishing.

Buddy