Originally Posted by randyflycaster
In Tom Rosenbauer's book he describes upstream nymphing this way: He makes a tuck cast then retrieves the tight line at the same speed as the current. He doesn't use an indicator.
Here's my question: Because the water near the bottom of the stream is moving slower than the water on the top, why wouldn't we leave slack in the line and use an indicator? Wouldn't this help prevent the nymph from drifting too fast?
Short answer yes, but you would miss the strike. You can stop reading now.
It is obvious that for an indicator to instantly register a strike, the leader between the indicator and the nymph must be tight. Like fishing on the surface, a tight leader
under the surface also means drag.
It cannot be otherwise. Any slack between the indicator and the fly and the indicator will not move until the fish removes that slack. This delays strike detection and gives the fish time to spit the fly.
There is no free lunch.
When the leader is tight, the indicator is dragging the flies downstream.
When your guide tells you to mend the indicator upstream, why does the guide tell you that? It is because he wants to remove the downstream drag to allow the nymph to sink a bit deeper. But if a fish takes the fly while the slack is present you will miss the strike.
So you can leave slack
between the indicator and the fly to get the fly to sink lower and drift at the speed of the deeper water, but the indicator will not indicate the strike.
One then must ask, if you need to keep slack between the indicator and the fly to get the fly to drift without drag and the indicator can't register the strike, why not fish without an indicator.
This is exactly what Rosenbauer is doing.
What the indicator is doing is changing a sensory method of detecting the strike (feeling the fish take the fly) into a visual form of detection (seeing the indicator move). It is essentially changes nymphing into a form of visual fishing like dry fly fishing. Hence it's popularity. It is easier to teach a fisher to pull when the indicator moves than to teach direct line nymphing.
It is apparent that the nymph must be close or at the bottom if the fish are close or at the bottom. When fishing fast water that varies in depth in a single drift as occurs in the Madison River, indicator fishers will drift their flies too high above the deeper bottom transitions.
The water at the surface flows faster than the water near the bottom. Depending on the gradient (slope of the stream) and the bottom structure (smooth, gravely or large rocks) the speed of the water at the bottom is about 1/2 to 2/3 of the surface speed accoring to Gary Borger.
So if you were to simply cast a weighted nymph upstream, the fly would land UP stream of the fly line and leader, and the fly line on the surface would pull the nymph downstream. This would limit how fast the nymph could sink, plus the sinking nymph would be dragged downstream faster then the speed of the water level the nymph was at. So downstream drag would be evident in the drift of the nymph. If the fish are feeding at or near the boom, the time taken for the nymph to sink to the level of the feeding fish has shorten the "effective" length of the actual productive drift.
A tuck cast flips the fly downstream of the leader and fly and the fly is the first thing to hit the water. The section of leader above
the fly is floating downstream faster
that the fly so this provides a drag free drift allowing the fly to sink as fact as possible. Also the tuck cast actually drives the nymph into the water so this downward force sinks the nymph even faster. The faster the nymph gets to the level of the fish, the longer the "effective drift length.
Retrieving the line and keeping as much line off the water as possible, minimizes the downstream drag on the nymph and allows for strike detection.
See the illustration below from Jason Borger's Nature of Fly Casting
. The tuck cast is the solid line.
Gary Borger taught me the tuck cast. An important part of the tuck cast is that there has to be enough vertical space under the loop, for the leader and fly to flip over an tuck under so it lands DOWNstream of the leader. If you cast at a downward angle as a normal delivery cast, the flipping leader will hit the water and the the leader and the fly will hit the water before it can tuck.
Notice the forward and slightly upward movement of the rod after
the rod stop (F). This is a forward and upward mend that creates more vertical space for the cast to tuck.
So a tuck cast does two things. It gets the flies to the bottom without drag so you get the longest effective drag. You will get a longer effective drift than you would with an indicator. Secondly, when there are water depth variations in drift, the straight line method keeps the fly closer to the bottom than an indicator method. Again this increases the "effective drift", that portion of the drift that is in the zone of the fish.
There are times when indicators are the most effective method, slower flows over even water depth. The speed differential between the bottom and the surface is less. So the indicators do drag the flies downstream but the speed differential is minimized. It is hard to keep the weighted flies moving at the proper speed in slow flows when direct line nymphing.
The second situation is when there is a lot of sunken material like logs and twigs. The nymphs catch on the bottom all the time. Direct line nymphing is a nightmare in these waters - constant snags. So use the indicator to keep the nymphs above the bottom whenever there are snags.
Indicators are an advantage whenever you want to fish at a particular depth than on the bottom. I think the still water fishers use them quite often for this purpose.