March 17, 2023
By Jim McLennan
Trout aren’t impossible to catch, but they’re smart enough to be difficult to catch and, come to think of it, that’s the whole point of trying to catch them. The difficulty comes courtesy of the trout’s simple, but oh-so-effective instincts. Their tiny brains suck in stimuli and spit out suspicion.
As a result, trout live in a state of permanent paranoia. Their first priority is self-preservation, and this applies to everything they do, including feeding. When a trout decides to eat something, it completes the act only if no warning lights go off along the way.
One of their brightest warning lights flashes when trout see an apparent food item move in the wrong direction. If 50 natural mayfly duns drift into view, all sailing freely on the silken currents, the trout might eat all of them. But if your fly drifts into view and then suddenly skids sideways across the surface like an out-of-control stock car, the trout will refuse it, and might even be alarmed enough to leave the area or stop feeding.
That sideways (or up- or downstream) skid is called “drag” and it is dry-fly fishing’s biggest deal breaker. It doesn’t matter how perfect your fly pattern is—if it doesn’t behave like a natural insect, it’s often refused.
Dry-fly theory can be condensed into these thirteen words: “Get a reasonable imitation to drift directly over the fish with no drag.” That’s it; simple in principle, somewhat more difficult in execution.
Consider Your Position
First things first. Before worrying about casting, mending, or even choosing a fly, think about where your cast should come from.
Don’t simply stand where the wading is easiest, or where the wind or sun is most advantageous. Anticipate what the current will do to your line, leader, and fly before making the first cast. Choose a casting position that keeps you out of the fish’s sight but, just as important, gives you the best chance to get a completely drag-free drift over the fish.
Most fly fishers don’t worry enough about their leaders when fishing dry flies. Some do, however. Does the name George Harvey ring a bell? Harvey considered the leader as important as the fly pattern for fooling trout with dry flies.
Specifically, it’s the length of the tippet that is critical. The tippet is the narrowest-diameter part of the leader, and as a result, it’s limp and more prone to fall in loose coils.
A tippet that’s too short leaves little slack to help achieve a drag-free drift. A tippet that’s long and limp should land on the water in gentle waves, enabling drag-free drifts.
Beware that excessively long leaders reduce your casting accuracy—especially in the wind. In most cases the best length for your tippet is about 2 to 4 feet.
Make the Cast
You can’t avoid drag completely, but you can delay it until after the fly has drifted past the fish. You can do this with various types of slack casts, which introduce additional slack into the line or leader. The slack in the line dissipates due to the pull of the current, yet the fly continues to drift naturally.
The most common slack cast may be the S-cast, or serpentine cast. After stopping the rod on the final delivery—but before the line settles to the water—the caster wiggles the rod tip back and forth horizontally to introduce S-curves (slack) into the line.
The S-cast is easy, and has advantages in certain situations, but for most dry-fly fishing it’s not very effective. For a slack cast to delay or avoid drag on the fly, it’s best to have the slack in the leader, close to the fly. The S-cast puts most of the slack in the fly line, often close to the caster.
The dump cast is a strange-looking cast that can deposit an entire 12-foot leader into a 3-foot-wide Hula Hoop. To do it, move your hand through a wide, up-and-down arc on the final delivery to create a wide, high loop. Near the end of the cast, bring the rod tip down toward the water, causing the leader and fly to drop straight down instead of turning over (straightening out). This results in a lot of slack, almost all of which is in the leader and a little at the end of the line. (Lefty Kreh calls this simply the slack-leader cast.)
Think of the dump cast as regression in casting technique—it is similar to the deliveries new fly casters often make without trying.
The drawback to this cast is that it’s difficult to execute (accurately) in the wind because the high, slow delivery gives the breeze plenty of time to blow the fly off target. The cast also settles too slowly to be effective in fast water because the current begins pulling some of the slack out of the leader before the fly even lands. When fish are rising in slow to moderate current, however, the dump cast is one of the best ways to put slack in the leader.
A tug cast puts slack in the leader in breezy conditions or in tight situations where the high, open loop of the dump cast is impossible or impractical. To make a tug cast, cast low over the water with a tight loop during the final forward stroke. Use a little more line than necessary, as if you plan to overshoot the target.
Near the end of the cast, when you stop the rod and the line and leader are horizontal above the water, make a quick tug with your line hand. This makes the fly jump backward (toward you) a couple of feet before it settles on the water, and this shock or recoil creates slack in the leader.
The tug cast is more accurate and less affected by wind than the dump cast because it is low to the water. It also works better in tight quarters because it uses a low, narrow loop. It does not create as much slack in the leader as the dump cast.
Pocketwater Pile Cast
I’ve found that the best way to put slack into the leader in fast water is to drive the fly at the surface so it hits the water before the leader unrolls, leaving the fly and leader in a loose mess near the end of the fly line. I call it the pocketwater pile cast, but there are probably other names for it. It lands too hard for use in flat water and gets no points for artistic impression, but in turbulent water it works fine.
Dump casts and pocketwater pile casts are easiest to execute with heavily hackled dry flies (like a Wulff), which are air-resistant and don’t allow the leader to straighten completely.
Tug casts are best with more streamlined or downwing drys (like the Elk-hair Caddis) that you can fire directly at the water like a bullet.
There are also situations where combining these casts can solve drag problems. For example, when you are fishing into the tail of a pool from the riffle below, it’s difficult to get a good drag-free drift because the water where the line lands moves quicker than the water where the fly lands. The line immediately pulls the fly downstream faster than the current.
To solve this problem, there must be slack in the belly of the fly line as well as slack in the leader. Use a dump cast, and then add a few side-to-side waggles of the rod tip before the line settles to the water. This usually produces adequate slack in both places.
Jim McLennan is the author of Water Marks (Fusion Books, 2008) and Fly-Fishing Western Trout Streams (Stackpole Books, 2003). Jim and his wife Lynda own McLennan Fly-Fishing Schools (mclennanflyfishing.com).