Figure_1---Water Column

Figure 1—Water Column

Guest Blogger: Michael Vorhis, author of ARCHANGEL suspense thriller, OPEN DISTANCE adventure thriller & more to come

Despite your fervent hopes, sadly this isn’t an article about jiving to Tupac’s rap or disco-duck tunes of the now-ancient BeeGees; we’ll leave that topic for a (much) later post.

I’d like to discuss something dear to the heart of every wetfly and nymph angler: Achieving a productive depth of the fly. This is unequivocally, unarguably the most important aspect of subsurface fly fishing for salmonids (and probably for every other species as well). In fact it’s all ten of the top ten aspects. Fly choice, tippet size, stripping cadences…all pale by comparison; about the only thing more important is whether there are any fish in the water.

As we know, for trout occupying “feeding stations” in the current, the day is one constant meal. The waiter is the stream itself, bringing a nonstop trickle of morsels–nymphs, larvae, drowned adult insect, things that live their adult lives submerged (such as leeches, shrimp, etc.), eggs, crippled minnows, fry. A good feeding station is prime real estate–it provides cover from predatorial view, the ability to rest in position without fighting the current, and a ready procession of snacks. A fish is understandably loathe to give up such a spot. So it’ll move a little left or a little right, a little up or a little down, to grab something edible…but if a thing that could be tasty goes by outside that zone of laziness, generally they’ll let it go by. There’s enough coming right down their gullets that they needn’t spend energy chasing anything. Thus was the concept of the “water column” recognized, to help anglers understand and refine that aspect of their subsurface fly presentation. To catch fish, or at least to catch decent fish, one has to present one’s fly at a productive depth.

Although depth is as important in stillwater fly fishing as it is in streams, I’ll focus on the stream here and save the lake and lethargic backwater scene for another day.

A few ground-rule questions and points are in order:

— Before discussing how to ‘get down,’ we must figure out how down is down. “Where” before “how.” (And the “where” will come back around to including a “how” as well, because our limitations are boundaries within which we must make the ‘where’ decision.)

— How you get your fly to depth is best done with an eye on what kind of fly it is. Does it mimic something that lives in the bottom gravel or muck itself? Is it supposed to be something that can fight or traverse current? Is the fly’s effectiveness dependent upon the animation of its hackle or legs in the current? We don’t want to make a fly seem more artificial than it has to seem.

— How you get your fly to depth has to be a castable solution (or at least castable to the degree you need for the place you’re at; dipping a weighted fly into pocket water a rod’s length away allows some additional ‘get down’ methods, but cannot easily employ others. That’s not really casting (and a personal comment here…dipping offerings into holes and pockets directly from the tip guide appeals to me less than angling that does include the cast, and I think I’m in good company there; casting is part of the art, therefore part of the enjoyment, not to mention the range it affords).

— Does the fly require stripping to tempt a take? If so, what are the snag risks here? Weed? Volcanic rocks? Narrow crevices? Need to consider these things unless you came to catch debris instead of fish. (Sometimes it seems like I did come for that.)

— Are you suspending the fly, such as below a bobber or high-floating indicator fly? Or alternatively, are you bounce-rigging? These two methods use indices–the surface or the bottom–and so they have their own ways of setting depth and sticking to it. There’s a reference limiter at either the surface or the bottom, so their methods of achieving depth can afford to be a little more brute-force in terms of the amount of weight used. This article will therefore mostly ignore these methods; setting and sticking to depth is easier for them and their rules are established using other assumptions.

Note going in that there are no approaches to achieving the right depth that are ideal for all reasons (except when the desired depth is zero, in which case fly floatant and deer hair are neck-and-neck for the most popular schemes). Every method has its aficionados and every one of them has drawbacks. Arguments abound.

How Deep?

The two pillars of this vital question are “know this part of the stream” and “prospect.” If you’re already clear on where the fish should be lurking–for example just off the gravel down through a familiar rapid or run–then you already know where you want your offering to be. If you’re not as clear, for example in a deeper pool where the fish may be hugging the bottom, may be seeking emergers under the surface, may be skulking alongside an abrupt drop-off or may be prowling at the tailout or at a variety of mid-pool depths, then using multiple flies (if stream laws and the tree canopy allow it) can be a superb way to judge productive depth. For simplicity most anglers drop a lower fly off the hook bend of the one above it, but many suffer the extra tangle-prone-ness of dangling each fly on a wisp of tippet that hangs at right angles to the leader because they don’t want the higher fly to be limited in how the current wiggles it around. In my humble experience, this is nice but gets less practical the longer the casts need to be; a fly with tippet tied to its hook bend still produces, but a piece of thin dropper tippet snarled around the leader has never caught a fish for me yet.

Figure 2—A Prospecting Rig

However it’s done, multiple flies should be kept a distance apart that’s meaningful with respect to the prospecting goal–maybe double the distance a fish might move to get a snack. Considering that the line may be slanted during the drift, I believe at least 18+ inches of separation is a common rule of thumb (and one that works for me), but maybe far more, location depending. Everyone has their own ideas here–some go with as little as 15 inches, others more like 30. Sometimes a “dry-dropper” rig will suspend a tiny nymph no more than six inches below the dry fly…but that’s a different case, as it’s done not so much for depth prospecting but to tempt a take from a curious fish that’s too wary to slurp the dry itself.

While prospecting, once you get a take and know which fly was taken (whether you brought it to net or not), you can then cut back to the sweet simplicity of one fly, one depth.

While “ganging” multiple flies on the leader, place them in the sequence based on the nature of the patterns, to ensure that multiple depths are covered. Almost always a fly closer to the tippet’s far end should fish deeper than one above it on the leader (although there are other interesting rigs, and we’ll touch on one later). There are flies that have some natural floatation, so while prospecting it may be best if they’re not used as the point fly, lest you end up with two flies drifting at about the same depth, which defeats the prospecting goal.

The “how deep” question, while the place your quest starts, will come back around and follow some of the “how to achieve depth” tricks. So it’s a circular progression, this quest.

How to Achieve Depth?

The easiest way to achieve depth is, naturally, using weighted flies–although judging how much weight a fly has and how deep that’ll get you in a specific current can be less than a slam…uh…dunk. And note that when you’re working a riffle, you’ll be working more than one kind of water–the swifter tongue of the current, and the convergence lines on either side, and eddies behind obstructions, and rarified micro-zones in front of boulders. If you’re getting strikes you may not care, but if not, then other than limiting your drifts to water of one speed, how do you control the depth to which a weighted fly sinks?

A fly can be weighted by weight-wire (lead, tungsten, tin-based stuff) or by a metal bead-head, or both. It can also sink faster if it was tied with tinsel instead of hair, and/or if it was built upon a heavier hook. Through trial and error you can get it to occupy a given zone of the water column by casting x meters upstream of the area you’re fishing and letting it sink to depth–that’s the timed approach, and it’s what most of us do, although again it’s a repetitive trial process and guesswork is its backbone. And it assumes that fly will keep on sinking as seconds go by and will defeat any natural sink retardation the leader pulls back with.


Figure 3— Unweighted, Wire-weighted, Bead-Head Flies

Many anglers swear by weighted flies and bead heads because of their convenience, and some also believe a shiny round head makes a fly more appealing to fish…and still others like mostly the roundness of a head and use glass beads or dark metallic beads. There are rather huge tungsten front-ends that’ll scoot along the bottom like a sculpin when dragged. But just as many fisherfolk take exception to weighting flies, some noteworthy experts among them. For one thing there’s the “how heavy is a heavy fly?” dilemma. For another there’s the “how do I change that fly’s sink rate?” or more precisely the “how do I dial in the sinking behavior I really want?” concern. And finally there’s the realization that, while unweighted natural insects will move around in the subtler wafts of current, artificials with considerably more mass will not do so as much. The weighted or bead-headed fly’s drift, therefore, may appear more artificial. That’s certainly secondary to getting a fly to the productive depth, but still many expert fly fishermen avoid weighted flies for such reasons, opting to ‘get down’ by other means.

Yet those other means have their own problems.

One thing to remember is that a natural insect dislodged from the bottom begins there; it’s already at depth. Our fly, by contrast, tries to dive there from the surface. To help it along, if it’s an un(der)weighted fly we need something else pulling it down (and quickly…but also not too deep). Enter the sinking line and the ancient magic known as split shot…and here’s where old and new technologies face off, and where clever tricks get a little more tricky.

Sinking Lines

Sinking lines are very effective, as are sinking poly-leaders (which are basically sink tips attached between line and leader). The countdown is accurate–x inches per second, and a little longer to then pull the leader and flies down too, depending of course on leader length and diameter, and on fly count and type. The main few complexities with sinking lines and sink tips are these:

— Perhaps the biggest drawback to the sinking line approach is the commitment to it, both in advance and on the stream–the need to have bought one to begin with, along with either a spare spool or an entire spare reel or even an entire reel-rod setup. And without a second rod all rigged and waiting, one can’t just quickly switch to a sinking line for a given run or hole, then back to the floating line ten minutes later. Poly-leader sink tips improve the ad-lib picture a little, but still require a complete re-do of everything forward of the fly line.

— Like any other line, a sink-tip or sinking line has to be matched to the rod’s ability to cast it. Within limits, this has nothing to do with its sink rate. It’s all about mass, regardless of the mass/thickness ratio that determines how it sinks. A 5-weight sinking line and a 9-weight sinking line can both sink at 7 inches per second, although the 9-weighter will have more non-sinking mass to it, loading the cast more without dragging the line faster down through the water column. Line manufacturers have sink rate dialed in–they can make a length of line do exactly what they say. (Note that seeking to increase the achieved sink rate by over-lining on the “grains” is a bad idea; I tried this once and the only thing I achieved was the belief that my fine rod had turned into a floppy, pathetic noodle–I couldn’t even achieve the distance I could with an underweight floating line. Get the sink behavior you want but stick with the grain-weight the rod is meant for. A 5-weight rod wants a 5-grains-per-foot sinking line.)

— Sinking lines require retrieval of much of the deployed line before pick-up; this can mean much more false-casting to re-deploy a desired length of line, and it can also drastically reduce roll cast distances, meaning back-cast room can become more a necessity.

— Sinking lines pull the near end of the leader down. Is that getting your fly, another 5 to 12 feet further out, down where you want it? It’s an important question. Many sink-tip users maintain a relatively short leader–4 to 5 feet including tippet–to help them control the answer.

— Sink tips of a sink rate identical to a full sinking line will pull the leader down more slowly than the line would, because one end of a sink tip is still held up by the floating fly line. And the shorter the sink tip is, the more pronounced this sink rate degradation and depth restriction becomes. It’s a limitation, but also a detail that can be leveraged to excellent effect in dialing in the depth to which your leader and flies are dragged.

It can sometimes help to remember that sink tips or sinking lines pull some flies down, and for other flies–flies that sink readily on their own–they simply avoid holding them up. While that sounds like a stupid distinction it affects your ability to know the depth your fly has achieved in N seconds.

Full-on sinking lines just keep sinking–from a practical perspective there’s no limiter. You can find yourself encountering snags. Your defense against this is the strip retrieve–you’ll have to count, approximating how long to wait before beginning to “plane” that line in, if necessary with rod tip raised. And the belly of the deployed line can be deeper than the fly when you begin your retrieve, which means for awhile your stripping is dragging your fly deeper into snag territory. By contrast, poly-leader sink tips used with a floating line have one end held toward the surface by the line, so strip-retrieving tends to raise the fly. The stripping can thus often be done more slowly, and the fly can be kept level with the right timing. The limitation (or again, the advantage) is that the depth that can be achieved is no more than the length of the poly-leader (or poly-leader and leader, if the fly will also sink readily on its own).

Part II of this article will discuss use of split shot, water density considerations, leader discontinuities and less common fly setups.


    1. Thanks for reading Joe, I appreciate it. Yep, the complexity never ends. Wouldn’t it be nice if we could just amble out to a stream, same leader set-up as we always use, and wail away? When I began this sport I had that notion, and sometimes I miss being so naive. (I’m actually working on a future blog post about missing those ignorant days right now.)

      But it’s also true that if we want to simplify we can still cut our concerns down to just a few things. For subsurface fishing the “get down” topic is absolutely one of them. Ignore casting form, but do the depth math. Trout don’t want us to know this.

      Part II is going to get even more complicated…sorry about that. Split shot is an art unto itself. And remember that as complicated as they sound, these are still just overviews…there’s a lot of secret tricks out there we’d all love to hear, and I hope to see some shared as comments.

      – Mike

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