Want a sliding dropper rig? Nick Thomas has an excellent design that you'll want to try
Fishing a nymph under a dry fly in a duo rig is a great exploratory method. There are many ways of rigging the two flies; the New Zealand style or tying the dry fly to a dropper and the nymph to the point are probably the most commonly used.
I think there is a better way; use a dry fly tied on a jig hook and tie the nymph link to the eye of the dry fly like the one above. See 'Dancing a Jig' in ESF #53. All these rigs are fixed, with the nymph fishing at a set depth below the dry fly, so when you move to a new section of the river a change to the rig may be needed to fish the nymph at the correct depth. With a jig hook dry fly this is simple. Just cut off the nymph link at the dry fly, wind it and the nymph onto a foam rig keeper in case you need to fish the same depth of water later and tie on another nymph with a shorter or longer length of tippet.
But what if you want an adjustable rig? One that can be changed quickly without cutting and retying to suit varying water depths? One approach is to use a dry fly on a sliding dropper. The simplest way of doing this is to tie a grinner knot in a length of tippet around the leader and then tie the dry fly to the downward pointing tag of the knot. Other more complex methods, for example using a dropper tied to a tippet ring trapped between sliding knots or float stops, have been described. I've never tried these; they sound just too complicated to me, and a pain in the butt to have to rebuild on the bank if you lose the rig to a rock or a tree.
There are also methods using a sliding dry fly. One approach involves using two bits of silicone tubing threaded onto the leader and then pushed onto the eye and round the bend of the fly to allow it to be slid up and down to adjust the depth at which the nymph is swimming. Again, this is all a bit complex for a simple soul like me and has its drawbacks. The dry fly must be big enough to be able to jam in the tubing and must be tied with room to slide on the silicone. Also, the fly is tethered at both the front and back, which isn't a great orientation for hooking should a fish take. Like the sliding tippet ring dropper method, it all seems a bit over engineered and prone to things going wrong. There’s another approach which uses a dry fly tied with a length of tippet running through the body along which it can slide. The fly is then tied in line between the leader and the tippet to the nymph, forming a sliding indicator. Again, a bit too complex for me, annoying when you lose a fly that’s taken extra time to tie, and not accessible to folks who don’t roll their own.
So, here's my version of a dynamic duo, a pair that can be adjusted on the go, without any cutting or retying, allowing the depth of the nymph to be changed over several feet. Is it complicated to set up? No. Does it require you to buy or carry any special kit to set it up on the river? Not at all. It's simple as ABC:
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Attach 3-5 feet of tippet to the end of your leader and tie on the dry fly.
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Tie the nymph onto another 3-5 feet length of tippet and thread the free end up through the eye of the dry fly.
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Tie the end around the tippet to the dry fly with a grinner knot, tighten and trim the tag end leaving an inch or so in case you need to retighten the knot.
I use furled leaders on all my river fly lines with tippet rings on the end, which I would recommend, but the same method will work with whatever leader you use. Use a grinner knot with enough turns to make the knot grip on the tippet, I use 5 or 6 turns. To adjust the depth of the nymph below the dry fly simply slide the grinner knot up and down. With a four-foot length of tippet between the leader and the dry fly and a five-foot link to the nymph, the nymph can be adjusted to fish anywhere between one and five feet under the surface, which is enough to fish just about anywhere you would fish a duo.
The dry fly hook eye must be large enough to pass the nymph tippet through it after the dry fly has been tied to the leader. But if you are using the dry in a duo to suspend a nymph, it's not going to be tied on a tiny hook with a very small eye. I wouldn't recommend this rig with dry flies tied on up-eyed hooks, but straight-eyed or down-eyed hooks are fine. I use dry flies tied on jig hooks as that's what I use for my fixed duo rigs and what I carry in my duo fly box. When tying the dynamic duo rig with a conventional jig hook, where the eye is in the same plane as the rest of the hook, the tippet to the nymph is threaded through the eye of the dry fly from one side and then tied around the leader. This means that the rig is asymmetrical at this point, but I've not found that this affects the performance in practice. There are specialist jig hooks, like the Hends BL154, which have the eye at a right angle to the rest of the hook. If you tie a dry fly on one of these and the nymph link is threaded up through the eye everything sits in line. However, if you want to use the same dry fly in a fixed duo rig the leader and nymph link knots are not in a vertical plane as they are with a standard jig hook. You can't have everything, so I stick with standard jig hooks.
The picture above shows my usual rig; a simple tungsten weighted nymph and a nice bushy dry fly to suspend it from. I’ve slid the nymph almost up to the dry fly so you can see the arrangement of the different lengths of tippet. The length coming in from the left corner and tied to the eye of the dry fly goes to the tippet ring on the furled leaded. The tippet tied to the nymph goes through the eye of the dry and then to the sliding knot above the dry fly.
The only difference between this rig and a fixed duo rig using a jig hook dry is the double length of tippet above the fly to the sliding knot. Yes, this may put off a fussy fish from taking the dry fly. However, bear in mind that the primary purposes of the dry fly in a duo rig is to suspend the nymph at the right depth and to act as an indicator, with the chance of taking the odd bonus fish that fancies a floating snack. For me, the small risk of putting off a fish with the double tippet is more than compensated by the extra fish I catch by having my nymph fishing at the correct depth. You know what it’s like if you must retie a rig every time the depth changes; sometimes you just don’t bother and carry on fishing at the same depth and hope for the best. Much better to simply slide a knot up or down and present the nymph properly. If you are facing a rising fish, just snip off the nymph tippet below the knot leaving the dry fly to fish alone. After you've caught the rising fish, or have been spurned, you can tie the nymph link back on and carry on fishing the duo.
For me, this ability to swap back and forth between a duo rig and a single dry fly is the winning feature of the dynamic duo. I used to fish a bit using the sliding dropper knot method, but this way of fishing is not convertible. If you cut off the nymph the dry fly is not fishing optimally and you need to tie some form of knot in the redundant nymph link to stop the dry fly dropper sliding off the end. Swap back and forth a couple of times and you’ll need to tie the whole rig from scratch. With the dynamic duo, cutting the nymph link off just leaves a small remnant of the grinner knot, so when you tie the nymph link back on you just slide the stub of the old knot up the leader out of the way.
So, if you are fishing a mixed bit of water like the section of river above, fishing dynamically is the way to go. This nice piece of water has a long wide run of shallow riffles and pockets coming in from the right, which narrows into a deep pool with a fast current along the far bank and then tails out into a slow water flat. Fishing the upper section needs a short link between nymph and dry fly, a couple of feet at most, sometimes less. Moving down to the deeper run means lengthening the link out to four to six feet to allow the nymph to fish just above the gravel bottom. Finally, for fishing the flat, where there isn’t enough current to drift a duo, the nymph comes off and the dry fly is pitched along the edge of the foam line. Within this two-hundred-yard stretch fish can be found anywhere, will be holding at different depths and open to snaffling either a deep nymph or rising to a gently presented dry. Efficient fishing means using a rig that can be quickly and easily altered to suit the changing conditions.
While the main reason for using the dynamic duo is to accommodate different depths of water as you move up or down the river, it's also useful to explore different depths within the same stretch of water to see where the fish are holding. With this rig it's a piece of cake to drift your flies down a run a few times on different lines with the nymph fishing deep, then slide the knot up the leader and make a second series of drifts with the nymph higher in the water. Fishing this way, you are exploring all the water in three dimensions and maximising your chances of finding the fish.
The photograph above shows another short stretch of river where using the dynamic duo has enabled me to fish all the water effectively. Most of the width of the river from the near bank out is shallow and doesn’t hold fish, but nearer the far bank the river deepens into several channels and pockets formed by the current being diverted by two large rocks. On the near side of the big exposed rock on the right there is a narrow trough (A) around three feet deep. Downstream of the rock (C) is a ridge of gravel and pebbles deposited in the slower current, where the water is only a foot deep. Beyond the ridge the river deepens again into a second trough (B) the same depth as the first. Scoured out behind the large submerged rock at the end of the pebble ridge there is a small pocket (D) about six feet long and five feet deep. It’s not obvious until you get very close to it; I nearly fell in it the first time I fished it. Finally, against the far bank there is a further deep hole (E), gouged out by the current swirling past the large rocks of the upstream bank. The different depths and speeds of the currents running through these sections of the river mean that three different lengths of tippet between dry fly and nymph are needed to fish effectively. I’ve had several days when by changing the height of my nymph I’ve taken one or more fish from each of the different areas
If you are an experienced duo user you can simply convert your static rig to a dynamic one using the same pairs of flies. If you are new to the method, make sure you use a balanced pair of flies. You need a nymph which is heavy enough to reach the bottom over the different depths you will be fishing, and a dry which is buoyant enough to hold it up. The weight of the nymph is the key. You can always raise a heavy nymph up, you can’t push a light nymph down. Getting the nymph down through the water quickly can make all the difference between success and failure. Most of the beginners and some experienced anglers that I meet on the river who are having trouble catching consistently are using flies which are too light and not getting down to where the fish are. It’s a common problem in anglers translating from stillwater trout to the river. They underestimate the influence of the current on how their flies are fishing. On a lake, the weight of a heavy hook will sink a fly a considerable distance provided it’s not retrieved too quickly. The same fly fished in even a gentle current may struggle to sink more than a couple of feet. It will catch some fish, but only those willing to move up or sideways to intercept it.
I fish the dynamic duo on a relatively short line, usually no more than two or three rod lengths from the tip, casting upstream and then holding most of the line off the water, letting the pair of flies drift down with the current. It works very well using a light level nymphing line using the weight of the nymph to sling the duo up and across the current. The placement of the flies and the casting actions are essentially the same as when fishing two nymphs on a short line; see ‘What’s My Line’ in ESF #62. After I’ve made a few runs through a stretch of water, I’ll make a couple more checking the drift of the dry by twitching the rod tip, or even lifting the dry off the water and placing it back down. These actions cause the nymph to rise and fall in the current and I’ve gained a lot of extra fish that grab the nymph at this point.
Finally, he dynamic duo is not just for rivers. If you fish for stillwater trout the same rig is great for fishing a nymph or buzzer at different depths. Finding the level at which fish are feeding is often the key to a successful day on a lake or reservoir. The dynamic duo is a great way of easily trying different depths with the chance of some bonus fish on the dry fly. It's much more satisfying than fishing a bung.
Nick Thomas lives in South Wales. He started fly fishing on Scottish hill lochs many years ago and continues to design, tie and fish flies for trout, grayling, carp, bass and anything else that’s going.