One of the most common questions emailed to me over the last several years through NGTO is "What is a dropper, and how do I fish it?" Fishing a dropper, whether it be the traditional dry and nymph, or double nymphs, midges, or streamers, can be very effective in all types of water and is a great rig to go to when you are fishing an unfamiliar stream.
Basically a "dropper" is defined by any fly fished in tandem with another, no matter what type of fly, tippet length, or knot. For example; On the Chattahoochee one of the most effective dropper rigs consists of an elk-hair caddis on top and a small bead-head prince fished as a dropper. That particular rig may look something like this:
There are many variations. Another popular rig might use something like a #10 or #12 wooly booger with a smaller prince, pheasant tail, or even a smaller woolly booger as a dropper, (sometimes called a trailer in this case) or two nymphs, a dry and a midge, the possibilities are almost limitless.
There are also many ways of attaching a dropper. My favorite way to fish this type of rig is with floating line and a 7-9 ft. leader. Attach the leader to your line as you normally would. Tie on your master fly, then cut a section of one size smaller tippet 12-20" for your dropper (downsizing your tippet for your dropper will help your cast roll-over correctly.) Tie one end of this section to the back (the bend) of the hook using a clinch knot. Attach the other end to your dropper. Other possibilities for attaching a dropper include attaching the dropper with a loop knot. Attach the leader to your fly line, make a loop knot in the tippet, and attach 12-20" of smaller tippet material with a loop to loop connection. Then tie your master fly to the tippet. Tie an improved clinch knot just up from the tippet loop knot, so you end up with a short length of line to which you will tie a weighted fly.
When fishing a dropper extra attention should be given to casting. Remember that a sloppy cast or a fast cast can cause the dropper fly to slam into the water or collapse and tangle. Ideally in most cases the top fly should land first and the dropper will loop over softly into the water. As with other flies, both dead-drift fishing and quartering, and stripping can be effective in different situations.