as the title suggests, this technique has several names but in my heart it’s the Wiggle and since i like things that wiggle… i’ll stay with the jiggly moniker !
just as in Pavel Kupstov‘s description and super-excellent video below, its main purpose is to easily and very quickly shake/fling off water from a waterlogged dry fly or emerger during the backcast lift without having to bring the fly back to dry and/or treat it with more floatant or powder.
as we’ll see in the slow-to-fast sequences in the video, the Wiggle sheds most if not all residual water on one single backcast enabling the angler to complete the cast and present the fly with one p/u and lay down instead of having to whip the line back and forth, false casting to get the same result.
how does it work ? just as with a standard casting loop, most of the water is shed when the fly goes from one direction to its opposite direction (back to front/front to back) but in this case, there’s a whole lot of direction changes before going into the actual backcast loop and this latter one finishes flinging off whatever water was left. pretty ingenious when you think about it.
the Wiggle also sheds water from the leader and fly line, something that will greatly help when using a silk or textured line and furled or braided leaders but ‘standard’ mono leaders and plastic fly lines aren’t immune to ‘water retention’ either.
in both cases, fly and line(s) won’t be spraying fish-spooking residual water droplets upon presentation, something to keep in mind in slower flowing pools or stillwater.
as for this pick up’s history and other names, i have no idea if other authors have talked about this p/u method previously but Joan Wulff writes about it in Fly Casting Techniques and Jason Borger in Nature of Fly Casting.
Joan calls it Horizontal Humps and Jason, Wiggle Pick Up. i might have missed it but interestingly, neither one mentions the p/u’s fly-drying attributes as its described as a way to effectively pick up fly and line from vertically oriented snaggies like grass and brush without, well, snagging them so there you go, yet another reason to add this technique to your bag of tricks.
as for how-to’s, wiggling is pretty straightforward but i always advise to start off the lift with the arm extended, rod tip pointed directly at the fly and start wiggling as you’re drawing the elbow back towards you whilst lifting the rod tip and then going into the backcast propper. this avoids ‘running out of casting arc’, leaves more space and time to get it all done correctly and smoothly and generally leads to a better backcast loop. Pavel’s one of the finest casters there is and despite that we’ll see backcast loops that aren’t picture-perfect but that’s not important as long as we don’t lose control of the line and flop it around.
last note: in her same Pick Ups chapter Joan also writes about a variant; Vertical Humps. basically the same thing but instead of wiggling (humping?) left and right, the waves are created by jiggling the rod tip down and up during the lift and since it doesn’t really matter which plane the waves are going, there’s yet another option for you.
there might be more but i can only think of one potential minorly negative aspect: all that spray goes straight towards the caster but then humping usually involves some kind of, ehhhh, nevermind….