I've been using a slip bobber/Senko set-up for the last two seasons and this one as well. It allows to fish two rigs at the same time - legally - and with a partner, it gives us four presentations. I'm usually working a drop shot on my second rig and a partner might be working a spinnerbait or tube. Fishing alone, I've had many doubles; fishing a partner, we've had 4 "quads" over the years. Talk about a lot of fun! H
The bobber stops can be found at any sporting goods store - even WalMarts. They have the stop set-ups & small plastic beads in the package. You can find the cigar floats at Dicks; you can use all kinds of slip floats in this application, but after trial & error, I've pretty much settled on this one. It's about 4" long and the bright colors make it easy to see, even in a decent chop.
I've chosen Fireline Chrystal, as my main line, because it stays on the surface of the water, between the float and your rod tip. This makes slack retrieval much easier, as well as hook-sets. And, for me, it's easy to see! The glass bead under the float prevents the eye of the crane swivel from sticking in the bottom of the float. (There actually is a method behind my madness, believe it or not!) It also ads a little weight to help get your Senko down faster.
Do NOT use a barrel swivel! You know....the kind that are used with "snap-swivels". Use a quality crane swivel or ball bearing style only. These turn much easier than the barrel types. The Senko hanging below a bobber, has a tendency to turn....so you will need to avoid line twist, as much as possible. I really like to use the Spro Powerswivels, size #8 or #10. They work as well as any ball bearing swivel, but they are expensive and not easy to find everywhere.
You can use any hook you want; however, I would highly recommend you give this one shown a try (crush down the barb!). I've had excellent results with it. When the bobber goes under, you just start reeling her in! The leader between the hook & swivel is anything you want it to be. If I'm fishing fairly shallow in weedy/wooded conditions for LM, I'll beef it up to about 10# test - or more! But for open water SM fishing, the 6# test cited above is about as good as it gets.
Now....the most important part! How far up the line do you set the bobber stop? This is what I do. I find bait on the structure I'm fishing. Then I attach an ice fishing depth finder - the lead weights with the alligator clips molded into them - to the hook. I lower this boatside until it hits bottom. I adjust the bobber stop so that the float is about 2' underwater. This will be correct, for having your Senko presented 2' ABOVE THE BOTTOM. Got that? Simple...effective. Remove the depth finder, slip on a Senko. Cast it a short distance from the boat. The float will lay flat, until the Senko is at the end of it's travel. Now the float will semi-stand up, bouncing about and imparting a rather dramatic action to your wacky rigged Senko.
Lots of folks have a prejudice against bobbers. I guess they automatically associate it with live bait fishing, but it's quite different. You still need to present your Senko in front of fish and and you have to find them! I've posted here, previously, my technique of how I wacky rig these Senkos, so you can do a search on that. Hope this is of some help to some of you folks.