Lots of questions and variable to consider.
Three keys here once you actually locate the crappie. Depth control, speed Control and and Presentation of the bait. I will cover each in turn.
What I see lots of guys doing is sitting up on the front bow of the boat on the raised platform and slow trolling with the trolling motor. They mount the deph sounders transducer right on the trolling motor so that they can see what is Straight down under the boat when using a small cone angle transducer. 200 Khz frequency should give you a 20 deg cone sound wave. The use rods off the front of the boat. Once you figure the Real Depth of the Crappie and not just the distance the crappie are from the transducer (very important point here because if you are a foot below the crappie when they are suspended you may not catch them) set the bait on your drop shot rig to the proper depth. One way to do this is the troll over water that is say 10 ft deep and then drop your drop shot rig down until it's on the bottom. Take a magic marker pen and mark the fishing line at the reel. Now when you go out over the deeper water to fish for 10ft deep suspended crappie you can let out the line until your mark is right were it was before. Now you know your bait is at 10ft deep.
If you go slow <1.0 mph and if you really go slow 0.5mph then you are going to catch some fish if you drag the right bait at this speed though a hungry school of crappie. Another thing that I read about that can be critical is the direction that you troll. Troll with the current not against it. Go with the wind. I should follow my own advice here as I often troll into the wind by necessity. I did get a drift sock last year and intend to put it to more use this season and troll or drift more with the wind. Again I read that it's best to troll with the wind in a magazine article so that that advice for as such. Fish do tend to face into the current and it makes sense that they are used to seeing the food coming with them with the current. But that does not mean if a minnow swims by them and into the current that they won't nab it too. Control the speed of the boat as it will help you control the depth of the bait. One thing to think about is the line diameter and how much line you put out. I like to fish vertically and slow. So I tend to fish with about 10ft to 20ft of line out into the water. Most of the fish I graph are suspended at 10ft or 12ft below the surface but that may vary depending on the water quality of the lake YOU fish. My lake is stained water color and deep. over 55ft deep in spots. If you use light weight or thin line there is less resistance and the line will hang down straighter and not have as much friction with the water. If you go slow the line will hang down straigher. I also add lots of lead weight to the line. You said you like to drop shot and that is exactly how I fish too. I tie my jig or hooks onto my main fishing line with the palmar knot or a loop knot and leave about 18" of tag line below the loop knot or palomar knot. That way I can attach a 1/2oz Bass Pro Shop Finesse Lead weight to the tag line. I tie an overhand knot a the end of the tag line to help keep the weight on. These weights can be replaced on the line quickly but they come off easily too when snagged. I would get a lot of them and keep different sizes in my tackle box. but you can use any type of lead weight or other material that you like. The reason for adding the weight below the jig is to keep the line TIGHT. Remember when you were a kid and try to make a telphone out of two tin cans, some string and a couple of buttons? When you had the string tight the thing worked. But if you had any slack in the string between the two tin cans the thing failed to work. You must maintain a tight line between the pole and the lure. This is why I love the weight below my jig. It pull the jig down and keeps my line tight even in a wind. I started out using 1/4 oz weights and now I like the 1/2 oz weights on my 1/16 jigs. In high winds and faster boat speed with thicker line you may go to 1 Oz weights to maintain contact with the jig.
Ok thats about it. If you want to drag the lure behind the boat then I will defer to someone else on how to do that. I would suggest that you keep records of the different lures you use. the line sizes or types and the boat speeds and then try to figure out a chart that will tell you the depth your lures area traveling in the water while going a certain speed using a certain lure and a certain line diameter. That way if you find fish at say 15 ft you can look at the chart and figure out which line to use, which lure to use and what speed to go to make that lure go down to 15ft. Find different areas of your lake that where you have a clean bottom and have fairly constant depths. Then play around with your speed and lure and line and amount of line out behind the boat to see when the lure hits bottom. Write this down and make a chart to that the next time you go out you know what to do.
I have found that getting the right depth of the lure is the One of most important thing. And depth is determined by the other variables,
Originally Posted by J.T. Crappie Guide