Corgi,
I confess my interest and ignorance on your vexilar? How in the world do you watch fish going up and down after your lure with that gizmo? HOw does it have a motor in it? I see that the new fishfinders have pretty amazing view of actual fish swimming up and down or following lures but I have no idea how that machine does it. I guess I'm showing my millennial-properties?
You may be referring to underwater cameras which are fun to watch, but the vexilar is a sonar unit that pings sound to the bottom and comes back to the receiver within the transducer. The time it takes to return determines depth. This same sonar signal will also bounce back off any fish in the path and they too will register. Even schools of minnows can be seen.
By turning up the gain, I can see my small jig, see the pics on the previous page, and they show up as a small red band between the surface ( 0 ) and the whatever the bottom depth might be which is also represented as red. The jig can be seen going to the bottom and when slowly swimming it upward, and fish that may be following it will also show up as a band. The red band representing the fish and the smaller red band representing my small jig are easily seen. When the red band that represents the fish swims up to and blends in to the red band that represents the jig, pay very close attention to the spring bobber, as that is when a very subtle bite occurs. It's almost like cheating to be able to watch them this way. I can also observe their behavior in how much they are willing to move for a proper presentation. One can see when they are aggressively biting, when they are going off the bite, and when they are in a totally negative mode.
Back in the early 90's, a much smaller number of guys were using Vexilars, but go to any lake ice fishing in the northern tier of states nowadays, and everybody has them. Many models that range in price from a little under $300 to over $600. They do make a huge difference.
I usually drill about a dozen holes 10 yards apart, walking away from my portable shanty and then back again drilling a hole every 10 paces or so. I put down the auger and then take my Vexilar to the first hole I drilled and put the transducer in the hole and look. I'm looking for either suspended fish which are very easily seen, or fish near or on bottom which are a little harder to see, but a few seconds watching the screen will tell you if anybody is home. If not, move to the next hole. Lather, rinse, repeat. Some days, it takes augering only a few holes to find them, and other days 50 or more. But once found, let the dance begin. I also will drill a few more areas near any productive holes I've found and move from hole to hole in a general area, as staying at one hole is not as produtive as moving from hole to hole picking on active fish.
