Not “dumb” questions at all. I don’t pretend to know all of the technology. There are other members on the board who can cite more of the physics and electronics jargon, but here is my semi-simplified opinion.
**Flashers emit more rapid electronic pulses than most LCD units, especially the lower wattage models. These bounce back and are recorded as flashes on the round dial screen, according to what depth the signal encountered something more dense than water. That can be tree branches, fish, floating debris or weeds…and even your lure. **
The bigger the object, the larger the line on the flasher. Your jig will be a thin line, which moves up and down as you move your rod. Fish show up as thicker lines, and tend to come and go on the screen as they swim through. In a modern hi-tech system, like the Vexilars and Marcums, the strength of these signals is indicated with colors. When you learn to read the flashes, and the colors, you can tell when a fish comes into the “cone” of the transducer signal, and when it gets closer to your lure, by the changing of the colors.
You can also tell the depth of the approaching or hovering fish, relative to where you have your jig positioned, so that you may raise or lower it into the “zone”. On days when you are fishing just off the bottom, and the fish are cruising through several feet above the bottom, you will be able to score a lot more action by adjusting your presentation. Most fish will rise slightly to take a lure, but few will go downward.
Some of the higher wattage LCD units will also show this “real time” activity. Your Fishing Buddy will not. You have to stretch the budget by a couple hundred dollars to get into the real time realm.
**Yes, the flashers will work fine on a boat, tube or 'tune. However, unless most of your fishing is vertical…jigging for suspended fish or fish orienting to structure…you won’t gain any advantage by using a flasher. **
Most anglers who use sonar as an aid while fishing from a boat, tube or 'tune use it more to find structure, determine bottom composition (grey line) and maintain depth than for finding fish. Sure, they show the fish all right, but most of us catch many fish we never saw on a screen, by casting away from the cone of the transducer.
While I have never been a big fan of the Fishing Buddy, I would rather see someone have and use one of those than to fish totally blind. They do not have a lot of the refinements of larger and more expensive units. However, once you learn to read your unit, and adjust your presentations accordingly, you will catch more fish than if you fish without one. Fishing Buddies have a lot of fans who are completely happy with them.
In fairness, Bottom Line (makers of the Fishing Buddy) makes several other sonar units that do much more, for a reasonable investment. If you plan to do more open water fishing than ice fishing, I would recommend their Tournament 4100. It is a little over $200, and has some real time display functions. It will also work well for ice fishing, if you can keep the LCD screen from freezing up.
If you go to a favorite search engine, and plug in “fishing sonar” or something similar, you will get lots of sites. Many of them have buttons that you can bring up tutorials that will explain much more of the science of sonar. After that, you need to develop your own “art”…to be able to read and use your unit for maximum efficiency and enjoyment.