As a kid, fished offshore and caught fish. Also went out with dad in boat and he had a green box flasher. Fast forward 45 years and I've got a chart plotter/live scan and a side scan unit on my boat. The live scan is nice but you really have to learn it to be like the guys on TV and I'm not there yet.
If you get a lake map/topo, you can see where the points are, the underwater river channels, and steep banks (lines close together). That's all you really need to catch fish.
In spring time - fish like flats, summer they'll be deep enough to stay cool and winter deep enough to stay warm. Spring and fall are movement periods for them.
If you are buying a boat - yes, get a fish finder. I use a Striker 9 with side scan and bottom scan and that does 90% of what i need. The live scan shows fish moving. If you are looking for crappie/specs in 30 feet of water you don't need live scan, the down/side scan will do that just fine.
