Can anyone speak to the quality of the fishfinder on Garmin 5 series (540/545) chartplotters? I know you need to buy the GSD21 black box to feed in the transducer, but if the quality isn't there, why spend the $200 for the black box.
you don't need the black box if you buy one of the "s" series. they include fishfinders. if you do not buy an "s" series, and later want to include sonar, then you would have to use the GDS21.
Hybrid Mode
