It looks like the ideal data source for Reefmaster is a Hummingbird unit with sounder/GPS and logging.
I'd like buy a sounder on the cheap that I will be using specifically/only for ReefMaster - I'll just be installing it temporarily to map some small areas on a local lake then no longer using it.
Could someone recommend any Hummingbird sounder models or model ranges (preferably something older I could find used) that would be good for this task?
Thanks - djm