Raytheon ST 40 or 60?
I have been looking at depth and speed instruments. The chandlery I spoke with sells both the ST40 and ST60 lines.
ST40 is more affordable and has recently had a price drop to convince people to but it over the ST60. The ST60 seems to be more flixible in setting up repeater displays, etc...
With just a basic unit you will probably find the ST40 all you want. If you are going to buy a whole suite and go big time the ST60 series offers lots of features that are nice ... like repeaters in the Nav station, etc...
Not sure exactly how accurate all of this is but is what I have absorbed of what I have been told.
Ideally I would buy a ST40 bi-data with depth and speed for the port bulkhead and then put a repeater on the Stbd side. I believe this is not possible with the ST40 but is with the ST60.
Hopefully this gives you an idea of the types of differences between the two series.