I need to make the distinction that with the C-80, it is a "stand-alone" display. The E-80 on the other hand can be shared so that each display will show the identical or different readouts, such as full images of a chartplotter, radar, fish finder, and so on.
This is accomplished by a point-to-point high-speed ethernet connection between the E series displays. The C series displays have no such function.
What the C-80 display can give you though is descrete data output to other instruments, displayed by ether via ST60+, ST70, or other brand display unit such as Maretron, is a digital readout of certain parameters, such as speed, depth, heading, and so on.
But each manufacturer's display has its own set of what it can display, and that is one issue still with NMEA2000 and other networkable devices, so their selection is somewhat dependant on what your display needs are.
Think of it in these terms. Anything that is high-bandwidth like radar displays, chartplotting, or sonar is going to require two hi-end displays, such as interconnected E-80s at each helm station.
But the low-bandwidth data, such as speed, depth, heading, fuel flow; any data that can be displayed as a gauge or digital readout can be transmitted to another display via NMEA2000, Seatalk, or NMEA0183 (pick your poison) at another helm via C-80.
So if you interconnected two C-80s by NMEA or Seatalk, you would only be able to share data such as the gauge type; depth, speed, heading, etc. But if you interconnect two E-80s by high-speed ethernet, you can share radar images, sonar display, and chartplotter data.
I want to make sure you understand the difference.
And to "confuse" the matter further, if you connect a sonar module (DSM300 for instance) to a C-80, it will display the typical graphic sonar image on the C-80, and also transmit depth only data via NMEA2000 or Seatalk.
So you could have the C-80 at one helm displaying the graphic depth sounder image, and a simple graphic readout of just depth (from the C-80) on a display instrument at the other helm. Make sense?
Unfortunately, two E-80s are way above the dollar amount you mentioned, so just the caveat that you won't have two helm displays capable with full images of radar, sonar, and so on.
My setup is on a 1995 Carver 325 with flybridge only (no lower helm).
Here is a tour of my Nav Setup - a bit more detail than the drawing.
http://members.toast.net/boatguy/navpkg.htm
If you look at my setup, you'll notice that I have a graphic display adjacent to the C-80. Its purpose is a dedicated display to display important data, such as Depth rather than having to rely on a tiny depth display on the C-80, as it can get pretty crowded with the data it can display.
So in a sense, I am offloading some of the more important readings from the C-80. As the C-80 is the only depth gauge on the boat, it is important to be able to see it at all times. I can setup both the ST60+ and the Lowrance LMF-200 to read such as that.
By the way, although this might be a bit overboard, it is nonetheless very necessary; at least to me... [
