might have contained some wrong information, so I'm re-posting this as an edited version:

My memory is a bit vague on this but at one point, I read Nobeltec removed compatibility with certain versions of BSB/Maptech charts and I know for certain they withdrew support for S57 NOAA ENC.

I just searched this info up and found this 2006 link http://www.sailnet.com/forums/gear-maintenance/45502-what-going-nobeltec.html#post348231

I also found this Feb '04 newsletter link with reference to the BSB Maptech chart formats. Scroll down to the section on "Nobeltec Raster Buy-Back Program": http://nobeltec.com/newsletter/newsletter0204/newsletter.html

You could find more if you wanted to take the time. It was no coincidence they were also in the chart business and the software worked great with Nobeltec charts that cost about $175 per region and were expensive to update, but they were real nice guys and offered special Nobeltec chart deals on an individualized basis to users who complained. I was one of them. I was a VNS user at the time and wasn't happy about them backing away from ENC support. Since our taxes were paying for free updates in electronic format I wanted my nav software to be able to read those charts and updates which could also be downloaded for free. Support for these or other formats might have been added back into the Nobeltec suite since then, but I switched and never looked back although I loved the software (it was/is terrific) -- but didn't love the company's policies.

The Radar PC dome uses an RS-422 interface and the interface box you need converts RS-422 to USB. They used two different makers (that I'm aware of) but one was made by SeaLevel. It had two ports, one was RS-232 and could be connected to a GPS or other serial NMEA device, and the other was RS-422 and was connected to the radar scanner.

See installation guide. http://cms.nobeltec.com/NobeltecCMS/Files/Documents/Products/PDF/Radar_Installers_Guide_2kW.pdf

Here's a link to the SeaLevel product. I'm pretty sure this is the one they used. http://www.sealevel.com/store/serial/asynchronous-serial/usb/2203-usb-to-2-port-rs-232-rs-422-rs-485-db9-serial-interface-adapter.html