We have had a Furuno navnet 3D MFD unit with DSS Radar on Taipan since late 2010. There have been a number of issues. The first problem was with the charts. We had purchased the Navionics MapMedia wide area folio for Asia. The charts were so inaccurate that we had to use the satellite overlay to see some of the islands in Phang Ng Bay. Furuno, eventually supplied replacement Jepperson charts for our unit. Now we will only use the Jepperson MapMedia Charts and have found them very accurate in Asia, Africa, Caribbean, Bahamas and USA.
The Navnet has had a few unexpected shutdowns which are always alarming. Usually at a most inopportune time. The first fright was "HDD Warning. Consult Dealer" I received a lot of conflicting information on this one.... including replacing the hard drive as an option just around $800 to $900 and luckily we were in South Africa at the time where repairs were not a really enticing option. I eventually found out that that is just an error which should not appear and was incorrectly written in the coding somewhere. It should be ignored and will go away if you turn off Tides and Currents. In our experience it does!
If the unit has been on continuously for a long passage we have found that trying to do lots of functions will crash it. If we turn of the main power and then re power and re boot the issue will go away again.
The Radar has failed on route to the Bahamas with a "Tuning Warning" The magnetron still spins but the Radar Display wont come on. David, following various tips on websites, unplugged the plug in the Raydome after confirming that there were no wires preventing the Magnetron from spinning, and replugged it but then we lost everything. Now the GPS is not being seen by the MFD.
We also had to Reset Defaults in the Chart Menu because the purchased charts would not show up any more either.
We spoke to Technical Support via Skype in Maryland and I have to say they were extremely helpful.
Now we are removing the Raydome and the GPS to send them back to the Service Center.
UPDATE. August 2015 Well the 4 year old Radome has been in for repairs. New Magnatron! It is currently in transit to us. $850 dollars later.
We were able, with the help of cruisers Bob Anderson on Elan and Brian Waters on Hayfu II to connect the chart plotter to the GPS using NMEA 2000 wiring. This works well thankfully. The lesson was.... don't have too much equipment reliant on each other.