Adding a chartplotter

Most of the newer Garmin MFD's will interface and share data with the 4212 via NMEA 2000 and Garmin Marine Network (Ethernet) connections and you'd need to run both in any case. Basic nav data, radar, chart and sounder info is compatible but the newer advanced chirp sounder and radar features will not be available on the 4212, only the newer unit up top.

I really dislike going the cheap route and NOT having radar and depth sounder at both helms. If I'm at the lower station, it is because the weather is SO BAD it deems me to be there. Well, if the weather is so bad it deems me to be there, I need Radar and possibly depth worse than ever. Also the IPAD route is not a replacement for a built in chartplotter. In inclement weather the IPAD loses GPS far too frequently, they're not waterproof at all, and the battery only lasts 4 hours on a new one unless it's plugged in. They are great as a secondary unit if you have totally working other stuff that's still adequate such as E120's or Navnet2's. I would install a new unit, perhaps keep your 4212 for now.....then later move it over and install a second new unit.......my preference would be 2 install 2 new units with radar etc etc.

Finding used 4212's is another option. Guessing you could pick one up in good condition for $800 +/-

Crash monsters when you need them (NavNet Trash). F M that they are still on boats at all. Most un-reliable POS that was ever installed on anything.

I have little navnet 2 issues on boats and they're still working. I have far more crashes and issues on E 80's and E 120's than anything. Navnet 2's only seem to have issues if they have voltage spikes and drops.

Crash-Ray??
Seems my ole Pathfinder junk is still pretty cool. RL80 & HSB i/o to my PCs. Zero bugs.
E120 & E120W still hick-up. I have found the Ray-Stuff Switch (hub) causes most problems. RayMarine (Flir) thinks the switch is solid, It's not.
On one boat, RayM swapped all E stuff with E-wide stuff, Same F*ng problem remained. It was the switch as I tried to point out.
Oh, it was a glitch RayM pointed out later.....
Twice later, I've proved the switch should be looked at early in bug fixes..

I finally have some confidence in the E stuff and picking up some equip from e-bay.

I will never rely on that Furno NavNut stuff. Been on to many boats with issues.
On some issues, I can state it was poor installation that caused issues (to be almost fair), but it's still overpriced fancy junk, IMHO.

Ever try to replace the GPS antannae for a pathfinder or E120???? Requires switching all sorts of crap.

Still run the old RN3x0 GPS stuff. Works very well. E crap still uses the SeaTalk I lingo well also.
Just not Pathfinder HSB (1 or II).

All else plugs rite into the Cat5 net without the extra hardware required for old Pathfinder HSB (1 or II) I/O.

I'm a fan of solid equipment. Not worried how old it is.
I fav boat still has DECA 101.
When it works, don't kick it (to hard).

You're going to need a chartplotter more than ever from Fl to NJ. I would just install it. Garmin, Furuno, and Simrad in that order.......Raymarine is garbage.

The Garmin App is more readable and better than the navionics app. BUT, you have to click on the charts you want and download them, it doesn't download all of them automatically.

I do not.

While I'm fairly certain it will work just fine its best to call Garmin tech support to be safe.

I installed a a new 3 display system with the Fantom radar on a big Mangusta last year. They had an older 5000 series display that we kept as a backup and it was able to communicate with the new hardware with no issues.

One thing that is really helpful is installing a port expander and connecting everything to it instead of using the network ports on the displays to piggyback. If one display goes out, radar and sounder will still be available on the others.