GMR 18 HD → GPSMAP 9000

Will a Garmin GMR 18 HD radar work with a GPSMAP 9000?

Yes, through a BlueNet 30 gateway. Garmin lists the GMR HD and xHD2 radar family as compatible with a BlueNet network through the BlueNet 30. Garmin does not list that legacy radar family as a direct BlueNet connection.

What that changes: you may be able to replace the chartplotter without replacing a working GMR 18 HD solely because the new display uses BlueNet. The radar still lives on the legacy Garmin Marine Network side of the mixed network.

The two-device limit matters

The BlueNet 30 has two legacy Garmin Marine Network ports. Garmin says that if more than two legacy devices need the gateway path, those legacy devices must remain interconnected through eligible legacy chartplotter NETWORK ports or a GMS 10 switch before the legacy network reaches the gateway. Garmin also says a mixed network should use only one BlueNet 30 gateway.

Check the GMR HD path in the system checker

What this answer does not prove

It establishes the documented network path. It does not promise that every feature of an older radar behaves exactly like a current radar on a new chartplotter, and it does not replace the radar’s installation instructions. Check current Garmin documentation for the exact radar model before buying hardware.

Primary Garmin sources

• Garmin BlueNet device compatibility table
• Garmin mixed-network / BlueNet 30 rules

Evidence checked: August 23, 2026. Independent site; not affiliated with or endorsed by Garmin.