Actually the Solstice has 8 UHF Channels, four are known
Ch.01 Bridge Ops 457.5250 R 173.8 Hz
Ch.02 ?? 457.5500 R 186.2 Hz
Ch.03 ?? 457.5750 S 118.8 Hz
Ch.04 ?? 457.6000 S 203.5 Hz
Other channels are limited use, and likely found during Lifeboat drills and/or Shore Exc
Most of their internal comms are on the 7900-series Cisco WiFi VoIP phones, but most security and tender operations are on analog 457.5250 PL 173.8.