47 C.F.R. § 80.1081 Functional requirements.
Title 47 - Telecommunication
Ships, while at sea, must be capable: (a) Except as provided in §§80.1087(a)(1) and 80.1091(a)(4)(iii), of transmitting ship-to-shore distress alerts by at least two separate and independent means, each using a different radiocommunication service; (b) Of receiving shore-to-ship distress alerts; (c) Of transmitting and receiving ship-to-ship distress alerts; (d) Of transmitting and receiving search and rescue co-ordinating communications; (e) Of transmitting and receiving on-scene communications; (f) Of transmitting and receiving signals for locating; (g) Of transmitting and receiving maritime safety information; (h) Of transmitting and receiving general radiocommunications to and from shore-based radio sytsems or networks; and (i) Of transmitting and receiving bridge-to-bridge communications.
Title 47: Telecommunication
PART 80—STATIONS IN THE MARITIME SERVICES
Subpart W—Global Maritime Distress and Safety System (GMDSS)
Equipment Requirements for Ship Stations
§ 80.1081 Functional requirements.