47 CFR 80.1081 – Functional requirements
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.