Section 80.93 - Hours of service(a)All stations. All stations whose hours of service are not continuous must not suspend operation before having concluded all communication required in connection with a distress call or distress traffic.(b)Public coast stations.(1) Each public coast station whose hours of service are not continuous must not suspend operation before having concluded all communication involving messages or calls originating in or destined to mobile stations within range and mobile stations which have indicated their presence.(2) Unless otherwise authorized by the Commission upon adequate showing of need, each public coast station authorized to operate on frequencies in the 3000-23,000 kHz band must maintain continuous hours of service.(c)Compulsory ship stations.(1) Compulsory ship stations whose service is not continuous may not suspend operation before concluding all traffic originating in or destined for public coast stations situated within their range and mobile stations which have indicated their presence.(2) For GMDSS ships, radios shall be turned on and set to proper watch channels while ships are underway. If a ship has duplicate GMDSS installations for DSC or INMARSAT, only one of each must be turned on and keeping watch.(d)Ships voluntarily fitting GMDSS subsystems. For ships voluntarily fitting GMDSS subsystems, radios shall be turned on and set to proper watch channels while ships are underway. If ship has duplicate GMDSS installations for DSC or INMARSAT, only one of each must be turned on and keeping watch.(e)Other than public coast or compulsory ship stations. The hours of service of stations other than those described in paragraphs (b), (c), and (d) of this section are determined by the station licensee.51 FR 31213, Sept. 2, 1986, as amended at 68 FR 46960 , Aug. 7, 2003