Sec.  80.310   Watch required by voluntary vessels.

   Voluntary vessels not equipped with DSC must maintain a watch on 2182 kHz
   and on 156.800 MHz (Channel 16) whenever the vessel is underway and the
   radio is not being used to communicate. Noncommercial vessels, such as
   recreational  boats, may alternatively maintain a watch on 156.450 MHz
   (Channel 9) in lieu of VHF Channel 16 for call and reply purposes. Voluntary
   vessels equipped with VHF-DSC equipment must maintain a watch on 2182 kHz
   and on either 156.525 MHz (Channel 70) or VHF Channel 16 aurally whenever
   the vessel is underway and the radio is not being used to communicate.
   Voluntary vessels equipped with MF-HF DSC equipment must have the radio
   turned on and set to an appropriate DSC distress calling channel or one of
   the radiotelephone distress channels whenever the vessel is underway and the
   radio is not being used to communicate. Voluntary vessels equipped with
   Inmarsat A, B, C, M or Fleet F77 systems must have the unit turned on and
   set to receive calls whenever the vessel is underway and the radio is not
   being used to communicate.

   [ 73 FR 4485 , Jan. 25, 2008]

Distress, Alarm, Urgency and Safety Procedures