In general the IMO states that the receiver should be tuned throughout the bands between 1605 KHZ and 27.5 MHZ. This tuning should be either continuous, or by incremental steps, or by selection of a number of spot frequencies.
The following frequencies should be readily accessible to the operator.
For Radio Telephony, the carrier frequencies are 2182.0 KHZ, 4125.0 KHZ, 6215.00 KHZ, 8219.00 KHZ, 12290.00 KHZ, and 16420.00 KHZ.
For NBDP, the carrier frequencies are 2174.50 KHZ, 4177.5 KHZ, 6268.00 KHZ, 8376.5 KHZ, 12520.00 KHZ, and 16695 KHZ.
For DSC (Digital Selective Calling), the frequencies are 2187.50 KHZ, 4207.5 KHZ, 6312.00 KHZ, 8414.5 KHZ, 12577.00 KHZ, and 16804.5 KHZ.
The transmitter should also be able to transmit all the above frequencies allocated to the maritime mobile service in the frequency band between 1605.00 KHZ and 27.5 MHZ. The same condition as stated above will apply to the transmitter.
Radio Watch Keeping at Sea (SOLAS Regulation):
All ships while at sea should keep a continuous watch on the following frequencies to receive any distress signal from another ship or to receive any distress and safety alert form shore based services. Keep continuous watch on
- VHF DSC channel 70
- DSC MF 2187.50 KHZ (for receiving ship's distress signals and safety alerts)
- DSC distress and safety frequencies 2187.5 KHZ and 8414.5 KHZ and also on at least one of the distress and safety HF DSC frequencies 4207.5 KHZ, 6312 KHZ, 12577 KHZ,Or 16804.5 KHZ according to the time of day and the geographical position of ship relative to the nearest DSC coast station.
Credits: IMO regulation and SOLAS regulation