Final answer:
The preferred channel to communicate with the US Coast Guard on a marine VHF radio, except for distress and safety calls, is channel 16.
Step-by-step explanation:
The preferred channel to communicate with the US Coast Guard on a marine VHF radio, except for distress and safety calls, is channel 16. Channel 16 is known as the international calling and distress frequency and is monitored by the Coast Guard and other vessels in case of emergencies. It is important to note that channel 16 should only be used for emergencies and not for routine communication.
The preferred channel to use for non-distress and non-emergency communication with the US Coast Guard on a marine VHF radio is Channel 16. This channel is primarily used for hailing and distress calls, but it can also be used to establish communication before switching to a working channel for further conversation. However, for routine communications, the US Coast Guard often monitors Channel 22A. This is the channel mariners are typically directed to once initial contact is made on Channel 16 if the situation is not an emergency. Mariners should always check the current guidelines for VHF radio use in their area, as channels and procedures can sometimes change.