Your VHF marine radio could turn out to be the single most important piece of equipment that saves your life in an emergency. After all, a marine radio is the most effective way to call the Coast Guard for help. But if not used properly, precious time may be wasted. Marine radio etiquette was developed to help make transmissions easily understood--whether by emergency personnel or just by the launch operator at your club or marina.
Coast Guard Regulations
While recreational boats under the length of 20 meters are not required to have a marine radio on board, most mariners choose to do so. When the radio is in operation but not transmitting, it must be monitoring the hailing and distress channel, Channel 16. A marine radio should never be used on shore except by such stations as yacht clubs or bridges, who must communicate with boats. Mayday calls that are not genuinely related to an emergency on the water (for example, when life or property is in immediate peril) are strictly forbidden.
Keep your marine radio tuned to channels 16 or 9 at all times (Channel 16 is the channel on which other vessels will initially try to contact you and the channel on which the Coast Guard issues weather alerts and other transmissions). Channel 16, which is monitored by the Coast Guard at all times and is the channel on which you should call the Coast Guard for help, is used for hailing--for example, if some other boat needs to contact you or if you need to hail another boat.
Often the Coast Guard will ask mariners to assist in search-and-rescue operations by putting out a bulletin with the description of a vessel in distress and asking mariners to keep "a sharp lookout" and to report all sightings. Also on channels 9 and 16 are severe weather alerts and announcements of hazards to navigation.
Conduct radio checks on Channel 9, not Channel 16. A radio check is when a transmission is sent out saying, "Radio check on Channel 9, radio check on Channel 9, please (and state your vessel's name and location), over." Other mariners who receive the transmission may call back with "Radio check loud and clear, (their location), over," to which you should reply, "Radio check thank you, over and out." This lets both parties know that their marine radios are functioning properly. "Over and out" signifies that the sender is through with that conversation and is switching back to monitor Channel 16.
Do not use obscene language, do not transmit music and do not transmit subversive messages. These are all forbidden by the Coast Guard. Do not let children use your marine radio unless closely supervised. Do not ever use Channel 16 to converse with any other station. Do your hailing on Channel 16, and then when contact is made, establish a working channel other than Channel 16.
While the radio is turned on, it will monitor whatever channel is selected. To hail another station (such as another boat, or a marina or a bridge), depress the "Microphone" key and say two or three times the name of the station you are calling, followed by "This is (your vessels name) on 16 (or the channel you are using), over." Then release the key and wait for a response. By saying "over" you are indicating that you are waiting for a reply. When contact is established, a working channel should be agreed upon. This method of hailing is also used to contact the Coast Guard on Channel 16, but if loss of life or property is imminent, the transmission should start with "mayday, mayday, mayday."
Anytime you use your marine radio, be aware that there are others trying to send their own messages on the same channel, and so care should be taken not to "step on," or override, their transmissions. Before depressing the "Microphone" key, listen to make sure others have finished with their transmissions.
Channel 16 is the hailing and distress channel only and is monitored all the time by the Coast Guard. Recreational boaters are cleared to use channels 67, 68, 69, 71, 72 and 78a for working channels. Most commercial vessels and bridges monitor Channel 13.