You are sailing to the farthest reaches of an isolated bay when you strike an unchartered, submerged object. You begin taking on water. No one is around. If you had a radio, you could call for help.

Motoring along the river, one of your passengers begins convulsions. You know you must contact medical authorities immediately, but you are without a radio. With a radio, medical help might be only a radio call away. Without one, it may be hours before you are able to get to a medical facility.

Investing in a good Very High Frequency FM (VHF FM) radio is the smartest purchase. A VHF radio has certain advantages such as:

• Good quality transmission.
• Strong signal.
• Channels reserved for distress calls.
• Continuously monitored frequencies. 

There are 104 VHF channels designated for marine service. Of this number, 54 are designated exclusively for use in the waters of the United States. The most common channels and their purpose are listed below:

• Channel 16 (156.8 MHz) - This is the most important channel on the VHF band. This is the distress, safety, and calling frequency which the Coast Guard monitors continuously. All vessels equipped with VHF radios must keep their radios tuned to channel 16 so they can assist if an emergency is near. Vessels may initiate contact with each other but must shift to a working frequency to carry on a conversation (e.g., Motor vessel Albatross, this is sailing vessel Mother Goose, AB-1234, on channel 16, switch and answer Channel 68). Use Channel 16 for only bona fide emergencies.
• Channel 22A (157.1 MHz) - This channel is the primary working channel of the Coast Guard. It is used for communications between the Coast Guard and the maritime public, both recreational and commercial. Severe weather warnings, hazards to navigation, and other maritime safety warnings are broadcast on Channel 22A.
• Channel 13 (156.65 MHz) - The bridge to bridge or "piloting" channel. Used for communicating navigation information between ships. Strictly used for navigation purposes by commercial, military, and recreation vessels at locks, bridges and harbors.
• Channel 6 (156.3 MHz) - The ship to ship frequency used for safety related communications. Not used for ordinary operational navigation or personal communications. 

• Mayday - Is a request for immediate assistance. LISTEN! DO NOT TRANSMIT! Determine if you're in a position to help. If not, maintain radio silence. "Mayday" identifies an imminent, life-threatening emergency.
• Pan-Pan - (pronounced pahn-pahn) is used when the safety of a boat or person is in jeopardy. Man-overboard messages are sent with the Pan-Pan signal.
• Securite - (pronounced say-cure-e-tay) is used to pass navigation information or weather warnings. 

If you have a radio and you are under way, you are required to monitor Channel 16. Mayday takes precedence over all other transmissions. If you hear a Mayday, remain silent and listen. Take down the information being passed. If the Coast Guard or other rescue authority responds, maintain silence and listen but do not respond.

However, if there is no response, take action. Try raising the distressed vessel over the radio. Gather more information, especially the position. Attempt to raise the Coast Guard while traveling toward the vessel. Sometimes the Coast Guard may not hear the distressed vessels transmissions, but can hear another vessel near the scene; therefore, call the Coast Guard again, just in case. If you raise them, give them the information you have and follow their instructions. If you do not, attempt to assist the other vessel to the best of your ability without placing yourself in danger. 

If you have an imminent life threatening emergency, transmit on Channel 16:

• 1. MAYDAY, MAYDAY, MAYDAY!
• 2. This is (name of boat three times, call letters once).
• 3. Repeat once more, "MAYDAY", (your boat's name)
• 4. Now report your position (give as accurate a position as possible).
• 5. Report the nature of your emergency.
• 6. Report the kind of assistance desired.
• 7. Report number of people on board and condition of any injured.
• 8. Description of the boat and seaworthiness. Then wait for a response. If there is none, repeat the message.

You must have a Ship Station License for your radio before operation. An Operator's Permit is only required if you dock in a foreign port. To obtain forms and additional information contact the FCC at (202) 632-FORM.