Marine Communications – Understanding Your Radio
Today most marine communications are accomplished by using voice radio transmissions. These radio systems are similar to having a conversation on the telephone, but with significant differences that boat operators must understand. Typically, voice radio communications are “simplex,” or one direction at a time – when one person is talking, the second person may not speak. This differs from face-to-face and telephone conversations we are accustomed to where voices may overlap. Simplex communication is the primary reason for many of the procedural regulations for speaking on a marine radio. As a boat operator, using a marine radiophone will be an occasional responsibility. It is important to understand and be comfortable with the proper operation of your vessels marine radio. In this article we will take a look at some standard procedures and protocol as they relate to the proper operation of your boats marine radiophone.
First we must realize that there are several different types of marine radios. On boats, they are frequently MF/HF and VHF-FM, and usually, are identified by the radio’s mode of transmission. Understanding the basic differences of the types of radios and their use will assist you in determining the best solution to your personal/professional boating needs:
- VHF-FM (156‑162 MHz) is used for local, short-range marine communications. Frequencies in this band operate on the line-of-sight (LOS) principle. Effective communications range depends mainly on the height of antennas of both the receiving and transmitting stations, and somewhat on the power output of the transmitting station. VHF equipment is called “line-of-sight radio” because its radio waves travel in nearly a straight line, meaning, if one antenna can “see” another antenna, communications between the two is possible. Occasionally, atmospheric conditions allow VHF signals to bounce or bend in their line of travel, increasing the transmission’s range farther than normal.
- Boats use the MF band typically to communicate when out of VHF radio range. The MF band uses low frequencies, so the ground wave travels along the surface of the earth, permitting communications at distances up to 200 miles during daylight hours. The low frequency also makes communications at much greater distances at night easier. MF and HF radios of any modulation type always have greater range than VHF. The operating range for MF and HF radios can shift as conditions change, and the conditions that affect the operating range will typically vary from hour to hour. As a consequence, communications between two vessels can be lost due to a number of factors, including changing weather.
Next we must understand how to properly use your marine radio phone. The following steps and procedures are the same for either mounted or portable marine radios:
- Check the radio setting: Be certain the marine radio is set on the proper frequency and band width. While on a vessel underway you are required to keep a listening watch on 2182 kHz or channel 16.
- Squelch control: Squelch control blocks out weak signals. Adjust the squelch control until the noise (static) can be heard, then adjust it slightly in the opposite direction until the noise stops. Setting the squelch control adjusts the receiver so only signals strong enough to pass the level selected will be heard and reduces the amount of static noise on the speaker.
- Do not interrupt others: Before beginning a transmission, listen for a few seconds to avoid interrupting other communications that are already in progress.
- Microphone placement: Keep the microphone about 1 to 2 inches from lips. When transmitting, shield the microphone by keeping head and body between noise generating sources (such as engine noise, wind, etc.) and the microphone.
- Know what to say: Before keying the transmitter, know how to say what is going to be said. Keep all transmissions short and to the point. Never “chit-chat” or make unnecessary transmissions on any frequency.
- Speaking: Speak clearly, concisely, and in a normal tone of voice, maintaining a natural speaking rhythm.
- Proper prowords: Use proper prowords, ending each transmission with “over” and the last with “out.” Never say “over and out.”
- Prowords for pauses: In cases where a pause for a few seconds between transmissions is necessary, use the proword “wait.” If the pause is to be longer than a few seconds, use prowords “wait, out.” Do not use “wait one” or “stand by.”
- Messages are not private: Remember, voice transmissions may be heard by anyone with a radio or scanner.