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CPV550
24. CHANNEL ASSIGNMENTS
Tables on the following columns list the VHF Marine Channel assignments for U.S.A. and
International use. Below are listed some data about the charts.
1. VTS. Where indicated, these channels are part of the U.S. Coast Guard’s Vessel Traffic
System.
2. Alpha channel numbers, that is, channel numbers followed by the letter A (such as
Channel 07A) are simplex channels on the U.S.A. or Canadian channel assignments
whose counterparts in the International assignments are duplex channels. International
channels do not use “alpha” numbers. If you call the Coast Guard on Channel 16, they
will sometimes ask you to “go to channel 22 Alpha.” This is a channel assigned to U.S.A,
and Canadian Coast Guards for handling distress and other calls. If your radio is set for
International operation you will go to Channel 22 instead of 22A, and will not be able to
communicate with the Coast Guard. To use Channel 22A, your radio must be set for
USA or Canada operation, usually by a U/I/C (USA/International/Canada) control or
combination of controls. Channel 22 (without an “A”) is an International duplex channel
for port operations. Some radios indicate an “A” adjacent to the alpha channels on the
display; on others “alpha” is not indicated but the proper channel is selected based on
the U/I/C setting.
3. Bridge-to-Bridge channels (for example, Channel 13) are for use by bridge operators
on intercoastal waterways and rivers. It is also used by marine vessels in the vicinity of
these bridges for navigation and for communicating with the bridge operators. Note that
a limit of 1 Watt is specified for these channels. See page 28 for additional information.
4. The S/D column on the chart indicates either S (simplex) or D (duplex). Simplex means
transmitting and receiving on the same frequency. Only one party at a time can talk,
unlike a telephone. Be sure to say “over” and release your microphone push-to-talk
switch at the end of each transmission. Duplex operation involves the use of one
frequency for transmitting and a separate frequency for receiving. On channels
specified as duplex on the charts, correct mode of operation is established automatically
by your radio when you select a channel; you cannot change the mode. And you still
must release the push-to-talk switch after each transmission in order to listen to the
radio.
5. Channels normally used by recreational boaters are those that include the term “non-
commercial” in the Channel Use column of the chart. Some of these are shared with
other users and some are used only in certain geographic regions.
6. Marine vessels equipped with VHF radios are required to monitor Channel 16.
