Saturday, March 2

Chapter 16: Review: SSB Channel Designators Explained

Your friends with marine SSB may tell you. . .

To talk local, you want to go on 4A. They sometimes call that 4-alpha. It’s good in the mornings, and 4-alpha on your set is 4-2. Some sets have it as 4-1, but that’s really 4-S. You can look up this channel as 451, which is really 4146. Got it?”

The mysteries of SSB channelization get worse. Did you know that international distress frequency 2182 kHz may NOT be the best place to cry Mayday when you are halfway across the sea?

Single Sideband
And if you call Mayday on Coast Guard working channel 816 or 1205, they could be “duplexing” a weather report and not listening to their input frequency. So WHO do you call in an emergency, anyway, on marine SSB?

And what about making phone calls? Are you really charged $25 just for getting an answering machine? I am happy to report, NO.

So let’s demystify that new marine SSB installation, and compare the channels and frequencies listed in this chapter with what is stored in your SSB’s memory.

ALL THOSE CHANNELS. Marine SSB frequencies are assigned specific channels within the following megahertz regions:

ChannelMHzApproximate Range
2 xx2 MHz100 miles day; 1000 miles night
4 xx4 MHz100 miles day; 1500 miles night
6 xx6 MHz500 miles; 1500 miles night
8 xx8 MHz700 miles day; 2000 miles night
12 xx12 & 13 MHz100 miles evenings; 3000 miles days
16 xx16 & 17 MHzUnreliable evenings; 4000 miles days
22 xx22 MHzDaytime only band, worldwide

Each band of marine frequencies skips off the ionosphere and refracts signals back down to earth at different angles. 2 and 4 MHz come back down relatively close to your vessel. 8 and 12 MHz are excellent for medium-range, day and night, skywave “skip” contacts. On 16 and 22 MHz, skywaves fade out at night, but offer the longest range during daylight hours. The best range usually follows the direction of the sun.

Choose the megahertz range that will skip your signal to the approximate distance you want to reach. 8 and 12 MHz are the favorites during the day, and 4 and 6 MHz are the favorite bands during the night. 2 MHz is clobbered with noise, and you won’t get zip. 22 MHz is too high for reliable daily contacts. Choose 8 and 12 MHz as your “bread and butter” bands.

Marine radio channels are assigned ITU designators. ITU stands for International Telecommunications Union, and assigns commonality to every country’s marine SSB set.

But there are differences between each manufacturer of SSB equipment on how they read out the channels, so stay tuned. More to follow.

Most 2 MHz frequencies have little use even 2182 MHz, the international distress and calling frequency. The range is so limited, you would do better to squawk Mayday on VHF channel 16. Most 2 MHz frequencies go by their actual numerical frequency kilohertz, not by three-digit channel designators. Lucky for us, a kilohertz readout on the radio dial is common among all marine SSB radios in every country.

4 MHz to 22 MHz marine channels are all listed by a three-digit or four-digit channel designator. An example would be marine Channel 401, or marine Channel 809, or marine Channel 1206. These channel numbers, common worldwide, are assigned to pairs of radio frequencies that make up a radio channel. Both the marine telephone companies of the world and the United States Coast Guard and rescue agencies throughout the world operate on frequency PAIRS where they transmit on one frequency, and listen on another. This is called DUPLEX. But you don’t need to worry about the individual frequencies for ship transmit and ship receive because your marine SSB has all of these channels pre-stored in ITU memory. If you dial up marine Channel 808, your set automatically receives on 2740 kHz, and transmits automatically on 8216 kHz. It is pre-stored duplex, so all you need to know is the channel number and what service goes with which channel numbers.

Currently, AT&T* runs the high seas maritime radiotelephone services from three stations that serve this half of the world. However in the future, access will be through station WLO out of Mobile Alabama. AT&T will be limiting the service provided by KMI, WOM, and WOO. From Australia to Africa and everything in between, the AT&T marine operator offers you radiotelephone service on the following channels:

*NOTE: AT&T no longer offers this service

401, 416, 417403, 412, 417410, 411, 416
804, 809, 822423, 802, 810808, 811, 815
1201, 1202, 1203814, 825, 8311203, 1210, 1211
1229, 1602, 16031206, 1208, 12091605, 1620, 1626
1624, 2214, 22231215, 1223, 16012201, 2205, 2210
2228, 22361609, 1610, 16112236
 1616, 2215, 2216 

Choose the channel on a likely frequency that will skip your waves into the particular AT&T maritime services station closest to you. If you’re in the South Seas, you might try Channel 1602 to AT&T coast station in California. If you’re in the Caribbean, try AT&T coast station in Florida on Channel 403. And if you’re sailing to Spain, you might to try AT&T coast station New Jersey on 1203. Otherwise use the WLO Frequencies listed below.

Channel NumberRX FrequencyTX Frequency
Contact Rene Stiegler of WLO radio for information and frequency information packs. PH:(334)665-5110, FX:(334)666-8339, or or

Try tuning these channels in now and listen to the ship-to-shore traffic. You will hear only the shore side of the conversation because the ships are transmitting duplex. Phone calls cost under $5 a minute, with no land-line charges. There is a 3-minute minimum, so once you start gabbing, go for 3 minutes and make it a $15 bill. If you get an answering machine, tell the operator to cancel the call, and you pay nothing. Radio checks with AT&T are free. Calling the Coast Guard through AT&T is also free. What? Calling the Coast Guard through the high seas marine telephone service? Why?

2182 kHz – Distress424Working, Weather, AMVER
Channel601Working, Weather, AMVER
Channel816Working, Weather, AMVER
Channel1205Working, Weather, AMVER
Channel625Working, Weather, AMVER

These are United States Coast Guard weather, AMVER, and working channels and are not necessarily monitored 24 hours a day for a distress call. These are the channels where you will hear automated Coast Guard weather. It is digital speech synthesized, and will sound like someone sitting on a fish hook.

If you need the Coast Guard anywhere in the world, call on the high seas marine operator duplex channels. I guarantee they are listening because they’re looking to make money on an incoming phone call. They won’t make money on a Coast Guard call because they’ll patch you through free. But once your situation is stabilized, the Coast Guard will ask you to switch over to one of their working channels. Suggest a channel near the MHz band you are presently going through the marine operator on. Just look at your radio dial—if it’s reading 1201, then you are on the 12 MHz band. You would suggest to the Coast Guard you can work them on ITU Channel 1205. Switch over, and you will hear their friendly voice.

Did You Know?
The Coast Guard tracks commercial shipping all over the world on a computer in New York—and if you need help or evacuation anywhere out on the sea they can probably
find someone within 300 miles of you and request them to divert and lend assistance. This is part of the Coast Guard’s AMVER program.

Here is where SSB radio manufacturers have split from the normal channeling scheme. Here are the channel designators that SHOULD come up on your marine SSB for ship to-ship safety and routine calls:

4-04125 kHzSafety, “4S”
4-14146 kHzShip-to-Ship, “4A”
4-24149 kHzShip-to-Ship, “4B”
4-34417 kHzShip-to-Ship, “4C”
6-06125 kHzSafety, “6S”
6-16224 kHzShip-to-Ship, “6A”
6-26227 kHzShip-to-Ship, “6B”
6-36230 kHzShip-to-Ship, “6C”
6-46516 kHzShip-to-Ship, “6C”
8-08291 kHz Safety, “8S”
8-18294 kHz Ship-to-Ship, “8A”
8-28297 kHz Ship-to-Ship, “8B”
12-012.290 kHz Safety, “12S”
12-1 12.353 kHz Ship-to-Ship, “12A”
12-212.356 kHz Ship-to-Ship, “12B”
12-3 12.359 kHz Ship-to-Ship, “12C”
12-412.362 kHzShip-to-Ship, “12C”
12-512.356 kHz Ship-to-Ship, “12E”
16-016.420 kHz Safety, “16S”
16-116.528 kHz Ship-to-Ship, “16A”
16-216.528 kHz Ship-to-Ship, “16B”
16-316.534 kHz Ship-to-Ship, “16C”
22-822.159 kHz Ship-to-Ship, “22A”
22-922.162 kHz Ship-to-Ship, “22B”
22-022.165 kHz Ship-to-Ship, “22C”
22-422.168 kHz Ship-to-Ship, “22C”
22-522.171 kHz Ship-to-Ship, “22E”

Not all marine SSB transceivers list these ship-to-ship  channels by the ITU duplex number. Most ICOM marine SSB transceivers list ship-to-ship simplex frequencies by the megahertz band, a hyphen, and numbers 1 through 9. Sometimes the number l and 2 correspond with ship-to-ship A and B channels, yet other times they number up from the safety channel so A now becomes “-2.” But not to worry, just double check the frequency with the ship-to-ship channels and frequencies I have just listed, and go with the frequency.

The safety channels are restricted to navigation. Safety, and weather information, similar to what takes place on marine VHF channel 6. No gabbing on the marine SSB safety channels. The marine ship-to ship channels may also be used by private coast stations so you can talk from ship to shore and bypass the marine operator. Towing and salvage companies, plus marine stores regularly conduct business on ship-to-ship channels 4A, 8A, and 12A. Now go back to the list and double check the frequencies:

4A = 4146 kHz
8A = 8294 kHz
12A = 12,353 kHz

Find these channels on your own SSB radio, and verify the channel number agreeing with the actual ship-to-ship/ship-private coast shore frequency.

If you’re cruising, the Federal Communications Commission offers additional 4 MHz and 8 MHz channels for ship-to-ship communications. This will relieve all of the congestion now found on popular channels 4A, 4B, 8A and 8B. At last—”secret” ship-to-ship SSB frequencies that are perfectly legal under FCC Rule 80.374 (b) (c).


The FCC Rules state, “These frequencies are shared with fixed services, and marine ship-to-ship operation must not cause harmful interference to those other services.” In other words, if you and a cruising buddy land on a frequency and overhear shore traffic complaining about your ship-to-ship communications, switch off that channel in the table above.

Shore stations will continue to monitor their regular frequencies on 4 and 8 Alpha and Bravo frequencies, no charge. But mariners wishing to intercommunicate ship-to-ship on 4 MHz and 8 MHz may now switch to these new, very quiet SSB channels in full compliance with FCC rules. In fact, 4030 MHz is fast becoming the Baja “intercom” channel for mariners with SSB transceivers.

In the Caribbean to Panama canal, try 4054. Hams in the canal, listen 7083 to 7085 lower sideband.