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Idiot's Guide to Marine SSB

Despite several advances in offshore voice communications such as satphones, marine single sideband (SSB) isn't going away anytime soon. That's because SSB, unlike satphones, allows an unlimited number of people to listen to a transmission at the same time.

As such, SSB is the only way to go for the various regional cruising nets, such as the Baja, Sonrisa, Chubasco and Southbound. It means that when Don Anderson of Summer Passage, for example, transmits his latest weather forecast, anyone who wants to can listen at the same time. When someone has a question about the forecast, everyone can hear the question and Don's response.

Marine SSB is also perfect for cruising events such as the Baja Ha-Ha, the Caribbean 1500 and the Atlantic Rally for Cruisers. "While the Ha-Ha doesn't require SSB radio," advises the Grand Poobah, "most boats do have them. They're good for safety — but fun, too. The folks with SSBs are able to actively participate in all the roll calls, weather and fishing reports, and other fleet news. Over a period of nearly two weeks, personalities develop over the radio, and an even greater sense of community is established."

In racing events such as the TransPac, Pacific Cup, and Singlehanded TransPac, it offers more than just straight communication. "Thanks to marine SSB, our 1700 hour reports and discussions maintain the racing camaraderie and fun," notes Jack McGuire, KG6CJN, communications chairman of the '08 Pacific Cup race.
Although not the subject of this article, the other significant benefit of SSBs is that, when used with a Pactor modem and SailMail, they allow for the transmission and reception of brief emails while offshore.


You don't need to pass a Ham radio operator's test to use a marine SSB. All that's required is a valid Ship Station license and a lifetime Restricted Radiotelephone Operator's permit. No testing required! The Ship Station license is good for 10 years and is non-transferable. If you're good at dealing with online government forms, you can apply for a license at If you're not so good at it, or don't want to take the time, my lovely wife Suzie will be happy to help for a fee: (714) 549-5000.
How does Ham (amateur radio) differ from SSB? If you're new to long distance marine radio, I suggest not even worrying about it. Although I run the Radio School and some of the income comes from teaching students how to use Ham radio and pass the test, I generally discourage new SSB operators from taking that step right away. Get the no-test license for SSB radio, become familiar with the procedures and protocols, and use it for a few months. If you find that you're one of the very few cruisers who talks on the radio so much that SSB frequencies aren't adequate, then look into Ham radio. Or if you're going to the South Pacific, where there's lots more traffic on ship-to-ship channels, you might consider eventually moving up to Ham status. But generally speaking, it's really only for serious radio buffs.
By the way, there is nothing to prevent folks with SSB radios from listening on Ham frequencies, and indeed, there are some helpful Ham-only weather broadcasts. If you're worried that you might accidentally stumble onto a Ham-only frequency, start transmitting, and really piss off the 'radio police', fear not. SSB radios that are capable of working Ham frequencies come 'locked' from the factory. Some can only be unlocked using software, while others can be unlocked by simply pressing three keys at the same time. In cases of genuine emergencies, Ham frequencies can be used by people who don't have a license.

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How Far on What Bands?

A marine SSB system operates on marine radio spectrums called shortwave, medium frequency and high frequency — 2 MHz-26 MHz. This radio spectrum is shared with hundreds of other radio users including shortwave broadcasts, Ham radio, FEMA, the American Red Cross, and long-range aircraft.

Radio signals within the SSB shortwave spectrum refract off the ionosphere and come back to earth hundreds or thousands of miles away without the need for communication satellites and/or ground stations. Each marine SSB radio frequency band has a very predictable skywave bounce bulls-eye. If you choose a band that's too high, your signal will skip over the other station. If you choose a frequency that's too low, your signal won't go far enough to reach.

The following is a good guide for choosing the band of frequencies that will target your first skywave bounce:

2 MHz 200-400 miles
4 MHz 400-600 miles
6 MHz 600-1,200 miles
8 MHz 800-1,600 miles
12 MHz 1,200-2,400 miles
16 MHz 1,600-3,200 miles
22 MHz 2,200-4,000 miles plus
26 MHz unpredictable during our solar cycle minimum

Pop Quiz #1: You are in San Francisco and you want to talk with your buddy who's on his boat 1,200 miles away in Cabo San Lucas. Which band on marine SSB might you choose?

Answer: Because 4, 6, and 8 MHz would likely fall short on the first radio signal bounce, 12 MHz and 16 MHz would likely be your best choices

The thing that usually drives new SSB operators nuts — and I know that it still irritates the Ha-Ha's Grand Poobah — is that SSB radio frequency/channels are so different from VHF, FM, television, and almost every other kind of channel. On VHF, for example, channel 72 is channel 72. On television, channel 7 is channel 7. What could be more simple?

Certainly not SSB radio. Get this: while 4146 is always 4146 on SSB, it's also known as 4A, and sometimes the designator 4-1. In addition, depending on the individual radio, it's often channel 35 or channel 77, and could also be some other channel. That's right, depending on what radio you bought and when, and who might have customized the user channels, channel 35 and channel 77 may or may not be 4146 and vice versa. And, of course, it might also be channel 63 or 147 — or a bunch of other channels.

The best way to get to 4146 is to just tune to 4146. The problem is that you may have to do a lot of knob turning, which can be annoying. In order to eliminate unnecessary wrist injuries from knob turning, some manufacturers 'channelized' the more popular frequencies. That is, they assigned specific channels to specific frequencies. For example, the Icom SSB radios of several years ago assigned channel 35 to frequency 4146 (aka 4A and 4-1). Unfortunately, in later radios, they decided to assign channel 77 to 4146 (aka 4A and 4-1). In addition, some retailers created custom 'user channel' packages, which gave yet another channel designation to 4146.

How did it all come to this? SSB operators used to have to spin the frequency knob like crazy to find anyone because there are more than 1,000 SSB frequencies — only a very few of which will ultimately be of interest to you. (More on that later.) As a result, most modern marine SSB transceivers — a fancy name for a combined transmitter and receiver in one black box — have nearly 700 pre-stored duplex channels (specific frequencies designated as channels for easier access). After all, what's easier: dialing through 1,000+ frequencies or 700 channels?

Nonetheless, you could spin your SSB dial all day long and you'd probably still hear nothing — except for WLO, the excellent radiotelephone station located in Mobile, Alabama. If you want to pick up something, look for on-the-hour weather and traffic reports on the following International Telecommunications Union (ITU) three- and four-digit designators: 405, 417, 805, 824, 830, 1209, 1212, 1226, 1607, 1624, 1641, 1807, 2237 and 2503. If you punch in 1607 on the hour, you'll get traffic lists and weather broadcasts from powerful WLO. The U.S. Coast Guard also broadcasts voice weather reports on ITU channels 424, 601, 816, 1205, and 1625.

Because SSB radios are more complicated than VHF radios, you might initially have a little trouble punching in the three- and four-digit ITU channels and/or the actual frequencies.

Icom America, Furuno, and SEA are the last remaining SSB manufacturers, and of the three, Icom is the undisputed leader when it comes to equipping recreational vessels with marine SSB gear. To help North American sailors more easily call up relevant ship-to-ship, Coast Guard, weather facsimile, Ham and marine telephone stations, Icom has pre-programmed 160 "favorite channels" — channels 1 through 160 — into a memory circuit titled 'User Channels'.

If you have an Icom 802 and tune to channel 77, you'll find that you'll be on frequency 4146 (aka 4A). And if you tune to channel 135 on an 802, you'll find yourself on frequency 3968, which is home to the Sonrisa Net at 7 a.m. Pacific Time in the winter. It will even show 'Sonrisa Net' on your screen, even though the Sonrisa Net only uses that frequency a few hours each day.

Your radio will no doubt also have a toggle for 'channel/frequency'. As you move it, the display will switch back and forth from, say frequency 4146 to channel 77 — assuming, of course, that 77 has been assigned to 4146 on your particular radio.

Most Icom marine SSBs may be tuned off of a memorized channel, to hear a weather report on a frequency that has recently moved. Press the 'CL' button — the channel knob now goes into frequency changing — and turn the knob in tiny steps. You may need to do a lot of knob twirling to get to some of the new weather nets. Be sure to push 'CL' again to get out of this mode.

Take this opportunity to run all the user channels on your radio, and make a list of what frequencies/stations they refer to. As mentioned, if you have a newer Icom 802, it's very likely, but not certain, that you have the same channel/frequency combinations as owners of other new Icom 802s. But if you have an older Icom model, or perhaps had a custom user channel package installed into your 802, I'd recommend that you have an authorized Icom dealer come down and give you the most recent user channel package. He'll just plug his computer into the front of your radio and download the new stuff. It shouldn't take more than 15 minutes and will sync you with the majority of other SSB radios.

Latitude 38's
Favorite SSB Channels

When cruising Mexico, these are the only channels you'll
really need for calling ship-to-ship or ship-to-California.

Channel Designator
Latest ICOM
Frequency kHz
4146 kHz USB
4149 kHz USB
8294 kHz USB
8297 kHz USB

If you look at the table above, you'll see Latitude 38's favorite SSB channels that will help you better understand that each channel has a specific purpose. You'll notice there aren't 700 of them. That's because you can use only 33 primary channels. And for cruisers in California and Mexico, you'll almost certainly use just five of them: 4A, 4B, 4C, 8A and 8B. That's not many, but you'll rarely have trouble finding an open channel. (There are an additional 49 secondary channel/frequencies on the 4 MHz and 8 MHz bands that you can use if they aren't being used at the time, but if you're just starting out, you don't need that additional confusion.)

The main thing to do is play with your user channels/frequency combinations so you become familiar with them. It won't take long. If you find that your channels are out of sync with most other folks' SSBs, you might want to change yours to match theirs. Depending on how technical you are, you may or may not need assistance.

Calling for Help over the SSB

There are six Coast Guard Global Maritime Distress and Safety System (GMDSS) channels/frequencies:

2182, the distress channel
4125 (4S)
6215 (6S)
8291 (8S)
12,290 (12S)
16,420 (16S)

The Coast Guard and other international rescue agencies monitor them 24 hours a day. U.S. Coast Guard monitors out of Hawaii, Guam, Alaska, San Francisco, New Orleans, Miami and Norfolk.

Warning! Remember, different bands have different ranges. If you make an emergency call on 2182 when you're halfway between Mexico and the Marquesas, it's very unlikely anyone will hear you. If you check the earlier chart, you'll see that you'd actually want to transmit on 12,290 (12S) where the range would be 1,200 to 2,400 miles.

SSB in an Emergency

Marine SSB has been allocated hundreds of international channels, some of which are closely guarded by the U.S. Coast Guard and worldwide rescue agencies. They are prepared to act immediately on any received mayday or call for medical assistance. The Coast Guard maintains 24/7 distress radio guards on the following frequency bands:

2.182 MHz 0-400 miles
4.125 MHz 400-800 miles
6.215 MHz 600-1,200 miles
8.291 MHz 800-1,600 miles
12.290 MHz 1,200-2,400 miles
16.420 MHz 1,600-3,200 miles

Checking Your SSB Reception and Transmission

As a new user, even if you get some meaningful reception as you dial around the channels, you'll probably still wonder if your SSB is working as it should. One way to find out is by trying to pick up the time signals at 10 and 15 MHz and WWV, which provide a continuous signal for a ready reference. If you're still at the dock and plugged in, you may find that turning off the shore power battery charger will make a huge difference in your reception. Ditto for refrigeration, fluorescent lights, and inverters.
If you're not sure that you're transmitting, you can tell a lot by looking at the LCD display on the face of your radio. First, push the 'TUNE' button, at which point the radio should briefly transmit a low power signal to tune the automatic antenna coupler. Do this on any 6 MHz channel as long as there is no traffic on it. The word 'TUNE' should flash a couple times on the LCD screen, and then stay up on the screen when the radio cycles back to receive. Still see the word 'TUNE'? This is good. However, if the word 'THRU' comes up, or 'HI SWR', you've got problems. It's probably time to bring in an NMEA-qualified marine SSB specialist to find out what's wrong between your radio and your tuner.

Assuming you do get 'TUNE', it's time to pick up the mic and try a short transmission. After doublechecking that the frequency is clear, key the mic, and speak directly into it saying "FOOOOUUUUR." The mic should be touching your lips when you do this. If the following things happen, it suggests that your transmission is good and powerful:

1) The LCD bar graph goes full scale.
2) Your cabin lights dim slightly.
3) The instrument indicator lamps glow.
4) The bilge alarm squeaks.
5) The house battery drops about half a volt.

It's perfectly normal for instrument panel lights to glow and bilge alarms to squeak when a powerful 100 watts are coming out of your SSB. But be sure to doublecheck that the LCD transmit indicator shoots across the screen when you say a very loud "FOOOOUUUUR."

A potentially more dangerous way to test the transmit power output is with a small fluorescent tube at night. Ask your first mate to hold the glass tube against the insulated backstay antenna or the big white whip. Caution! Be sure they don't touch the backstay with their fingers or other parts of their body, as this could result in a nasty burn or worse. Say the magic word ("FOOOOUUUUR") once again, and the tube should instantly light up. The glass must actually be touching the radiating antenna or antenna lead-in single wire for this to happen.

If the cabin lights dim, the head flushes, numerous bilge alarms go off, and the fluorescent tube lights up, chances are excellent that you're putting out 100 watts. But are they clear watts? Only a radio test with another SSB user can determine that, so ask someone else in the marina to dial in a common ship-to-ship channel, such as 6224, and run your radio check. This will be a good test for a nice, clean signal.
If your test partner reports that your sound was garbled, and you've just added a new email modem to your rig, temporarily disconnect the wire going from the back of your SSB to the computer. If your voice is now clear, these additional wires are the problem. Your local marine electronics specialist carries snap-on filter chokes, which may resolve the garbled voice problem.

A good test for the range of your radio is with me! I'm happy to offer Latitude readers free, on-the-air radio checks on an appropriate SSB frequency that will agree with the approximate range between your station and mine here in the Newport Beach area. If your boat is in the Bay Area, we will likely use 8 MHz. If you are local, we'll go with 4 MHz, and if you're down in Cabo, we'll probably choose 12 MHz. Call me at (714) 549-5000 on weekdays and we'll find a nice quiet channel for our radio check.

Another great way to test your marine SSB transmit-and-receive capability is with weather guru Don Anderson on his marine SSB Amigo Net. He begins at 1415 hours Zulu (UTC) on 8.122 MHz, upper sideband. If you have the latest frequency load from Icom America, it's already stored in memory as channel 105. If you don't find it in memory, you will need to break out the instruction book and learn how to program a new frequency into your user-programmable frequency 'bin'. It's not hard, but if you've never done it before, it can be a mystery. If you have problems while in San Diego you might want to call in a marine electronics tech familiar with marine SSB equipment. Try Shea Weston of Offshore Outfitters at (619) 225-5690 or (619) 980-6217 (cell).

Two Final Tips

First, if you sent your Icom 802 to the factory to get the 'clipping' problem fixed, you'll note that there are two places to plug in the antenna. One is for the DSC antenna, the other for your SSB antenna. Unfortunately, they are not clearly labeled, and a number of people have plugged their SSB antenna into the wrong port. As a result, transmit and receive range are minimal. You'll see an antenna tuner error if plugged into the wrong jack. Set it up temporarily and test it with time signals.

Second, to avoid violating FCC rules, Icom is very conservative regarding output power and how wide the signals are. I think they're too conservative. If you get that voice compression software unlocked, your radio transmissions will boom out with a commanding signal like Voice of America. The software upload is available only from authorized Icom dealers. They can come aboard and plug it into your radio, as well as the most recent 'user channel' update. It usually takes just 15 minutes.

Subscribe/contribute to Latitude 38 sailing magazine here.

- gordon west

Also see Latitude 38's Guide to Marine Nets.