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We are often asked by those planning to set sail and go voyaging if we can help them sort through the myriad of details about voice and digital communications aboard. Given the regularity of these requests, we thought it good to try to demystify the subject of high-frequency (HF) radio communications aboard a cruising yacht with an emphasis on the comparison of marine versus amateur frequencies.
Most cruising yachts today carry three radios that are important for ship-to-ship and ship-to-shore communications. These are: a very high frequency (VHF) transceiver for voice communications over a short distance (<20 nm); an Automatic Identification System (AIS) receiver or AIS receiver/transponder for digital communications using VHF frequencies of a ship’s identity, position, course, speed, etc.; and a high-frequency single sideband (HF SSB) transceiver for long-range digital and voice communications.

VHF radio waves are used in VHF radios and AIS units. The frequency of 156.800 MHz is the VHF frequency of channel 16, the agreed-upon international distress, safety and calling channel that is programmed into all marine VHF radios. AIS units use VHF frequencies of 161.975 MHz and 162.025 MHz.

HF, by contrast, refers to frequencies in the range of 3 MHz to 30 MHz. These frequencies, under certain circumstances, can be used to propagate radio waves over very long distances, even completely around the globe, which is why HF radio is an important communications conduit for yachts at sea. In order to communicate on these frequencies, most yachts today use a “single sideband,” or SSB, radio that both receives and transmits — a so-called “transceiver.” SSB is simply the way in which the wave is transmitted that results in a tightly compacted signal, which allows the radio wave to travel thousands of miles.  

To complicate matters a bit, in the HF frequency range of SSB radio communications, certain frequency ranges are allocated for marine use (thus called “marine bands”) while other frequency ranges are reserved for amateur radio usage (generically called “ham bands”). Both bands host voice and digital communications. Licensing for each band is different, as are the rules, so by becoming licensed for and using both radio frequency bands, a yacht and its crew can effectively maximize the available HF radio communications bandwidth.

As for radios, most marine radios can be operated legally in both the marine and ham bands, which is called dual usage. However, modifying a ham radio to operate on marine bands may not be legal; your local radio dealer can certainly advise you. Bottom line: the best HF radio to have aboard will operate on both bands at either 100 or 150 watts of power. Aboard Carina we have a dual-usage or open ICOM 710RT marine transceiver.

Marine radio: To legally operate an HF radio on marine bands in international waters, you are required to obtain a restricted radiotelephone operator permit (RR) for yourself, as well as a ship’s station license (also known as a Ship Recreational or Voluntarily Equipped License, or SA) for your non-commercial yacht. Visit the universal licensing system page of the Federal Communications Commission’s website at for online filing options.

You will first need to file Form 160 in order to obtain an FCC registration number (FRN). Once you have an FRN, you can apply for both the RR and SA with separate copies of Form 605, one for each license; the remittance form is No. 159.

The operator permit is good for the lifetime of the applicant and certain restrictions apply. The station license is good for 10 years and is easily renewed on the FCC’s website up to 90 days before it expires. If you do not renew before the license expiration date, the license expires and cannot be retrieved. You must then file a new application. A new ship’s station license and call sign will then be issued.

Philip DiNuovo at his laptop in Carina’s nav station where he uses both SailMail and Winlink programs for handling email traffic via HF SSB.

Philip DiNuovo

The station license for our vessel Carina is designated by the call sign WCZ5553, while Carina’s maritime mobile service identity (MMSI) number of the same license (used for AIS) is 366880620. This license allows us to legally operate Carina’s SSB on marine bands while in international and foreign waters. In fact, many countries we have visited required us to give them our marine call sign as part of the data collected at an official check-in. 

So it follows that when a yacht communicates using an HF radio on designated marine bands, the appropriate call sign is that of the ship’s station license. Thus, on the marine band radio network such as the “Amigo Net,” a Mexico-based net with a large attendance, radio protocol would dictate that we hail the net as “Carina” and sign off as WCZ5553.

On marine HF bands, special permission is required for a land-based station to use the frequencies. Usually only government agencies, like the U.S. Coast Guard, or designated ship-to-shore traffic providers such as ShipCom or Sailmail can transmit/receive on marine bands from land-based radio stations. There are some rare exceptions to this generality — for example, the incorporation of specially licensed weather providers such as the late Don Anderson of Summer Passage Radio and David and Patricia Sapiane of New Zealand’s Gulf Harbor Radio (

Amateur or “ham” radio: By contrast, ham radio involves non-commercial, non-broadcast communications between individual radio operators worldwide. Thus the license is “mobile” and moves with the person. This is why the shoreside operators who support cruising yachts with voice or digital communication from their homes operate on ham bands. In other words, it isn’t their boat or their RV or their “shack” at home that is licensed, but the amateur operators themselves. In order to be licensed, individuals must pass certain written examinations that are dictated by the FCC.

The most common amateur radio bands used for maritime mobile nets are 7 MHz and 14 MHz (or the 40 meter and 20 meter bands, respectively). To operate legally in these bands, at least one person aboard a yacht — the radio control operator — must hold a General class ham license or above. A non-licensed individual may operate the radio but only under the direct supervision of a licensed person. Because an amateur license is issued to an individual, when a ham radio operator on a yacht calls into a ham radio net, he or she uses their amateur radio call sign. Thus, when we call the Pacific Seafarer’s Net that operates on 14.300 MHz USB — a ham band — the protocol is to hail the net as WZ7LL for Leslie, or K7PAZ for Philip, and not as WCZ5553 for yacht Carina. The fact that we are operating from the yacht Carina is incidental to the fact that we are licensed amateur operators.  

Most countries, including the U.S., require that individuals pass a test of competency to obtain a license to legally operate a radio on amateur bands. The FCC does not conduct amateur license tests directly but uses volunteer examiner coordinator groups (VECs) that provide the infrastructure for volunteer examiners to conduct testing. The VEC group is the liaison to the FCC. There are 14 FCC-certified VEC groups operating today, including the American Radio Relay League and W5YI. The U.S. is a member of the International Telecommunications Union of the UN (ITU), so a U.S. amateur radio license is recognized by the 193 ITU member states around the world.  

HF radio communications
Voice: An HF radio cannot be effectively replaced by a satellite telephone, though the latter is a valuable communications tool too. Satellite telephone communication depends on radio communications between the individual with the handset, the satellite in orbit, and then to the receiving station back on earth before being propagated through the telecommunications infrastructure. The communication is confined between the caller and the recipient. An HF radio communication, by contrast, is made between the radio operator and whoever is listening on the frequency. There is no communications infrastructure per se, thus weather information or a distress communication is widely distributed amongst many operators. As such, it is a very efficient way to disseminate information and in effect builds a community of yachts whose members use the same communication tools. Many times, a vessel in distress is assisted by the crew of another yacht operating in the region who have been listening to the same frequency. 

HF radio voice communication may be informal chatter between vessels or a more formalized communication such as a radio “net” that meets on a regular and publicized schedule in order to provide support for the local or regional fleet. Without an HF radio, a yacht becomes invisible to those just over the horizon and loses access to a supportive community. Because of the nature of HF marine radio licensing, radio nets operating on marine bands generally involve only communications between vessels, though in many remote parts of the world the same frequencies are used for inter-island communication.

However, radio nets operating on amateur radio HF bands incorporate volunteer amateur radio operators afloat and ashore. With shoreside support from individual amateurs on the ground all over the world, there are important additional benefits such as direct contact with rescue coordination centers in the event of an emergency afloat; indirect access to the Internet with all the associated benefits of information on weather; technical details about radio equipment, medical help, etc.; plus free telephone patches that bridge the gap between radio and the telecommunications infrastructure. Many of these amateur radio nets operate in the 14.300 MHz including the Intercontinental Net, Maritime Mobile Service Net and the Pacific Seafarer’s Net (see the website: 

Communications via both the SailMail and Winlink services can be handled using a free software program called Airmail.

Philip DiNuovo 

Incidentally, regardless of whether there is a legally licensed amateur radio operator on board, communications are allowed on the ham bands in the event of an emergency or vessel distress. This is important as the operators on the above-mentioned nets have the information and resources to contact appropriate officials in order to alert and advise search and rescue operations.

Digital: Digital communications aboard a yacht via HF radio include email, digitized weather reports and weather faxes. Most voyaging yachts utilize a radio modem that uses PACTOR transmission protocol to send and receive digital data. A radio modem, working in conjunction with a computer, converts digital data (e.g. your typed email) into sound that is transmitted over HF radio to a receiving modem that is also hooked to a computer. The receiving modem and computer work together to interpret the sound and generate a new digital copy of your typed email from the sound received over the radio. This digital copy will be transmitted over the Internet to your addressee. The same is done for graphics in the case of weather faxes, which are simply faxes sent via radio rather than telephone and interpreted in software to reproduce the picture on the recipient’s computer.

On marine radio bands the primary service provider is Sailmail, while on amateur radio bands it is Winlink. Communications via both services can be managed using the same free software called Airmail. As a side note, Sailmail and Winlink email can be downloaded via satellite telephone with data service or even a wireless connection to the Internet, so there is no interruption in the flow of communication if you step ashore or away from your radio.

Sailmail, a nonprofit association, currently maintains 19 stations across the world and is accessed by annual subscription. There is a usage limitation in minutes of connect time to ensure access by all members. Because Sailmail stations operate on marine bands, a ship’s station license is required to become a Sailmail member and exercise Sailmail benefits. A ship’s Sailmail address would simply be the ship’s station license call sign, thus a Sailmail address might be something like

Winlink is a network of amateur radio operators who work together with a development team; all are volunteers. At last count there were 89 Winlink stations around the world. Each Winlink station allocates a period of connect time, there is no system-defined usage limit, and in effect the amount of usable connect time is generally greater than for Sailmail. Also, because Winlink operates on non-commercial amateur radio bands, using Winlink is cost-free. In order to use Winlink aboard, however, at least one member of a yacht’s crew must be licensed on amateur band, i.e., hold an amateur radio license of a General class (or higher). We happen to use Leslie’s call sign, so our Winlink address is WZ7LL@

There are also methods for processing email and weather faxes using only the sound card of the computer and an HF radio.  For example, JVComm software facilitates weather faxes while Winmor is used for email. These methods are slower than using PACTOR (II, III or IV) but are said to be enhanced by using external sound card hardware that costs less than a modem.  

Complementary usage
Why do people, like us, use Winlink when we already have access to email and weather files using Sailmail? Or maybe the better question is why would we pay to use Sailmail when we can access free digital data by using Winlink’s 89 stations?  We argue that, used together, Winlink and Sailmail are complementary.

1. With 89 Winlink stations, each allocating connect time, the probability of exhausting connect time is low. Thus Winlink is an excellent resource for obtaining weather data, such as GRIB files, which tend to be larger files.

2. Winlink allows you to send and receive attachments with a user-defined size limit. This can be especially valuable if at sea and with an issue that requires sending a photo to a technical support specialist or a medical professional. Sailmail deletes all attachments, though GRIB files supplied by Saildocs are sent to Sailmail members as attached files.

3. You cannot send any emails via Winlink containing content that would benefit you financially. Thus when at sea and corresponding with your stock broker, for instance, you cannot legally use Winlink, so having a Sailmail subscription is valuable for this type of communication.

4. Historically, for us, Sailmail has been more reliable. Winlink stations and control software are all run by volunteers; every once in awhile Winlink has a burp, while Sailmail rarely does. So when we have a critical need to have a communication via our HF radio, we use Sailmail.

Vessel position reports are available to Winlink users.

Philip DiNuovo

5. The Sailmail teams have been and continue to be pioneers, they are fastidious in setting up their stations and Sailmail is worth supporting at the current cost of $250/yr. We send and receive thousands of emails per year via Sailmail so the cost per communication is very low.

6. Sailmail supports Saildocs, which is the source for most of our marine weather while at sea — particularly wind and current GRIB files. It will also support forwarding of text from Internet sites, which is extremely valuable when critical information is not available by email. Saildocs is available — and used — by individuals who are not Sailmail members, but without Sailmail members it would not exist. Winlink also has a catalog of available resources maintained independently of the Saildocs catalog so again, taken together, the combination maximizes resources.

7. Sailmail has a relay function, where you can send an email to a whole long list of recipients but each person gets an individually addressed email. This protects our friends and family from spammers. We write one email update of our adventures and 330 individuals receive it without seeing the other 329 email addresses.

8. Sailmail has “Shadowmail,” which you can use to monitor and manage mail for a land-based account (such as Yahoo Premium, Gmail or Hotmail) via POP protocol. Using Shadowmail, we are able to see the subject line and sender name of every email that comes into our land-based address in a special folder in Airmail. We can also forward, delete, reply to, move or archive mail remotely. Thus if we’re on a 25-day passage, we can forward important land-based email to Sailmail so we don’t miss any time-sensitive correspondence. We can also monitor and delete junk and spam, so that when we get to port, we don’t have dozens of unimportant emails clogging up our inbox.

9. Sailmail allows you to manually change your “from” address, allowing you to protect your Sailmail address when corresponding with an individual or company who you would prefer not to have your bandwidth-limited Sailmail address. Thus, you can compose and send an email via Sailmail, but it will look as if it comes from your land-based email account.

The day may come when, even if we are far out at sea, we will be able to instantly and inexpensively contact others by voice or email using simple affordable equipment not yet dreamed of. Alas, that day has not yet arrived. Right now, a yacht crew can maximize the utility of its HF radio aboard by using the complementary services offered by marine and amateur or “ham” frequencies. Since hardware and software tools are shared and licensing simple, there is really no good reason not to.

Leslie Linkkila & Philip DiNuovo have lived aboard their Mason 33, Carina, for more than six years. They are currently in the South Pacific. You can read more at:

By Ocean Navigator