Equipment choice and installation for Accessing SailMail’s Radio Network

Three components are needed to use SailMail’s worldwide network of SSB-Pactor radio stations: a marine SSB transceiver (with tuner, antenna, and grounding system), a Pactor-modem, and a computer with the appropriate software. The Pactor-modem is the only specialized piece of equipment, and is essentially a specialized modem designed for radio communications. The Pactor-modem generates the audio signals that are sent via the radio transmitter, and decodes the incoming audio signals from the radio receiver. The primary connections between the Pactor-modem and the radio are audio in/out signals, a PTT (push-to-talk) signal to tell the radio when to transmit, and a remote control wire to allow your PC to tune the radio via the modem.



Transmitting and receiving digital signals is similar to voice, and most modern marine SSB radios will do the job.

The second issue is the transmitter’s ability to transmit a continuous full-power signal without damage.  Some recent transceivers can do this without a problem (e.g. Icom M710, M700-Pro, M802), but many older transmitters will have to be operated at a reduced power setting.  If you are buying a SSB and intend to use SailMail, choose a radio that can transmit data at full power like the Icom M802.


The Pactor-modem:

SailMail works best with the SCS Pactor-IIIusb or P4dragon modems.

SailMail also works with the older SCS PTC-II, IIe, IIex,  IIpro, or IIusb modems, but if you buy an older modem make sure that it is licensed to use the Pactor-III mode, and make sure that your computer can can set your SSB frequency, which requires special cables for the modem, or an extra USB adapter for the IIex modem.    We strongly encourage all members to use Pactor-III mode.  We support Pactor-4 at all stations but expect that Pactor III mode will continue to be used by most SailMail members because of the significantly lower cost of the modem. But for those with greater communications needs, Pactor-4 offers a good way to increase capacity.


The Computer:

Any computer that can run WindowsXP/Vista/Windows7/Windows8/Windows10 will do the job.  Members with Apple computers have successfully used SailMail and the AirMail software by using Parallels, Bootcamp, or Virtual PC, depending on their preference and age of their Mac.  See the application note on Mac computers.  Most recent Windows computers and Apple computers do not have a 9-pin serial ports, and so will require a USB-Serial converter.


Other Requirements:

Besides a HF modem, radio, and computer, your on-board station will require a reliable source of 12-volt power and a good antenna. A marine SSB transmitter draws around 20 amps when transmitting at full power, and sending email requires a lot of full-power transmitting.  A full page of text is about 2000 characters which takes less than a minute using Pactor-III on a good day and somewhat less using a P4dragon  in good conditions.  Not a big number in terms of amp-hours, but if your batteries or wiring aren’t up to the task then you will have problems that may be very hard to identify.  Additionally, be sure that your batteries are fully charged PRIOR to using the SailMail system; marine SSB’s are very intolerant of low voltages, particularly when sending data.


Antenna and ground:

Antenna installation is another important topic and a good ground system is absolutely critical.   The most important aspect of a radio installation is the ground connection to the antenna tuner; this is the worst place to cut corners. The standard antenna arrangement for a sloop is to use an insulated backstay driven by an automatic tuner.  The antenna tuner is typically mounted under the deck near the backstay, and is grounded to the keel with a 3″ copper strap.  Additional 3 inch wide copper straps should also connect to nearby metal, such as stern pulpit, metal tanks, and the engine. Keep electrolysis in mind, and remember that radio ground tapes from antenna tuners can incorporate series capacitors that will block any DC electrolytic or galvanic currents.  See the West Marine Advisor article on grounds.  There is a copy of that article attached as an application note to this website.

Common mistakes are using a ground wire instead of a strap,  a ground system that doesn’t connect to enough metal, or an antenna lead wire that is run right alongside a backstay below the backstay insulator. The latter problem is very common and shunts a large part of your signal to the ocean, so put the lower antenna insulator at the extreme lower end of the backstay right above your turnbuckle or backstay adjustor.  Then use plastic tubing to insulate the lower part of the backstay (above the insulator) that is within the crew’s reach.  Radio waves propagate just fine through the plastic tubing, but the plastic tubing will protect your crew just as well as the insulation on the feed wire would have.  The fact that you don’t have the feed wire running near a grounded backstay will dramatically improve your radio’s efficiency.

Some folks ask if there is any magic length for a backstay antenna.  The answer is “yes and no.”  In general longer is better, and unnecessary wire or rod terminations are bad, so often the best approach is to have the top insulator right at the masthead, and the bottom insulator right at the top of the turnbuckle or hydraulic backstay adjuster.  This eliminates four wire terminations (which are potential failure points for your rig) and gives you the longest antenna.  There is a wrinkle (as always).  Base loaded vertical antennas are hard to efficiently load if their length is an even multiple of 1/4 wavelength (e.g. 1/2 wave, or 1 wave, or 3/2 wave …).  Therefore if you are also a ham, and 14.313 MHz is really important to you, avoid those lengths.  A 1/4 wavelength in feet is 234/(freq in MHz), so a 1/4 wavelength at 14.313 MHz is 16.35 ft.  Therefore, if you are a ham, avoid having a backstay antenna that is 32.7 feet or 65.4 feet long.  If you are not a ham and just use SailMail, then just go with the “longer is better”, and “fewer swedge fittings are better” principles and put your insulators at the top and bottom of your backstay and avoid four terminations.  There are enough SailMail frequencies so that if your tuner has trouble tuning your backstay at some frequency because you happened to end up at exactly 1/2 wavelength, there will be other SailMail frequencies on which it will work fine.  Remember when working out the length of your backstay antenna, you start measuring right at the tuner, and you include the length of the feed wire that connects to the backstay in your measurement.

Having read all of the above paragraph, remember that the most important part of your antenna installation is the ground connection to the tuner.  That is the best place to invest your energy to have a SSB that works great.

If you don’t have a backstay, then a 20+ foot marine whip antenna will work fine, again with an automatic tuner and a great ground on the antenna tuner.

The GAM antenna and KISS-SSB counterpoise are very convenient and do work, but using either or both of them will increase the amount of RF radiation inside your boat.  The GAM antenna couples RF energy to your entire rig, not just the backstay.  The KISS-SSB counterpoise radiates RF inside your boat.  If you use either of these then plan on the increased need for ferrites to keep the RF out of your laptop, modem, and other sensitive electronics such as your autopilot and wind instruments.