Communications at Sea

We live in a connected world and yet, on a boat, connectivity remains a real challenge. Since I work full time while cruising often unpopulated parts of the world, connectivity is particularly challenging. Our approach is a hierarchy of options. Depending upon what is available, the top of the hierarchy is the highest bandwidth and, generally, the cheapest. The bottom of the hierarchy is the lowest bandwidth and most expensive.


Our first option is always WiFi. WiFi is generally the cheapest option available and is usually the highest bandwidth. Much of the South Pacific never got “last mile” wiring and so WiFi ends up becoming ubiquitous there. That’s what everyone uses and, as a consequence, it’s often widely available and at surprising distances from the base station. Often much further than in the U.S. I suspect some countries allow or don’t prevent transmission powers above those in the U.S. — or perhaps the antennas are just very well placed.

For WiFi, we run a WiFi antenna 30 feet above water at the top of our stack and use a good quality external transceiver. Signal boosters like Bullit are available, and we plan to try one but haven’t yet.


The next option is cellular. When traveling the world we each have unlocked GSM phones, so if we are going to be in an area for a while, we’ll buy a SIM card and usually open a prepaid account. When prepaid is not the cheapest option, we might do a longer-term contract depending upon how long we will be in country.

Like WiFi, cellular will work over much longer distances in some parts of the world than in the U.S. In the U.S., the cells are often configured smaller and closer together to support a large number of subscribers. When the cells are smaller and closer together, they need to operate at lower power and, as a consequence, they don’t transmit far offshore.

Cell service in places like Fiji ends up working much further from shore and, ironically, is much less expensive than in the U.S. But whether the service is inexpensive or not, it’s always much cheaper than satellite, so we always use cellular when we can.

For cellular, we run two options:

  1. A dongle directly plugged into the router
  2. A phone running a local hotspot that we connect to by the boat’s WiFi systems, which makes it available throughout the boat

  We typically just use a phone since that allows us to use a single SIM for both mobile connectivity and at the boat.

High-frequency Radio

An option that will work for many is to install a high-frequency radio and use a service like SailMail over a Pactor modem. This is far cheaper than any satellite service, but good high-frequency radio installs require some skill and there are other drawbacks. A high frequency radio is around $3,000. Some services don’t allow commercial use. And none can move large amounts of data.

Since I am working, it is commercial that I use and I need to move 100s of emails each day — some with ridiculously large attachments. Consequently, high-frequency radio is not an option that can work so we skip that option and go straight from cellular to satellite when cell becomes unavailable.


The next option is satellite and at this point things get expensive. The current best satellite option for moving large amounts of data is a mini-VSAT system. These are the most economical for large data volumes but the gear itself is expensive. We use a KVH V7 but a V3 is also a good option with coverage areas only slightly smaller than a V7. The V7, should you go that route, is an expensive piece of equipment at more than $30,000, so not worth doing unless your travels and data transmission requires it. We love the option but it is very expensive.

As much as we like the KVH V7 mini-VSAT system, it actually doesn’t cover the world, including the South pacific, much of the Indian Ocean, and both poles. We use it when we can because the service is excellent and the data rates are very good. But, when in an area where mini-VSAT is not available, we use Immarsat BGAN.

The good news on BGAN is the transmission system is inexpensive compared to mini-VSAT. A good BGAN system can be had for $3,000. More good news is it is actually a very high performance system.

So why not use it all the time if the gear is cheap and the performance is excellent? BGAN has two problems. The minor problem is you need to hand aim the antenna when on a mobile platform. The major obstacle is the cost of moving data is stratospheric. Actually, it’s higher than that. A gigabyte of data is $8,000 dollars. I know that looks like a misprint but it really isn’t. That’s why we like mini-VSAT.


The final option if nothing else is available due to failure or obstruction is to go with Iridium. Iridium has a relatively inexpensive satellite phone available — less than one-third the cost of BGAN. And, since Iridium is based upon Low Earth Orbiting (LEO) satellites, it is available absolutely everywhere on the planet. That’s why the U.S. military is their biggest customer.

So why not use it all the time? The Iridium option has two problems as well. The first is the high cost of moving data. But the major problem is it is very slow at 9,600 BPS.

Iridium ends up being the best primary option for many if not most cruisers not using high-frequency radio. But, for us, the speed is so slow that it doesn’t work adequately for the data volumes I need to move for work. We love it as a backup and it is wonderful to have something that works everywhere in the world.

That’s what we do on Dirona. We are currently posting this via Telstra (cellular) from Cape Leveque in Western Australia.

This article was first published in Three Sheets Northwest.