Ocean Navigator: Newsletter #5


Inmarsat C - Clearing the Confusion


I recently gave a talk on communications at a Safety at Sea seminar and was surprised at what I found when I polled the audience. Of 500 or so people in attendance, a bunch (that's a scientific term meaning somewhere around a dozen or more) of people had an Iridium or Globalstar phone, and a bunch of people had an Inmarsat Mini-M system, but almost no one had an Inmarsat C system. For a group of bluewater sailors I found this quite surprising.

In a similar story, I found myself the object of someone's ire when I suggested that Inmarsat C would be a nice complement to a recently purchased Iridium phone. The gist of the response was, "How dare you suggest I buy an Inmarsat system when I've just spent money on an Iridium system?"

Given these stories as background, I'm guessing that Inmarsat C is probably one of the most misunderstood devices on the communications market. I'll try and shed some light on what it is and what it's not.

The problem largely stems from Inmarsat's lousy job of product marketing. Any other company would likely fire any marketer who suggested product names like, "A", "B", "C", and so forth. But somehow we're stuck with sorting through Inmarsat's alphabet soup of products. Luckily Inmarsat A and Inmarsat B really only apply to larger megayachts & commercial ships so we don't have to worry about them. Mini-M is probably the most well known of Inmarsat's products in the offshore sailing market. Mini-M allows you to make voice calls, retrieve emails, and even send faxes all through a basketball sized dome. Nera, Thrane & Thrane, and KVH all make Mini-M systems.

Inmarsat C is a different beast entirely. It won't allow you to make phone calls; it won't allow you to receive faxes, though it does include text-only email capability. More importantly, it's a safety & distress system. In it's simplest form, an Inmarsat C terminal is a half-football sized antenna, and a car-radio sized transceiver hooked up to the boat's computer. Emails can be composed and received using dedicated software on the computer.

As the owner of an Inmarsat C terminal, you'll receive text weather forecasts several times each day along with navigational safety information (similar to NAVTEX). These weather and safety message all come in free of charge - care of our government and your tax dollars.

There are two buttons on the front of the transceiver that when held down for a few seconds will send out an automated distress message. The message will include your vessel's identification number, your vessel's position (through a built in GPS receiver), and your last known course and speed. The message gets automatically routed to the nearest rescue coordination center (say the US or Canadian Coast Guard for western Atlantic/eastern Pacific waters). They then take appropriate action.

Inmarsat C (commonly known as simply Sat-C) doesn't take the place of an EPIRB as it can't come in your liferaft with you, and won't float free in the event of a vessel sinking. However, it augments your safety & distress alerting system as it can provide you with 2-way communication with the Coast Guard. This can be incredibly helpful in getting them information about your situation (fire on board? medical emergency? pumps needed?). It also provides you and your crew the reassurance that someone has received your distress call and are on the way -- proven to be a substantial benefit to the morale of a crew in distress, and one that has demonstrably increased people's will to survive.

At $3,200 or so it's probably not within everybody's budget, but if you do any extended offshore cruising I think it's well worth the investment. Coverage is worldwide (except for polar regions beyond 70 degrees latitude), and the system is mandated for certain large ships under the GMDSS rules by International agreement. It's not the latest and greatest from a technology standpoint, but it is rock solid and it's not likely to be shut off or substantially changed anytime in the near future.

If you know of anyone who has the system, ask them what they think about it. I've yet to meet someone who's been disappointed with it.

Safe sailing,
Dan Piltch
dpiltch@marinecomputer.com


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