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Internet access for voyagers

Oct 25, 2013

An overview of the options for setting up a voyaging boat

(page 3 of 3)

Inmarsat — Geosynchronous (“geostationary”) orbits (GEO) — Inmarsat satellites orbit the Earth directly over the equator at an altitude of about 22,236 miles. The period of their orbits exactly match the rotational period of the Earth and so they appear to be stationary over one spot on the Earth at all times. This is why all the Dish Network TV dishes in your neighborhood point in precisely the same direction.

Courtesy Furuno

Another satellite option is Inmarsat’s Fleet Broadband service using a unit like this Furuno Felcom 500.

GEO satellites always have a consistent view of the Earth below, and with control of onboard antennas they can increase capacity in some areas while reducing it in others. Most voyagers would never reach the polar limits of Inmarsat’s coverage. Because GEO satellites are so far away, antennas here on Earth need to be high-gain and highly directional.

For this reason, dishes are the most common form of antenna and for use on board boats these dishes need to be actively steered to always point at the selected satellite. As a result, the antennas tend to be larger, heavier, and more power hungry than most 40-foot boats care to carry.

But, the payback is consistent Internet access — and telephone access — with relatively high speeds (128 kb/sec - 4 Mb/sec). The cost will be high — entry-level terminals cost on the order of $10,000 and per-call or per-megabyte costs can be $0.50 to $1.00.

Iridium — Low Earth orbit (LEO) — Iridium satellites orbit the Earth at an altitude of only 485 miles. As a result, lower power and omni-directional antennas can be used on board. Also as a result, any given satellite will only be in view for a short period of time from a fixed point on the Earth’s surface. This is why the Iridium spaceborne fleet consists of 66 satellites in six different planes of orbit — in this way one or more satellites should be visible everywhere on Earth at any given time. (In the original concept, there would have been seven orbital planes with 11 satellites each. The name Iridium reflects the 77-component concept — the atomic number of iridium is 77. Later it was determined that six orbital planes were sufficient. The name was never changed to Dysprosium.

The Iridium network offers true global coverage because of its ability to relay data from satellite to satellite in real time. Since a satellite 485 miles above the Pacific Ocean is not going to be able to “see” a ground station at the same time, in order to establish its connection from your boat to the Internet, it needs to relay your data to another satellite nearby that can communicate with a ground station.

Courtesy KVH Industries

KVH Industries offers a value-added service called Mini VSAT using their TracPhone V7 and V3 antennas. Coverage is extensive.

Iridium phone calls and data connections can be reliably established from anywhere on Earth, but they have a tendency to drop out after a short period. In one test by Defence Canada, 70 percent of calls were dropped with the average drop time of just over four minutes. Still, four minutes is a lot of data and, in my own experience, 10-minute calls are commonplace.

Iridium modems operate at low speed — 10-20 kb/sec — and generally cost about $1.00 per minute or thereabouts, based on available calling plans. Modems cost on the order of $1,000. You won’t be sending friends pictures of your freshly caught tuna at these rates, but downloading tomorrow’s weather would be reasonable.

Globalstar — LEO “bent pipe” satellites — Globalstar satellites are also in low Earth orbit at an altitude of about 850 miles. Unlike Iridium satellites, the Globalstar birds cannot relay messages from satellite to satellite. Therefore, in order to establish a connection from user to network, the satellite must be simultaneously in view of the user and a Globalstar ground station. For this reason, Globalstar’s coverage — while far reaching — does not include the world’s oceans, or indeed even the southern African continent. Globalstar does offer competitive rates for North and South America, and in between. Like Iridium, its modems are smaller and the antennas are omni-directional.

Value-added services — In addition to the satellite network operators, there are numerous value-added services and companies out there who have tailored solutions to the maritime service. SPOT is a form of (almost) global voice and data service. KVH Industries, on the other hand, is an end-to-end satellite communications company that offers a full range of size and performance voice and data terminals. KVH’s TracPhone V7 and V3 units have antennas small enough for larger yachts. Both units can download data at 2 Mbps and can provide telephone services. The cost for data is less than an dollar a megabyte, but can add up fast with large downloads. Telephone charges are based on the plan you purchase. In the case of the TracPhone V3, the price is almost 50 cents a minute. Using a combination of Ku- and C-band signals, these TracPhone products provide voyagers with Internet connectivity in most areas around the world.

Offshore communications are not yet a trivial commodity for small voyaging boats. There is a commitment of money and energy that must be made to bring the Internet — and its benefits and services — to a small, offshore platform.

If you are contemplating a voyage, consider these alternatives, talk with other voyagers, and do your homework before you go offshore. With today’s breadth of technologies, you will find an appropriate mix for your ambitions, your budget, and your boat.

Jeff and Raine Williams circumnavigated (and then some) in their J/40 Gryphon. They now live and cruise in New Zealand.

Edit Module

Dec 19, 2013 10:48 am
 Posted by  Yachtdaemon

Excelkent advice thanks, just a couple of comments to add:
- When looking at Winlink v Sailmail, remember Winlink cannot be used for business. Also we have had several fellow cruisers who use Winlink complain that it is getting more difficult to get access as shore stations are closing
- One very cost effective way of having Internet access in foreign ountries is to buy a local prepaid SIM card and use that as required for data on a computer, smart phone or tablet. Access in developing countries can be quite inexpensive, although coverage may be patchy.

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