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Starlink vs VSAT for Ships: Choosing Vessel Connectivity

Starlink vs VSAT is a question that comes up as soon as a fleet operator starts choosing how vessels will stay connected to the office. Both are satellite links, but they come from different kinds of satellite constellations, and that difference shapes what an owner should expect from each on board a vessel.

Starlink relies on a large number of satellites in low earth orbit, much closer to the planet than a traditional communications satellite. Because the satellites are closer, the signal has a shorter distance to travel, and the network of satellites is meant to keep at least one nearby overhead as the vessel moves. The user terminal is a flat panel antenna that tracks whichever satellites are overhead at the time.

VSAT depends on a satellite in geostationary orbit, sitting far above a fixed point on the equator, which is what has made maritime satellite communication possible for a long, established stretch of time. Because the satellite is much further away, the signal travels a longer path each way, which is inherent to how a geostationary link works. A VSAT terminal on board is a stabilised dish that has to keep pointing at the same satellite position in the sky, however the vessel rolls, pitches or turns.

Coverage for a low earth orbit constellation depends on how many satellites are in range of a given position, which can vary by region as the constellation continues to expand. Coverage for a geostationary satellite depends on the satellite's fixed footprint, which weakens toward the poles and at the edges of its view of the earth. On installation, a flat panel antenna is generally simpler to mount and has fewer moving parts than a stabilised dish, while a dish antenna is a mature, well-understood piece of equipment on vessels that have carried one for years. Neither is universally better; the right choice depends on the routes a vessel actually sails and what is already fitted on board.

Why a monitoring system should tolerate either

A vessel is not always on the same kind of link for its whole voyage, so a monitoring system built around only one connection type leaves gaps whenever a vessel is on the other one, or on neither. The more useful approach is for the onboard gateway to keep collecting readings from the sensors regardless of which link is present, buffer them locally when there is no connection at all, and send everything ashore once a link, of whatever kind, becomes available again.

Connectivity in MANTRAZ

MANTRAZ treats Starlink, VSAT and cellular near the coast as different ways the same vessel data can reach the dashboard, rather than requiring one specific link. When a vessel has no connection, the onboard gateway keeps its readings and sends them once a link is back, so a change in connectivity affects when data arrives, not whether it is collected.

To see how connectivity works for a fleet that mixes Starlink, VSAT and cellular vessels, request a MANTRAZ demo.

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