What to check on an Inmarsat Fleet Broadband.
2 models from SAILOR / Thrane & Thrane in Inmarsat Fleet Broadband. Below: the full model list.
What Fleet Broadband Adds Beyond the GMDSS Terminal
Fleet Broadband is a high-bandwidth satellite data and voice service running over the Inmarsat network, sold in classes offering data rates from roughly 150 kbps up to several hundred kbps depending on the terminal. It is not itself a GMDSS distress and safety terminal; that function on Inmarsat-equipped ships is carried by Inmarsat-C or, on newer installations, by Fleet Safety terminals meeting the GMDSS carriage requirement. Fleet Broadband sits alongside the GMDSS suite to carry everything the statutory distress alerting system was never designed for: crew welfare calls, email, weather routing downloads, remote diagnostics from engine and cargo system suppliers, and fleet management traffic back to the office.
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Main Components
Above-deck unit
A stabilised parabolic or flat-panel antenna tracking the Inmarsat geostationary satellite, mounted with clear sky view fore and aft and to both sides to avoid mast and funnel shadowing.
Below-deck unit
The transceiver and modem, providing Ethernet and telephone handset ports, and handling call and session setup with the satellite network.
Distribution network
Onboard Wi-Fi or wired LAN distributing bandwidth to crew welfare terminals, bridge and engine control room data links, and office systems, usually managed through a bandwidth allocation device so no single user or application saturates the link.
SIM and airtime subscription
A service agreement with an Inmarsat airtime provider, defining data allowance, streaming class priority and standby fallback arrangements.
Selection Criteria
The deciding figures are guaranteed data rate class needed for the applications actually run, since bridge weather routing and remote diagnostics need less than a full crew welfare video service, antenna size against available mounting position and mast shadowing, and whether the vessel needs streaming capacity, meaning dedicated and guaranteed-rate bandwidth for real-time applications such as video conferencing or remote engine monitoring, as opposed to standard IP capacity that is shared and best-effort.
Regulations and Interaction With GMDSS
Because Fleet Broadband does not meet the GMDSS carriage requirement on its own, ships still need an approved GMDSS terminal fitted and tested independently of the Fleet Broadband installation. SOLAS Ch. IV sets the GMDSS carriage and testing requirements for the vessel's actual distress and safety equipment; Fleet Broadband capacity is not counted against that requirement even where it is technically capable of carrying voice calls. Class and flag state surveys of GMDSS equipment do not extend to the Fleet Broadband terminal, though many owners keep it under the same maintenance contract for convenience.
Typical Faults
- Antenna tracking loss from mast or funnel shadowing on certain headings drops the link intermittently in a pattern easy to mistake for a hardware fault.
- Below-deck unit software or firmware drift causes session drops that a reboot fixes temporarily but that recur until the unit is properly updated.
- Bandwidth saturation from unmanaged crew Wi-Fi use starves bridge and engine data applications of the bandwidth they were provisioned for.
- Radome or antenna dome degradation from UV and salt exposure reduces signal margin gradually rather than causing an obvious failure.
What to Look for in a Supplier
- Airtime plan that matches actual data use rather than a generic package, since streaming-class capacity is priced very differently from standard IP.
- Antenna mounting survey to confirm sky view from the intended position before installation, not after.
- Bandwidth management hardware included or specified separately, since without it crew and operational traffic will compete unmanaged.
Never let Fleet Broadband's voice capability be mistaken by the crew for a distress communication path: the GMDSS terminal remains the vessel's only tested and required route for a distress alert, whatever else the satellite dome on the mast can do.