A vessel network carries three quite different kinds of traffic with three quite different requirements, over a connection that costs money by the megabyte.
Getting the separation right is a safety and regulatory matter. Getting the bandwidth management right is what makes the connection usable.
Three separate networks
Navigation and safety systems
Type-approved equipment subject to survey. This network should be isolated, and general-purpose computing has no place on it.
Where data must cross — a position feed to an operational system, for instance — it should be through a controlled, documented, one-way interface rather than a shared network. Any work on this equipment belongs with approved service providers.
Operational systems
The vessel's business computing: planned maintenance, cargo and stability systems, crew records, reporting, engine monitoring, the master's administrative work.
This is where most maritime IT effort sits. It needs to work offline, synchronise ashore when it can, and be supportable remotely.
Crew welfare
Personal devices, personal use. Isolated entirely from the other two, with its own bandwidth allocation.
Crew connectivity is now a serious recruitment and retention issue, and it deserves to be provided properly rather than grudgingly. It also deserves to be separated properly, because a hundred personal devices are a hundred devices nobody manages.
Separation aboard is not a preference expressed in network design. It is a regulatory position, and it also happens to be the arrangement that works.
Satellite options
Geostationary services have provided maritime communications for decades. Coverage is broad and predictable, and the physics impose a noticeable round-trip delay that makes interactive work feel slow regardless of the speed available.
Low earth orbit constellations have changed expectations considerably. Latency is much lower and speeds much higher where coverage exists, at costs that have made continuous connectivity viable for vessel classes that previously could not consider it.
Coverage, service terms and maritime licensing differ between providers, and both the technology and the commercial landscape are moving quickly. Verify the current position for your operating area rather than relying on a general description.
Terrestrial connections — mobile networks in coastal waters and port wi-fi — remain valuable and considerably cheaper. A vessel that automatically prefers a cheap connection when one is available, and defers large transfers until then, saves real money.
Many vessels now carry more than one service, using one as primary and another as backup, with automatic failover.
Managing the bandwidth
Without management, a vessel connection is consumed by whatever asks loudest. In practice that means automatic updates and video streaming, neither of which is operationally important.
What to put in place:
Prioritisation. Operational traffic ahead of crew use. Voice and small operational messages ahead of bulk transfers.
Update control. Block automatic operating system and application updates from downloading over the satellite link. Stage them instead — cache them aboard when in port or on a cheap connection, then deploy. This single measure often saves more than any other.
Fair crew allocation. A per-user allowance or a rate limit, so one person streaming does not consume the whole ship's connection. Crew accept a defined allocation far more readily than an unpredictable service.
Compression and deduplication where the traffic suits it.
Deferred bulk transfer. Large files queued for the next cheap connection rather than sent immediately.
Visibility. Somebody aboard and ashore should be able to see what is consuming the connection. Most surprises are explained the moment anybody looks.
Getting operational data ashore
The commercial value of vessel connectivity is mostly here: noon reports, fuel consumption, engine data, maintenance records, cargo status.
Design principles that work:
Send summaries, not raw data. Engine monitoring generates enormous volumes. Send the aggregates and the exceptions routinely, and the detail only when investigating something.
Make transfers resumable. Anything that restarts from the beginning after an interruption will not complete.
Queue and forward. Data generated during a coverage gap should queue aboard and send when the link returns, in order, without anybody intervening.
Acknowledge properly. The vessel needs to know what actually arrived, or reconciliation becomes a manual task ashore.
The general principles are the same as any integration, with the failure cases far more prominent — see how systems talk to each other.
The physical installation
Antenna siting matters more than equipment specification. Blockage by masts, funnels and cranes causes dropouts that get attributed to the service. A survey before installation is worth the cost.
Then the ordinary maritime disciplines: appropriately rated equipment, secured connections, supported cable runs, protection against power disturbance, and spares aboard for anything critical. The reasoning is in maritime IT explained.
Security
A vessel with a permanent internet connection has the exposure of any connected organisation, with less capacity to respond. Covered separately in maritime cyber security.
Our team's background spans maritime and business systems, including GMDSS-certified radio operation. Start a conversation if you are designing vessel connectivity and want the shore systems considered at the same time.
