Weathernews Inc., a global weather intelligence company, has launched Offline mode for SeaNavigator for Master, its AI-powered navigation and optimization support service for ship masters, in response to onboard trial feedback that identified unreliable connectivity hindering the use of live weather data at sea.

Onboard connectivity has improved significantly in recent years, but it is not yet consistent across all regions. In trial feedback gathered between February and April 2026, masters described weak VSAT coverage in parts of the Southern Hemisphere, latency of more than 1,000 milliseconds, route imports failing on poor connections, and restrictions on satellite services in some coastal waters. One crew reported switching to a personal crew connection when the ship’s own link slowed.

Weather decision support is only useful if it is available when the decision is being made. If the connection drops during a weather-sensitive passage, the master can lose the live picture at exactly the point it matters most, posing a navigational risk and potentially affecting voyage profitability. Offline mode is designed so that a loss of connectivity no longer means a loss of situational awareness on the bridge.

Masters use a companion tool, Data Mirror Manager, to select the sea area, weather layers and forecast period they need, from seven days up to approximately 14 days. Available layers include wave height, swell, storm data, weather charts, typhoon tracks, wind and currents. A size estimate shows the download volume before it begins, so crews can match it to available bandwidth. Downloads can also be scheduled up to four times a day to follow Weathernews’ forecast updates.

When the connection is lost, the map switches automatically to the stored data. Masters can continue to review the Active Passage Plan and comparison routes alongside the stored forecast. The time of each data update is shown on screen, so the bridge team knows exactly how current the information is. When the link returns, the application reverts to live data and refreshes the forecast.

Route simulation and the AI Agent require a live connection and are not available offline. Offline mode is designed to maintain the forecast picture and planned route between connections, not to replicate the full online service.

Craig West, CEO Europe at Weathernews, said: “Our onboard trials have repeatedly highlighted the importance of connectivity, fast loading times and the need for offline capability when internet access cannot be guaranteed. It was one of the clearest messages we heard from masters.

“Too many digital tools are still designed as though the network will never go down. Offline mode starts from the opposite assumption. If the link drops in the middle of a weather decision, the master still has the forecast, the planned route and a clear view of how current that data is.”

SeaNavigator for Master was launched in December 2025 to support captains with route assessment, weather risk analysis and voyage planning. Offline mode is available now to SeaNavigator for Master users through a new desktop application, which can be installed from a shore connection or USB drive where onboard download is impractical.