Understanding the maritime map
Sources, photograph credits and reuse conditions
This platform brings stored maritime observations together. Every layer has its own coverage, date and limitations.
Common questions
Why can’t I see a particular boat?
Check the search, provider, vessel category, speed and observation-age filters first. Category filters require a matching stored AIS profile; boats without one will not appear in that category. A recent-only filter hides older reports.
Try the ship catalogue or My boats for a last-known report. Reception gaps, delayed reports and missing data can all affect visibility. A configured collection area alone does not guarantee reception.
Why is there a ship in the photograph but no map marker?
Land and port imagery is reference photography taken at an earlier time. A photographed ship is not a current vessel observation. Its identity and present location cannot be established from its appearance on that image.
Why is the observation still old after I refresh?
Refreshing checks what the platform currently stores. It does not make the provider send a new observation. Read the observation timestamp as well as the time the page was checked. Favourite reports retained after a failed refresh are labelled explicitly.
Does an empty port view mean the port is quiet?
No. Port counts describe reports inside an approximate reference window and time interval. The window is not a surveyed port boundary, and AIS reception can be incomplete. Open the port page for the measured reception context and source details.
Reading vessel positions
- Teal: a stored AIS report up to one hour old.
- Amber: a report older than one hour, up to 24 hours.
- Grey dashed: more than 24 hours old, or an uncertain timestamp.
These styles apply to individual AIS symbols. Numbered clusters group observations; they do not have one shared observation age. Click a vessel to read its provider and timestamp.
AIS is self-reported and reception is incomplete. A marker is a reported position, not proof of where the vessel is now. Missing markers do not establish an empty sea or harbour.
Different kinds of satellite information
- AIS reports: vessel messages received through the displayed provider.
- Satellite detections: separate dated observations, not automatically identified vessels or live AIS.
- Scene footprints: where a satellite image was acquired; a footprint itself is not a ship detection.
- Reference imagery: land and coastal photographs that may be years old. They show geographic context, not present weather or vessel positions.
Coastal imagery and weather
Selected Southampton and Portsmouth areas use locally stored 2022 CCO originals at 10 cm resolution. Watermarked CCO WMS is optional and off by default; its automatic year selection places 2024 above 2023 above 2022. Transparent survey gaps expose the underlying layers. Source checks describe sampled pixels, not complete survey coverage. Other providers retain their own attribution and dates.
Weather station readings are measured at a station and time. They are not a measurement everywhere nearby. Forecast/model layers and weather satellite images are separate products. An unavailable value means unknown, not zero or calm conditions.
Ports, depths and infrastructure
Port reception counts use small windows around reference points, not full port boundaries or confirmed arrivals. Mapped piers and terminals are references, not berth assignments. Depth grids have different resolution and vertical datums; shaded bathymetry is not a live depth measurement.
Use current official charts, notices and relevant authorities for navigation and safety decisions.
Vessel specifications
Deadweight describes carrying capacity; it does not reveal current cargo. Gross and net tonnage are volume-based indices, not vessel weight. Displacement depends on loading condition. Missing specifications stay unknown, and source claims remain separate from AIS reports.
Your saved information
Signed-in favourites and settings belong to your local account. Signed-out preferences stay in that browser. Private groups do not share information; shared fleets use a separate explicit invitation flow.