What public records and authorities track yacht port logs and AIS data, and how can they be queried?
Executive summary
Public and private actors jointly record yacht movements: Automatic Identification System (AIS) broadcasts are captured by coastal (terrestrial) stations and satellites, archived by government programs and numerous commercial aggregators, and port authorities maintain arrival/departure logs that can be correlated with AIS to produce port-call histories [1] [2] [3]. Querying these records ranges from free community feeds and government downloads to paid APIs and commercial historical datasets, each with different access methods, formats, coverage and legal limits [4] [5] [3].
1. Who collects AIS data: shore stations and satellites
AIS is transmitted by vessels and routinely received by land-based AIS receivers and increasingly by satellites; land stations and mobile shore Aids‑to‑Navigation (AtoN) produce much of the coastal coverage while satellites extend global reach, and both feed the various public and commercial archives used for vessel tracking [1] [2].
2. National authorities and public archives that track AIS and port traffic
In the United States, the U.S. Coast Guard operates the Nationwide AIS (NAIS) program and a Vessel Information Verification Service for certain static AIS fields, but does not broadly publish NAIS raw feeds to the public or commercial purveyors, instead offering curated services and access channels for official use [1]; NOAA’s Marine Cadastre aggregates and documents vessel-traffic resources and provides tools and tutorials for accessing AIS data and vessel traffic products [5] [6]. Defense and research reports also archive historic AIS within U.S. waters and describe use cases for incident reconstruction and planning [7].
3. Port authorities and port-call logs
Individual port authorities and vessel traffic services maintain port-call records and manifests at different levels of openness—these records can be reconstructed or augmented by correlating AIS tracks with predefined port polygons to produce arrival, departure, anchorage and berth-time details [2] [8]. Availability and formats differ by port and country: some ports expose schedules and historical calls directly, others require formal requests or commercial services to assemble complete yacht-specific port logs [2] [3].
4. Commercial and community aggregators: where most users go
Commercial platforms such as MarineTraffic, VesselFinder, VT Explorer, VesselTracker and MyShipTracking aggregate terrestrial and satellite AIS into searchable maps, historical archives and paid APIs—these services offer near‑real‑time maps, vessel particulars and port‑call APIs but usually put advanced historical data or bulk exports behind paid tiers or credits [9] [10] [11] [12] [13]. Community projects like AISHub provide a free AIS sharing model and API access for validated contributors, useful for live feeds and simple queries in JSON, XML or CSV [4].
5. How to query AIS and port logs: formats and tools
Common access methods are web interfaces, REST APIs, bulk downloads and geospatial services: APIs return JSON/XML/CSV, commercial historical services offer endpoints to query port calls by vessel MMSI/IMO or port LOCODE, and GIS/WFS endpoints and CQL filters let users request geometrically bounded historical position sets in GeoJSON, Shapefile or CSV for polygon-based port-event analysis [3] [8] [2]. Government tools and tutorials (e.g., MarineCadastre’s AIS Data Handler) explain decoding, masking rules and filtering [6].
6. Limits, privacy and reliability caveats
AIS is designed for safety, not forensic certainty: transponders can be switched off or spoofed and some datasets mask identifiers for privacy or security reasons [1] [6]; terrestrial reception leaves coverage gaps offshore that satellite AIS fills imperfectly, and commercial aggregators apply filtering, downsampling or crediting schemes that affect completeness and cost [2] [3] [8]. Users seeking official or legally admissible port logs should verify provenance with port authorities or the Coast Guard rather than relying solely on third‑party reconstructions [1] [7].
7. Practical first steps to get data
Start with free public tools: join AISHub for a community feed and test queries in JSON/XML [4], use MarineTraffic/VesselFinder web maps for quick lookups [9] [10], consult MarineCadastre for U.S. downloads and tutorials [5] [6], and move to paid APIs (VT Explorer, VT Explorer PortCall API or VesselFinder historical services) when needing validated historical port-call datasets, bulk exports or legal-grade reconstructions [3] [2]. For port-level accuracy, cross-check AIS-derived port events against the port authority’s official call logs or the Coast Guard’s verification services where available [1] [2].