Maritime tracking

The maritime layers display real-time vessel positions from the global AIS (Automatic Identification System) radio network, supplemented by OSINT-estimated positions for US Navy carrier strike groups.

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AIS vessel stream

The backend connects to the aisstream.io WebSocket at wss://stream.aisstream.io/v0/stream and maintains a live in-memory dictionary of vessel positions. The stream processes PositionReport, StandardClassBPositionReport, and ShipStaticData message types. The connection runs in a dedicated background thread (ais-stream) and uses exponential backoff (1s → 60s max) to recover from disconnections. The vessel dictionary is persisted to ais_cache.json every 60 seconds and reloaded on restart — vessels up to one hour old are accepted from cache to avoid a cold start.

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Scale

• 25,000+ vessels tracked simultaneously
• Vessels are pruned from memory after 15 minutes without a position update
• Coordinates are rounded to 5 decimal places (~1 meter precision) to reduce JSON payload size
• Flag state is derived from the vessel’s MMSI Maritime Identification Digit (MID) — the first three digits of a 9-digit MMSI encode the registering country

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Vessel classification

Each vessel is classified by its AIS type code according to the NOAA VesselTypeCodes2018 standard: “Other” type vessels (fishing boats, tugs, pilot vessels, SAR craft) are excluded from the default rendered set to reduce rendering load. They can be shown via the Civilian Vessels layer toggle.

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Sub-layers

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Carriers / Mil / Cargo

The primary maritime layer. Shows US Navy carriers (OSINT-estimated), military vessels, cargo ships, and tankers.

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Cruise / Passenger

Dedicated layer for cruise liners and passenger ferries (AIS type codes 60–69). Rendered separately to allow analysts to isolate passenger ship movements.

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Civilian vessels

Off by default. Shows yachts, fishing vessels, and recreational craft. Enabling this layer adds significant marker density, particularly in coastal areas.

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Tracked yachts

A curated list of superyachts cross-referenced against the Yacht-Alert database to surface ownership information for vessels associated with billionaires, oligarchs, and other high-profile individuals. Enabled by default.

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Carrier Strike Group tracker

The Carrier Strike Group (CSG) tracker maintains OSINT-estimated positions for all 11 active US Navy aircraft carriers. It does not use AIS data — carrier positions are estimated from open-source reporting.

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How positions are determined

The tracker operates in two phases on startup and again at 00:00 and 12:00 UTC each day:

1. Phase 1 (instant): Loads static fallback positions sourced from the USNI News Fleet & Marine Tracker and any previously cached GDELT-derived positions from carrier_cache.json.
2. Phase 2 (enrichment): Queries the GDELT News API for recent carrier movement headlines using 13 search terms (e.g., aircraft+carrier+deployed, USS+Ford+carrier). Article titles are matched against the carrier registry and against 50+ geographic region-to-coordinate mappings (seas, straits, ports, and fleet areas) to extract current operating area.

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Tracked carriers

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Position deconfliction

When multiple carriers share the same estimated coordinates (e.g., multiple ships in port at Norfolk), the tracker applies a deconfliction algorithm:

• At port: Each carrier is offset to its distinct homeport pier coordinate so markers do not stack.
• At sea: Carriers in the same operating area are spread ~0.08° (~9 km) apart perpendicular to their axis so they are visibly separate but clearly operating together.

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Clustered display

At low zoom levels, ships are clustered with a count label to keep the map readable. Clusters automatically decluster as you zoom in. Green cluster badges show the number of vessels in each cluster.

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Local AIS receiver

You can supplement the global aisstream.io feed with your own RTL-SDR dongle running AIS-catcher, which decodes VHF radio signals on 161.975 MHz and 162.025 MHz. Ships detected by your local antenna appear alongside the global stream in real time. See the local AIS receiver guide for setup instructions.