Where it happens
Circle size grows with contact duration · click a circle for detailsBusiest service vessels
Click to focus on one vesselOver time
Encounters starting per hour (UTC) · click a bar to filter to that hourHow long they stay
Contact duration per type, minutes (log-spaced bins) · click a bar to filterTop locations
Berth of the served vessel, or underwayWho gets served
AIS ship type of the served vesselEncounter log
| Type | Checks | Service vessel | Served vessel | Start (UTC) | Duration | Where | Δ speed | Side | Replay |
|---|
How the detection works
1Positions
All AIS positions inside the V2V detection polygon, resampled to a 15 s grid by the existing pipeline. Read only, from V2VPosition.
2Hull contact
Each vessel is drawn as a rectangle from its AIS dimensions and heading. A contact starts when two hulls come within 20 m and ends beyond 50 m. At least one of the two must be a service vessel type.
3Movement
Who moved in the 15 min before and after the contact separates a vessel coming alongside from one passing by, a ship berthing next to a moored boat, or neighbours lying still.
4Type & checks
The type comes from the service vessel's AIS ship type. Plausibility checks per type (duration, speed match, who is larger, lying parallel) are reported, not used to hide anything.
Known limits of this prototype
- No ground truth yet: “plausible” means “passed the rules”, not “confirmed”.
- Several pilot and bunker boats send a generic AIS type (e.g. OTHER), so the type alone misclassifies them. A curated list of service vessels would fix most of this.
- About half of the positions carry no true heading, which blurs the hull shape.
- Only inside existing V2V polygons; pilot stations at sea are outside.