When a vessel is detected in satellite imagery, we match it to nearby vessels broadcasting their location via AIS. This is done using a probabilistic method that accounts for the positional uncertainty of both the satellite detection and AIS-reported positions. Each potential match is scored between 0 and 1, indicating the likelihood that the detection corresponds to a given AIS vessel.
Probabilistic matching was introduced to Starboard in May 2025. Please note that any detections matched prior to May 2025 do not account for proximity.
The colour classification of the detection symbols are:
⬜ AIS match: Match score greater than 0.5
🟨 Possible dark vessel: Match score 0.5 or less
🟥 Likely dark vessel: Match score is not defined
Uncertainty calculation: The estimated AIS position at the time of detection is derived by interpolating between the vessel’s known positions before and after the satellite data capture. The uncertainty around this interpolated location is shaped by how far the vessel could plausibly travel in that time. We also consider the geolocation accuracy of the satellite sensing system to compute the final match probability.
A satellite vessel detection matched to an AIS transmitting vessel is selected. Hovering the mouse over the matched vessel name in the vessel detection panel visualises the area of uncertainty of the vessel position.
A possible dark vessel detection is indicated by a yellow square. The location of the detection is just inside of the area of uncertainty of the vessel position.
Several possible matches: Our data interpolation and uncertainty logic helps to avoid false matches even in busy areas. If multiple vessels have very similar match scores, their names are displayed in the detection panel for visual inspection.