Fleet Utilization History

Method & caveats

• Source. Every series is one segment’s daily rows from the daily AIS-utilization snapshot (one row per snapshot date and segment). The history accumulates forward from the day it started; it is not back-filled, so early windows may be short.
• Utilization (robust). 100 × employed_tonnage ÷ total_tonnage, where employed = total minus idle. Idle (anchored, moored or stopped offshore) is read straight from AIS speed and navigational status, so utilization is the idle-complement on a deadweight basis and is independent of the registered-draught problem. A rising line = idle capacity absorbed = effective supply withdrawn.
• Adjusted utilization (experimental). Utilization multiplied by the slow-steaming speed index, to credit only fully-laden steaming rather than every not-idle ship. It deliberately reads lower than the headline and the direction is what matters; treat the level as indicative only.
• AIS coverage. The share of the segment’s registered fleet, counted by vessel, not weighted by deadweight, that had a fresh AIS fix; a quality gauge for how representative each day’s read is, shown separately because it tracks feed health, not the market. A segment with neither a fresh AIS day nor a recent fallback snapshot is left blank rather than fabricated.
• Live vs fallback days. Most days are computed live from AIS (ais_idle_dwt). On a day with no fresh AIS the platform substitutes a same-basis fallback from the latest supply snapshot applied to registry deadweight (snapshot_idle_dwt), with coverage left blank; the utilization line breaks over those gaps rather than bridging a basis switch as if it were a market move.
• Sample size / confidence. Days drawn from a thin AIS subsample (fewer than 30 observed vessels) are flagged low-confidence and are indicative only; gas carriers are always treated as low-confidence because their coverage is structurally thin. Read the trend on those segments, not a single day.
• Segments are split into gas, tanker, container, bulker and other. This is the trend companion to the latest-snapshot Supply & Demand utilization read, and a sibling of the Fleet Deployment History.