Reference
Maritime Glossary
Plain-language definitions of the shipping and port terms used across Portflow.
Twenty-foot Equivalent Unit
The standard unit of container capacity: one 20-foot container. A 40-foot box counts as 2 TEU. Port throughput rankings are published in TEU per year.
Vessel draft
How deep a ship sits in the water, measured from waterline to keel. A port's maximum draft limits which vessels can enter fully laden.
Time alongside
The hours a vessel spends tied up at a berth, from first line to last line. Shorter dwell means faster cargo operations.
Queue time
Time a vessel spends at anchor outside the port waiting for a berth. Rising waits are the classic congestion signal.
Position report delay
The gap between a vessel's real position and its latest AIS (Automatic Identification System) report. High latency makes tracking less reliable.
Automatic Identification System
Transponders on ships that broadcast identity, position, speed and course. The backbone of vessel tracking.
Boxship
A vessel built to carry standardized containers. Measured in TEU capacity; the largest carry over 24,000 TEU.
Bulker
A ship carrying unpackaged dry cargo such as grain, coal or iron ore in large holds.
Liquid bulk vessel
A ship carrying liquids in tanks — crude oil, refined products, chemicals or liquefied gas.
Roll-on / Roll-off
A vessel where vehicles drive on and off via ramps — cars, trucks and trailers.
Hub transfer
Moving containers between ships at an intermediate hub port rather than sailing direct. Hub ports like Singapore handle huge transshipment shares.
Port volume
Total cargo handled by a port over a period — for container ports, measured in TEU lifted on and off vessels.
Utilization
The share of time berths have a vessel alongside. Very high occupancy leaves no slack and causes queues.
Vessel visit
One visit by one vessel to a port: arrival, berthing, cargo operations and departure.
Location code
A five-letter United Nations code for trade locations — e.g. USLGB for Long Beach. Used across shipping documents.
Delay measure
A composite of anchorage waits and berth delays showing how far a port is running behind its normal pace.
Yard dwell
How long a container sits in the terminal yard between discharge and pickup (or drop-off and loading).
Feeder ship
A small container ship that shuttles boxes between regional ports and major hubs.