by Manal Barakat, SeaNewsEditor
A new analytical report from Sea-Intelligence examined vessel bunching as a contributing factor to port congestion across Asia.
While the majority of focus in the shipping market is on vessel punctuality and arrival schedules, Sea-Intelligence looked into the clustering of vessel departures at origin ports.
What is vessel bunching?
Vessel bunching occurs when multiple ships from the same weekly service depart within the same calendar week, rather than being evenly spaced across consecutive weeks.
This can happen due to delayed sailings overlapping with scheduled ones, the introduction of new vessels, or dual sailings involving smaller ships.
Regardless of the cause, the effect is the same: a surge in port activity concentrated into a narrow time window, placing strain on terminal resources and logistics coordination.
The Sea-Intelligence report sets a definition for analysis clarity: if two vessels sail in one week, one is counted as a bunched departure; if three sail, two are counted.
Trade lane trends
The Asia–North America West Coast trade lane has experienced a significant increase in vessel congestion since the pandemic.
After the pandemic, the situation briefly normalised, but later increased in 2024–2025.
For this trade lane, Sea-Intelligence writes, "the pre-pandemic normality was mainly in the range of 5-15% of the capacity whereas, 2024-25 is in the range of 20-25%."
A similar pattern is observed on the Asia–North America East Coast route, albeit with a temporary dip in spring 2025 that has since reversed.
The analysis extends to Asia–North Europe and Asia–Mediterranean trades, where vessel bunching has surged to levels comparable with those seen during the pandemic. The report notes that the Red Sea crisis was a contributing factor to this phenomenon.
"The common denominator for these four subtrades is that the vessels all originate in Asia, and hence from the same ports," says the data intelligence firm.
Vessel bunching straining port infrastructure
The report concludes that vessel bunching is a "seemingly unexpected" source of congestion risk at Asian ports.
These ports, typically known for their scale and efficiency, are now facing bottlenecks that defy normal statuses.
The uneven distribution of vessel departures causes sudden spikes in workload at the port. This complicates berth scheduling, cargo handling, and logistics for the hinterland.
Sea-Intelligence believes that vessel bunching is an "invisible and overlooked source of increased port congestion risk" that is likely to keep the risk of port congestion elevated.
