ANCHORAGE OPTIMIZATION
Beyond vessel counts How smarter anchorage analysis can unlock port fluidity By Lee Barrett-Lennard, Research Lead, Clear Seas Clear Seas’ analysis of commercial anchorages in the Canadian waters of the Salish Sea shows why reducing congestion requires ports to look beyond ship arrivals — and manage the broader supply chain conditions for whether vessels wait, where they wait, and for how long.
W hen congestion builds around a port, vessel num- bers are often the first metric to attract attention. More ships can mean more pressure on berths and anchorages; fewer ships should mean relief. Yet the record of commercial anchorage use in the Canadian waters of the Salish Sea tells a different story. Clear Seas’ analysis of Pacific Pilotage Authority vessel-movement data across 71 commercial anchorages from 2016 to 2023 found that total time at anchor rose by 90 per cent even as commercial vessel traffic fell by 14 per cent. From 2023 to 2025, the pattern reversed: traffic rose by 22 per cent, while anchorage use declined by 23 per cent. That divergence is more than an analytical anomaly. It gives ports a
absorb variability: a vessel may wait because a berth is occupied, cargo is not ready, railcars are delayed, or load- ing is constrained by weather condi- tions. Anchorages keep that variability from immediately stopping port oper- ations, but extended waiting reveals accumulating friction. This distinction matters. Ports can complement arrival counts with meas- ures such as the proportion of trips that anchor, average and median anchorage duration, time spent waiting before the first terminal call, time between ter- minal visits, seasonal demand, and the distribution of waits by terminal, vessel type and commodity. These measures show whether pressure comes from underlying growth, recurring operat- ing constraints or exceptional shocks — and therefore whether the best response is new capacity, better sched- uling, improved inland connections or contingency planning. Segment the problem by com- modity and voyage phase These results also show why aggre- gate averages can hide the operational source of congestion. Bulk carri- ers account for about 85 per cent of anchorage demand, with vessels carrying grain and coal generating 70 per cent of all time at anchor in 2025. Those figures focus attention on a relatively concentrated set of cargo flows rather than on all marine traffic equally.
practical way to rethink congestion. Anchorage demand is not simply a product of how many vessels enter a region. It is driven by vessel types, the availability of terminals and cargo, and the duration of each vessel’s stay. Those outcomes, in turn, reflect terminal efficiency, rail performance, weather, operating practices, disruptions and coordination across the supply chain. If ports monitor and manage these fac- tors, they can target the causes of wait- ing instead of treating anchorages as a passive overflow area. Anchorage time is a perform- ance signal The central insight from this analysis is that total time at anchor is a system- performance indicator. Anchorages
Figure 1: Anchorage Use in the Canadian Waters of the Salish Sea (2016-2025)
October 2026 — PACIFIC PORTS — 29
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