#### Detentions tell you more in aggregate than one at a time
Every detention notice reads as a single event: one vessel, one port, one list of deficiencies. Owners and technical managers naturally treat each one as an isolated problem to close out. But the moment you gather a large enough sample and group the underlying deficiencies by the technical area they belong to, the noise resolves into structure. Some systems detain ships far more often than others, and that distribution is remarkably stable across regions and flags.
We now track 593 detentions across the major Port State Control regimes. Of these, 365 are what we call repair-relevant — the detention was driven by a technical or structural condition that a yard, a service team, or an equipment supplier can actually address. A further 21 were non-technical (documentary, ISM, labour or certificate matters) and 207 remain unclassified pending fuller deficiency data. This piece is only about the 365 repair-relevant cases, and only in aggregate.
#### Where detentions actually come from
Sorted by technical area, the repair-relevant detentions break down like this (a single detention can involve more than one area, so the shares overlap):
- Fire safety — 75%. By a wide margin the most common technical trigger. Fire dampers, detection loops, pumps, and structural fire protection dominate.
- Hull & structure — 48%. Corrosion, wastage, and structural deficiencies remain a near-universal secondary factor.
- Pollution prevention — 40%. MARPOL-related equipment and oily-water systems.
- Life-saving appliances — 40%. Lifeboats, davits, release gear, and associated maintenance.
- Electrical systems — 40%. Emergency power, distribution, and protection.
- Navigation — 35%.
- Machinery — 25%.
- Radio & communications — 15%.
- Cargo systems — 11%.
The headline is that fire safety is not one problem among many — it is the recurring problem, present in three of every four repair-relevant detentions. Hull condition, pollution equipment, life-saving appliances and electrical systems form a dense second tier, each implicated in roughly two of every five cases. If a technical budget is being prioritized against detention risk, this ordering is where the argument starts.
#### What this means before the inspector boards
For a shipowner or technical manager, the practical value of this distribution is pre-inspection focus. A vessel calling at a high-scrutiny port does not have unlimited crew hours to self-verify before arrival. Knowing that fire safety, hull condition, and life-saving appliances account for the overwhelming majority of repair-relevant holds tells the crew and superintendent where to spend the last 48 hours of preparation — and where a quiet pre-arrival deficiency is most likely to become a detention rather than an observation.
For yards and service providers, the same distribution is a demand signal. The systems that detain ships most often are the systems most likely to generate unplanned repair scope, off-hire pressure, and urgent sourcing. Aligning capacity, spares, and technician skills with the fire–hull–LSA–electrical cluster is simply following where the recurring work is.
#### The limits of the aggregate
A distribution is a map, not a diagnosis. It tells you which systems are statistically most exposed; it does not tell you the condition of your ship. A well-maintained vessel with strong fire-safety routines carries far less of that 75% risk than the average implies, and a poorly maintained one carries more. The aggregate is most useful as a prioritization lens — a way to sequence attention — not as a substitute for the vessel-specific survey and the crew's own knowledge of their equipment.
It is also worth being honest about what the sample can and cannot say. Deficiency coding varies between PSC regimes, some records are still incomplete (hence the 207 unclassified cases we deliberately exclude), and detention is a lagging signal — it records what inspectors caught, not everything that was wrong. We treat these figures as a strong directional indicator, not a precise forecast.
#### Where this fits
We publish this aggregate view openly because inspection-readiness thinking benefits the whole sector. For teams that want to go from the pattern to their own exposure — detentions filtered by region, flag, vessel type, and specific technical area — the same dataset drives the detailed analytics inside the platform. But the starting point is the pattern above: detentions, read in aggregate and sorted by where the work is, are more useful than any single notice on its own.