Marine CMMS: What It Covers and How to Choose One
Detention rates in European ports rose again last year. Of the 16,474 inspections carried out across the Paris MoU region in 2025, 688 ships were held alongside, a detention rate of 4.18% against 4.03% a year earlier. Behind that tenth of a percentage point lies something every technical superintendent recognises: compliance is not settled on inspection day, but in the months leading up to it.
That is the ground a marine CMMS occupies. The term is used loosely, sometimes as a synonym for any maintenance software, sometimes as a sales argument. It nevertheless covers a fairly precise scope, and a family of tools that differs markedly from industrial maintenance systems. What remains is to establish what it actually covers, what regulation expects of it, and on which criteria to choose one.
The essentials
A marine CMMS schedules maintenance on machinery running hours rather than on the calendar.
It holds the records of execution the ISM Code requires, and works on board without a connection.
In 2025 the Paris MoU carried out 16,474 inspections and detained 688 ships, a detention rate of 4.18% and rising.
Fire safety accounts for 16.8% of recorded deficiencies; ISM-related findings for 4.5%.
Five criteria settle the choice: fleet size, offline operation, compliance coverage, migration of existing records, and entry cost.
What is a marine CMMS?
A marine CMMS is a computerised maintenance management system adapted to ship operation. Where a general-purpose CMMS organises the upkeep of fixed equipment on an industrial site, a marine CMMS follows mobile assets, governed by international regulation, operated by rotating crews and frequently out of network coverage for days at a time.
The term sits alongside PMS, for planned maintenance system, and the distinction is worth making. A PMS is the maintenance plan itself, the one a classification society examines, whereas the CMMS is the tool that holds it, executes it and keeps the record. In practice the two words now describe the same software.
What separates it from an industrial CMMS
The question comes up in every comparison, and fairly so: the large maintenance suites have existed for thirty years and appear to cover the same ground. Three substantive differences nevertheless separate the two families.
The scheduling unit. A plant schedules by calendar because it runs continuously. A ship schedules by counter: an engine that has run 400 hours in three weeks and then nothing for two months does not fall due when a calendar says it does. A marine CMMS triggers on hours actually run.
Compliance as a first-order function. Certificates, procedures, records of execution: what ship maintenance produces is not only availability, it is a file. An industrial CMMS treats documentation as an accessory; a marine CMMS puts it at the centre.
Offline operation. This is the point that disqualifies most tools in practice. If the crew has to wait for coverage before logging a job, they will write it on paper and re-enter it three days later, or not at all.
A commercial difference follows. The integrated suites of the maritime market, built for owners running several hundred ships, presuppose a deployment project, a budget and a dedicated team. They remain relevant at that scale, far less so for a fleet of ten. The market's recent move towards the single suite changes nothing in that arithmetic.
What the ISM Code expects of a maintenance plan
The International Safety Management Code devotes a full section to maintenance of the ship and equipment. The Company must establish procedures ensuring the ship is maintained in conformity with the applicable rules, arrange inspections at appropriate intervals, report any non-conformity with its possible cause, take corrective action, and keep records of those operations.
The Code further requires identifying equipment whose sudden operational failure may result in hazardous situations, what the trade calls critical equipment, and providing specific measures to promote its reliability, including regular testing of stand-by arrangements not in continuous use.
None of this mandates software. Yet an auditor does not assess intent: they ask to see the plan, the records of execution, the dates and the names. A well-kept binder answers that. A poorly kept one, split between ship and shore, does not, and that is the more common case. Our ISM compliance checker gives a fleet its bearings in a few minutes.
What port state control reveals
Port state inspections give the most tangible measure of the gap between declared and observed compliance. The Paris MoU annual report for 2025, published in July 2026, records a deterioration: 688 ships detained out of 16,474 inspections, a detention rate of 4.18% against 4.03% the previous year. Nineteen ships were refused access to ports in the region.
Within the findings, fire safety leads with 16.8% of records, ahead of structural and electrical elements, then health protection and seafarer welfare under the Maritime Labour Convention. ISM-related deficiencies account for 4.5% of the total. These families share a trait: they are prevented by maintenance that is carried out and recorded, not by a scramble the night before the call.
The seven functions a marine CMMS should cover
The expected scope has settled. A tool that leaves one of these domains aside forces a separate file to be kept alongside it, which recreates the very fragmentation the system was meant to remove.
Planned and corrective maintenance. Maintenance plan per item of equipment, triggering by counter or date, execution reports with attachments.
Engine log and running hours. Counters per machine, tank levels, consumption.
Deck logbook. Passages, port calls and events on board, ideally fed by AIS to avoid double entry.
Inventory and purchasing. Stock per ship, alert thresholds, spare part requests and supplier orders tied to the jobs that prompted them.
Document management. Certificates, insurance, registration papers and procedures, filed per ship and readable from on board during an inspection.
Crew management. Hours of work, rest, leave and rotations, a subject that has become central since the MLC framed those conditions.
Fleet oversight. Status of each ship, overdue jobs, open alerts and cost per unit, on a single screen.
These functions are set out in detail in the twelve BoatOn Book modules.
Five criteria for choosing
Fleet size. This is the criterion that eliminates fastest. Below fifty ships an integrated suite costs more in project work than it returns in functionality; above two or three units, the spreadsheet starts to lie.
Offline operation. To be verified in a demonstration rather than on a brochure: ask to log a job in flight mode, then to see what syncs afterwards.
Compliance coverage. The tool must produce, without manipulation, the statement an ISM auditor or a PSC inspector asks for. If the output requires an export and then formatting, it will not get done.
Migration of existing records. A fleet in service already has a maintenance plan and a history. Migrating them is the leading cause of failed deployments: have it quoted and supported before signing.
Entry cost and commitment. Between an annual licence bundled with an integration project and a monthly subscription that can be cancelled, the gap is not only financial: it is the ability to try without committing the financial year. Our return on investment calculator helps set the orders of magnitude.
One further point, less often raised: adoption by the crew. A tool seafarers do not fill in produces a false history, which is worse than no history at all, since it invites misplaced confidence.
Where BoatOn Book sits
BoatOn Book is a marine CMMS built for professional fleets of 5 to 50 ships. It brings together the seven functions described above, runs in a browser and in mobile apps, and works on board without a connection. The trial is free for thirty days and the subscription remains cancellable monthly.
The positioning is deliberately the middle ground: more structured than a spreadsheet, lighter than an integrated suite. Dedicated pages set out the case for cargo and merchant shipping, passenger vessels and boat rental fleets, and a frequently asked questions page answers the most common queries on pricing, compliance and deployment.
What neither the software nor the regulation settles on the owner's behalf is the essential part: a CMMS does not manufacture compliance, it makes visible what has been done and what has not. That is already a great deal, at a moment when detention rates are climbing and inspectors are asking for evidence rather than intentions.
Sources: Paris MoU annual report on port state control for 2025, published July 2026; International Safety Management Code (IMO), section on maintenance of the ship and equipment. Illustrative photograph.
