A Planned Maintenance System (PMS) schedules routine maintenance on shipboard equipment at defined intervals — based on running hours, calendar time, or both — rather than waiting for something to fail before addressing it.
Why Planned Beats Reactive Maintenance
Waiting for equipment to fail before fixing it (“breakdown maintenance”) is unpredictable and often more expensive and dangerous — a failure at sea, mid-voyage, in bad weather, is a fundamentally worse situation than a scheduled service in port. PMS shifts maintenance to predictable, planned windows, catching wear and developing problems before they cause an actual failure.
How PMS Actually Works
- Each piece of equipment has a defined maintenance schedule (e.g., “replace lubricating oil filter every 500 running hours”)
- The system (traditionally paper-based, now almost universally software-managed) tracks running hours or elapsed time and flags when maintenance is due
- Completed maintenance is logged, creating a documented history for each piece of equipment
- Spare parts requirements are often linked to the schedule, supporting inventory planning
PMS and the ISM Code
A functioning PMS is a required element of a vessel’s Safety Management System under the ISM Code — maintenance isn’t treated as a purely technical/engineering matter but as a documented safety management responsibility, since equipment failure is a genuine safety risk, not just an operational inconvenience.
Real Consequences of a Poorly Maintained PMS
Deferred or skipped maintenance, or a PMS that exists on paper but isn’t actually followed, is a common finding in incident investigations and Port State Control deficiencies — a PMS is only genuinely useful if it’s actually executed, not just documented as existing.
Class and PMS
Classification societies increasingly offer Condition-Based Maintenance or PMS-linked survey arrangements, where following a well-documented PMS can substitute for some traditional fixed-interval class surveys on certain equipment — a real, practical benefit of running a genuinely disciplined system.
Exam Relevance
PMS principles, its role within the ISM Code SMS, and the real operational risks of poor maintenance discipline are core Ship Knowledge and Safety Management topics in deck and engineering officer competency exams.