UPS & Power Integrity
This guide covers the power resilience requirements for in-scope computer-based systems, ensuring that security state is maintained during power transitions and that critical CBS continue operating during outages. Under IACS UR E27 §4.1, suppliers must specify and document the power supply requirements and backup duration for every CBS they deliver — the shipowner is responsible for implementing those requirements aboard the vessel.
A maritime UPS is more than a battery backup — it is a power conditioner and a security continuity device. It protects sensitive OT hardware from the voltage spikes and frequency fluctuations common during heavy weather or large motor starts (bow thrusters, cargo pumps). More importantly from a cyber perspective, it prevents the firewall, core switch, and IDS sensor from rebooting during a brief power interruption — which would create a window of zero network visibility and zero access control enforcement.
Critical UPS specifications — maritime grade requirements
Standard consumer UPS units are not sufficient for maritime OT security infrastructure. The following specifications are required for CBS covered under E27.
1 — Double-conversion (online)
The UPS must continuously convert AC to DC and back to AC. This ensures zero transfer time during a blackout — the firewall and switches never see a power interruption because the UPS output is always active, not switched in on failure.
2 — Managed SNMP monitoring
Every security UPS must have a network management card configured to send SNMP traps to the AMS and syslog server on battery health degradation, input power loss, overload, and low battery — before the next blackout, not during it.
3 — Maritime environmental rating
UPS units in the ECR must be rated for the marine environment — IEC 60945 or equivalent. This covers humidity, temperature range, vibration, and EMI tolerance. Consumer rack UPS units will fail in ECR conditions within months.
Security infrastructure load management
The ETO must verify that the security UPS is not overloaded. A UPS carrying non-security loads will have reduced runtime during a blackout — potentially insufficient to bridge the gap before the emergency generator comes online. Keep the security UPS dedicated to security and connectivity assets only.
Runtime calculation — bridging to emergency generator
The UPS must provide sufficient runtime to bridge the gap between main power loss and emergency generator pickup. SOLAS requires the emergency generator to start and assume load within 45 seconds — the UPS must sustain the security infrastructure for at least this period with a safety margin.
Battery health verification — quarterly checklist
Battery health indicators on the UPS management card are not sufficient for compliance evidence. These physical checks are required quarterly and the results must be logged.
Blackout drill verification
During a “dead ship” drill, the ETO must confirm the resilience chain. The firewall uptime log is the evidence — a system restart entry means the UPS failed to bridge the transition.
- T-0 — main power lost: UPS takes over immediately. Firewall status must remain ACTIVE with no restart. Check firewall uptime counter — it must not reset.
- T+10s — UPS on battery: SNMP trap should have arrived in the syslog indicating “on battery” status. If no trap received, the SNMP monitoring has failed — log as a finding.
- T+30–45s — emergency generator starts: UPS transfers back to AC charging. Confirm transfer was smooth — no voltage spike on the UPS output that could cause CBS instability.
- Post-drill verification: Check firewall uptime log, switch uptime, and syslog server continuity. Log actual battery runtime achieved and compare against the required 5-minute minimum. Any CBS that restarted during the drill must be investigated — either the UPS load exceeded capacity or the UPS itself has a fault.
E27 documentation requirements
UPS coverage is part of the power supply specification that E27 vendors must provide per §4.1. The shipowner must document how those requirements are implemented aboard the vessel for the CSDD.
The specific regulatory requirements this playbook satisfies. Use these references when preparing for Class survey or responding to a surveyor's checklist.
