Navigation, Communications & GMDSS Power

2 February 2026 3 min read Electrical, Latest Articles

When Power Loss Turns a Casualty into Isolation

Introduction — power loss is survivable, loss of communication is not

Ships can survive without propulsion. They can drift, anchor, or be assisted. What ships cannot survive is loss of communication and navigation awareness during an emergency.

Navigation and GMDSS power systems exist to ensure that when everything else fails, the ship can still:

transmit distress
receive instructions
maintain situational awareness
coordinate rescue

If these systems lose power, the casualty becomes silent and blind.

What navigation and comms power actually supports

These systems include:

ECDIS, gyro, GPS, radar processors
AIS and VDR interfaces
GMDSS radios (VHF, MF/HF, Inmarsat)
internal communication systems
emergency alarms and PA

They depend on:

UPS systems
dedicated battery banks
carefully managed DC supplies

🔧 Regulatory anchors (explicit)

SOLAS Chapter IV (GMDSS) requires:

uninterrupted power for distress and safety communications
main, emergency, and reserve power sources
defined minimum autonomy (typically 1–6 hours depending on vessel type)

IEC 60092-504 governs batteries and DC power for radio and navigation systems.

Failure to maintain autonomy is direct non-compliance.

UPS and battery autonomy — the weakest link

Navigation and GMDSS systems rely heavily on UPS autonomy. Problems arise when:

additional loads are added over time
batteries age unnoticed
autonomy calculations are not revisited
testing is limited to “power on” checks

A UPS that runs a radar for 30 minutes instead of 2 hours still “works” — until it doesn’t.

🔻 Real-World Case: Loss of Communications After Blackout — MV Viking Sky (2019)

During the casualty aboard MV Viking Sky, the vessel experienced:

total loss of propulsion
heavy weather conditions
reliance on emergency power and backup systems
intense dependence on communications during helicopter evacuation

While generators were eventually restarted, continuous availability of navigation and communication power was critical to coordinating rescue and preventing further loss of life.

Navigation power did not prevent the casualty.
It enabled survival.

Why comms power failures are often hidden

Communication systems may:

reboot silently
lose configuration
appear “on” but not transmit
fail selectively as batteries drop voltage

Crews often assume comms are available — until the distress call fails.

Professional ETO mindset

An experienced ETO asks:

How long can GMDSS transmit at full duty cycle?
What happens at low DC voltage?
Which systems drop out first?
Has this been tested under real load?

Communications are only as reliable as their weakest battery cell.

Knowledge to Carry Forward

Navigation and GMDSS power systems do not save ships — they save time, coordination, and lives. When these systems fail early, rescue becomes delayed, fragmented, or impossible.

Silence at sea is never benign.