Why Standard Communication Fails at Sea
The maritime workplace is one of the most challenging environments for reliable communication. Standard mobile phones are dangerously inadequate offshore, not just inconvenient.
The Unique Dangers
Engine, winch and machinery noise can drown out verbal commands. Saltwater spray and driving rain demand rugged, waterproof devices with a high IP rating. Steel bulkheads and cargo holds create dead zones that block standard radio and cellular signals entirely.
Why Phones Specifically Fail
- No coverage: cellular signals disappear a few kilometres from the coast.
- Lack of durability: consumer phones aren't built for wet, rough, noisy vessel conditions.
- Too slow for emergencies: dialling a number is far too slow for a man overboard situation where seconds count.
- No broadcast function: phones can't provide the instant, one-to-many communication needed to coordinate a crew.
A vessel relying on phones alone may also miss vital Maritime Safety Information broadcast through official channels, jeopardising the safety of the whole crew.
Core Communication Technologies
VHF Marine Radio
The cornerstone of ship-to-ship and ship-to-shore communication, and a legal requirement for most commercial vessels to monitor the international distress Channel 16. Modern VHF radios with Digital Selective Calling (DSC) can send an automated digital distress alert, including vessel identity and position, at the press of a button.
Onboard Two-Way Radios (UHF/DMR)
UHF signals penetrate a ship's steel structure more effectively than VHF, ensuring reliable contact from the engine room to the deck. DMR radios add strong noise cancellation, useful for coordinating mooring, cargo handling, and emergency response.
Satellite Communication
Once beyond VHF and cellular range, satellite communication becomes essential. Satellite phones provide voice and data connectivity from anywhere, while satellite messengers offer tracking, pre-set check-ins, and basic texting for non-urgent updates.
Emergency Beacons: EPIRBs and PLBs
These are for situations of grave and imminent danger only, broadcasting a distress signal to the Cospas-Sarsat satellite system to alert search and rescue. EPIRBs are registered to the vessel and can activate automatically when submerged. PLBs are smaller, registered to an individual, and must be manually activated, useful for crew who may be separated from the vessel.
Building a Communication Safety Plan
- Assess risks and identify black spots: walk the vessel to identify zones with high noise or signal obstruction, and analyse needs for high-risk tasks like crane operations or confined space entry.
- Choose the right mix of technology: a layered approach, UHF/DMR for internal crew communication, VHF for external communication with other vessels and Coastguard, satellite beyond coastal range, provides genuine redundancy.
- Implement clear protocols and training: standard radio etiquette, universally understood key phrases, and regular drills covering everything from internal alerts to formal Mayday calls.
- Schedule regular maintenance: daily battery charging, weekly antenna and cabling inspections for salt corrosion, and full radio checks before leaving port.
Advanced Solutions
Man Overboard (MOB) Alert Systems
Personal MOB devices worn by crew activate automatically on submersion, triggering onboard alarms and logging precise GPS coordinates, drastically reducing search time in NZ's cold waters.
Integrated GPS Tracking
Fleet managers can monitor vessel locations in real time, while personal GPS trackers pinpoint a worker's location on a large vessel or port facility, invaluable data during a rescue.
On-Deck PA Systems and Loudhailers
On a noisy deck, standard voice communication is often impossible. PA systems and loudhailers broadcast clear instructions that cut through engine and machinery noise, ensuring critical messages reach everyone simultaneously.
Getting the Right System in Place
Mobile Systems Limited is 100% New Zealand owned and based in Mount Maunganui, with over 25 years supplying and supporting maritime communication systems. We supply VHF, UHF, satellite and EPIRB/PLB solutions for ports, vessels and commercial fleets, with nationwide installation and support.
