Maritime Communication – RMN Networks & GMDSS (Lecture 3 + 4)

Motivation & Mind-Set

Opening Quote: “YOU CAN'T WIN PHYSICALLY IF YOU'RE LOSING MENTALLY.” — Billy Cox
• Emphasises psychological readiness for safe, effective maritime communication.
• Ethical dimension: complacency or poor morale can jeopardise lives at sea.

Royal Malaysian Navy (RMN) Communications Organisation

Primary Shore Nodes
• $\text{SKTLDM Lumut, SKTLDM Parit}$ – dedicated transmitters.
• $\text{SKTLDM Sitiawan}$ – transceiver hub.
• $\text{SKTLDM Kuantan Padang Hangus}$ – transmitter.
• $\text{Bukit Selang}$ – transceiver.
• $\text{SKTLDM Kota Kinabalu, SKTLDM Kuala Lumpur}$ – transceivers.
Three-Tier Command Hierarchy
1. HQ Fleet Operation Command (FOC) — strategic oversight of all naval regions and EEZ.
2. Area Commands (COMNAV 1, 2, 3) with geographically bounded responsibility:
  • COMNAV 1: $1^{\circ}\text{N} \rightarrow 8^{\circ}\text{N}$ latitude band.
  • COMNAV 2: $109^{\circ}\text{E} \rightarrow 121^{\circ}\text{E}$ longitude band.
  • COMNAV 3: Langkawi sector + adjacent EEZ.
3. Task Groups / individual units.
CHOP – Change of Operational Command
• Legal delegation allowing FOC/Area Commanders to retask or redeploy forces instantly.
• Preserves tactical control while enabling flexible mission assignment.

RMN Radio Nets (8 discrete nets)

Command Net – vertical command-and-control links.
HOAN (Harbour & On-scene Area Net) – rapid local comms ship↔ship / ship↔harbour.
SOAN (Ship On-scene Area Net) – automatic hailing when RMN ships sight each other or interact with MAF aircraft.
Exercise Net – communications during drills.
Control Net – real-time weapon-system direction & orders.
Reporting Net – free interchange of data for common operational picture (COP).
Tactical Net – manoeuvre orders & urgent tactical traffic.
(Implicit) Administrative/Logistics traffic handled through relevant nets above.

Pedagogical link: mirrors NATO standard ACP-127 net structures; familiarity aids multinational exercises.

Global Maritime Distress & Safety System (GMDSS)

Historical Context

Pre-GMDSS (18th–20th C): Manual Morse/visual signals → ambiguity & delayed rescue.
IMO adopted GMDSS under SOLAS IV; full enforcement $1\,\text{Feb}\,1999$ .
Mandatory for passenger ships & cargo ships >300\,\text{GT} on international voyages.

Core Objective

Guarantee any ship can:
1. Send distress alerts globally.
2. Receive MSI regardless of position.
Philosophy shift: $\text{Ship → Shore}$ alerting replaces ship-to-ship reliance; automated functions reduce human watch-keeping load.

Functional Requirements (SOLAS IV/Reg 7)

Distress alerting
Locating signals
MSI transmission/reception
General communications

GMDSS System Architecture

Terrestrial Layer:
• Coast Radio Stations (HF, MF, VHF) with DSC watch.
• NAVTEX medium-frequency MSI broadcast.
Satellite Layer:
• Inmarsat (A, B, C, F77) – $3\times8^{\circ}$ geostationary constellation.
• COSPAS-SARSAT $\text{LEO + GEOSAR}$ .
Rescue Coordination Centres (RCC/MRCC): integrate satellite LUT/MCC feeds with coast-station alerts for SAR tasking.

Approved GMDSS Components

1. Satellite Terminals

Inmarsat-C
• Two-way store-and-forward text/data, EGC MSI, distress at $1.6\,\text{GHz}$ .
• Ocean Regions: ${\text{AOR-E},\,\text{AOR-W},\,\text{IOR},\,\text{POR}}$ .
• Compact antenna + built-in GPS, printer, distress (SOS) button.
Inmarsat F77 (Fleet 77)
• Integrated voice/data/fax; four priority layers (Distress > Urgency > Safety > Routine).
• Meets latest IMO GMDSS voice requirements.
Legacy terminals Inmarsat-A/B/M/mini-M still seen but F77/C dominate GMDSS compliance.

2. NAVTEX

MF $518\,\text{kHz}$ (English); Regional language $490\,\text{kHz}$ ; HF $4209.5\,\text{kHz}$ .
Automatic printer logs MSI; station service radius ≈ $370\,\text{km}$ .
Message header format: $\text{ZCZC\;B}1\,\text{B}2\,\text{B}3\text{B}4$ where
• $\text{B}1$ = transmitter ID, $\text{B}2$ = subject indicator, $\text{B}3\text{B}4$ = serial no.

3. Digital Selective Calling (DSC)

Digitised calling on VHF Ch 70, MF 2187.5 kHz, HF distress freqs.
Functions: distress alert, alert relay, routine individual/group calls.
Distress button: auto-repeats until acknowledged; auto-injects GPS position.
MMSI database reduces hoax potential & speeds identification.

4. EPIRB (406 MHz / 1.6 GHz)

Float-free, auto-activate; transmits $\text{MCC-formatted}$ hexadecimal ID + GPS coords.
Instantaneous alert through Inmarsat GEOSAR or $\text{COSPAS-SARSAT}$ LEO constellation.

5. SART (9 GHz X-Band)

Passive transponder appears on radar as 12 dots → line → concentric arcs as range closes.
Operational: $\ge96\,\text{h}$ standby + $\ge8\,\text{h}$ active.

Regulatory & Carriage Requirements

SOLAS Functional Matrix

Ship shall be able to:
• Ship-to-shore distress via $\ge2$ independent services.
• Ship-to-ship distress, SAR coordination, locating signals.
• MSI & general communications, bridge-to-bridge.
Reserve Energy:
• With emergency generator → $\ge1\,\text{h}$ radio power.
• Without → $\ge6\,\text{h}$ .
• Independent of main propulsion & may double as emergency lighting power.

Sea Areas Definition

$\text{A1}$ ≈ VHF 20 nm from coast (continuous VHF DSC coverage).
$\text{A2}$ ≈ MF 100 nm from coast (continuous MF DSC).
$\text{A3}$ ≈ 70°N–70°S Inmarsat footprint.
$\text{A4}$ = polar + remote beyond A3.

Minimum Carriage (All Ships)

VHF DSC (Ch 70) + voice (Ch 16/13/6).
$1\,(<500\,GRT)$ or $2\,(>500\,GRT)$ SARTs.
$2$ portable VHF survival craft radios ( $3$ if >500 GRT).
NAVTEX receiver (where service exists) else EGC SafetyNET.
Float-free 406 MHz EPIRB.

Additional by Sea Area

A1 only: minimum set above.
A1 + A2: + MF radio (2187.5 kHz DSC & 2182 kHz voice) + MF DSC watch receiver.
A1 + A2 + A3 choose either:
• Inmarsat B/C/Fleet 77 + MF suite, or
• Full MF/HF set (1.6–27.5 MHz) with DSC watch on ${2187.5,8414.5,\text{one of }4207.5/6312/12577/16804.5}\text{ kHz}$ + Inmarsat C.
A4 (Polar): MF/HF radio with DSC + Inmarsat C (recognising partial Inmarsat coverage) or alternative recognised polar satellite service.

Malaysian Implementation of GMDSS

Operational since $1\,\text{Aug}\,2000$ .
13 VHF-DSC coast stations (Ch 70) & 3 MF-DSC stations (2187.5 kHz) remotely monitored by MRCC Port Klang.
Coverage creates national Sea Area A1 & A2 zones (see reference map).
Example coast station data:
• Gunung Jerai $05^{\circ}47'\text{N}\,100^{\circ}26'\text{E}$ , MMSI 005330001, range 95 nm.
• Kota Kinabalu $06^{\circ}02'\text{N}\,116^{\circ}12'\text{E}$ , MMSI 005330013, range 75 nm.
Practical implication: Malaysian-flag vessels in littoral waters can rely on national SAR assets without resorting to MF/HF long-range alerts.

Maritime Safety Information (MSI) & WWNWS

MSI types: navigational warnings, meteorological warnings/forecasts, other urgent safety messages.
Disseminated through: NAVTEX, Inmarsat SafetyNET, HF NBDP broadcasts.
World-Wide Navigational Warning Service: 21 NAVAREAs numbered I–XXI; coordinated by IMO/IHO.
• Example: NAVAREA I = UK (Eastern Atlantic); NAVAREA XIV = South Pacific (NZ).
Ships must maintain MSI receivers tuned to their current NAVAREA.

Distress, Urgency & Safety Procedures

Distress (MAYDAY)
• Grave & imminent danger; highest priority.
• Obligation: all stations cease interference, monitor, render assistance.
Urgency (PAN PAN)
• Very urgent message concerning safety of ship/person (e.g.
loss of steering).
Safety (SECURITÉ)
• Navigational/met warnings of importance to shipping (e.g.
derelict container sighted).
Ethical note: misuse criminally liable; correct use preserves life at sea.

Practical & Philosophical Implications

Automation reduces human error but demands rigorous equipment maintenance & crew training.
GMDSS fosters international interoperability—essential in multinational SAR (e.g.
MH370 search).
Environmental factor: prompt distress alert limits pollution from wrecks due to faster salvage.
Cybersecurity emerging issue: DSC spoofing or Inmarsat terminal hacking could generate false alerts; IMO guidelines evolving.

Exam Tips & Connections

Memorise DSC distress sequence $\text{PRESS 5 s}$ & information auto-sent: MMSI, position, nature of distress code.
Link RMN net types to NATO C2 taxonomy for comparative questions.
Be able to sketch Sea Area diagram with radii (20 nm A1, 100 nm A2, 70° lat A3).
Understand that reserve energy hour count depends on presence of emergency generator—likely MCQ topic.
Remember overlap: NAVTEX >518 kHz global English; 490 kHz local language; 4209.5 kHz HF.

Closing Motivation

Quote: “STOP WAITING FOR THINGS TO HAPPEN. GO OUT AND MAKE THEM HAPPEN.”
• Take-away: proactive communication drills & equipment checks are as vital as theoretical knowledge for exam & real-world maritime safety.