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SOLAS Chapter V — Safety of Navigation (AIS, LRIT & VDR)

Carriage requirements and the three key fittings: the Automatic Identification System, Long-Range Identification and Tracking, and the Voyage Data Recorder.

10 min read
Intermediate
Safety
Key Principles at a Glance 6 points
  • Unlike most SOLAS chapters which apply only to international trading vessels, SOLAS Chapter V applies broadly to all ships on all voyages (with specific Flag State exemptions).
  • Regulation 19 sets a tiered carriage schedule for navigational systems: magnetic compass, gyro compass, 9 GHz (X-band) and 3 GHz (S-band) radars, ARPA, ECDIS, speed log, echo sounder, and BNWAS.
  • Class A AIS is mandatory on all passenger ships and cargo ships ≥ 300 GT on international voyages (≥ 500 GT domestic), broadcasting dynamic, static, and voyage data via SOTDMA on 161.975 MHz and 162.025 MHz.
  • LRIT (SOLAS V Reg 19-1) automatically transmits vessel position, identity, and timestamp at least four times daily (every 6 hours) via satellite to Flag, Port, and Coastal States within 1,000 NM.
  • The Voyage Data Recorder (VDR) under Regulation 20 preserves at least 48 hours of bridge audio, radar, ECDIS, and sensor telemetry within a crash-hardened fixed capsule (surviving 1,000°C for 1 hour and 6,000 m submersion).
  • Fixed VDR capsules carry a 37.5 kHz underwater acoustic beacon (pinger) operating continuously for 30 to 90 days upon water immersion to facilitate deep-sea recovery.

1. SOLAS Chapter V: Safety of Navigation & Carriage Requirements

SOLAS Chapter V establishes the statutory rules governing operational navigation, bridge watchkeeping, nautical chart carriage, and electronic sensor redundancy. While many SOLAS chapters restrict their scope strictly to international voyages, Chapter V applies universally to all ships on all voyages, placing overriding statutory authority in the hands of the Master to safeguard the vessel, crew, and marine environment.

Reg 19 & 20 Statutory Equipment Mandates
≥ 300 GT AIS & LRIT International Threshold
≥ 3,000 GT Dual Radar (X & S Band) + VDR
All Ships Universal Chapter V Application
3 Stages BNWAS Watch Alarm Escalation
INTEGRATED BRIDGE SYSTEM (IBS) REGULATION 19 EQUIPMENT SUITE SOLAS V Reg 19 & 20 • Sensor Interfacing • Dual ARPA Radar • ECDIS Main/Backup • VDR Data Tap X-BAND RADAR (3cm) MAIN ECDIS (ENC) HDG 000° STW: 16.4 kt DEPTH: 42 m RUDDER: 0° CONNING / AUTOPILOT BACKUP ECDIS S-BAND RADAR (10cm) AIS CLASS A BNWAS (12 min) DUAL GPS / DGPS ECHO / SPEED LOG VDR LIVE CARRIAGE MILESTONES: All ships: Magnetic compass • ≥ 300 GT: Class A AIS + LRIT • ≥ 500 GT: Gyro compass + 9 GHz Radar • ≥ 3,000 GT: 3 GHz S-Band Radar + ECDIS + VDR.
Figure 1: SOLAS Regulation 19 Integrated Bridge System (IBS) Suite. Illustrates statutory sensor integration: dual ARPA radars (9 GHz X-band for sharp resolution; 3 GHz S-band for sea/rain clutter penetration), dual ECDIS workstations, conning telemetry, and overhead integration of AIS, BNWAS, GNSS, and Voyage Data Recorder (VDR).

SOLAS Chapter V Navigational Equipment Carriage Schedule

Vessel Tonnage Threshold Mandatory Navigational Systems & Sensor Fittings (Reg 19 & 20)
All Ships (Universal) Properly adjusted standard magnetic compass, pelorus, chart catalogue/nautical publications, daylight signalling lamp (Aldis lamp), radar reflector (if < 150 GT).
150 GT and above Spare magnetic compass bowl, bridge navigational watch alarm system (BNWAS), steering compass heading repeater.
300 GT and above (International) Class A AIS (Automatic Identification System), LRIT (Long-Range Identification and Tracking satellite reporting unit), echo sounder, 9 GHz (X-band) radar, speed and distance log through the water.
500 GT and above Gyro compass and gyro repeaters, Electronic Plotting Aid (EPA) or Automatic Radar Plotting Aid (ARPA), rudder angle indicator, propeller pitch/revolution indicators.
3,000 GT and above Second independent radar (3 GHz S-band or second 9 GHz X-band), dual Electronic Chart Display and Information System (ECDIS) with independent power backup, and Voyage Data Recorder (VDR).
10,000 GT and above Automatic Radar Plotting Aid (ARPA) on both radars, heading/track control system (autopilot), speed log measuring speed over ground (SOG) and speed through water (STW).

2. AIS — Automatic Identification System

The Automatic Identification System (AIS) is an autonomous broadcast transponder operating in the VHF maritime mobile band. AIS automatically exchanges ship identification, kinematic vector data, and voyage details with nearby vessels, Vessel Traffic Service (VTS) shore radars, and low-earth orbit satellites (Satellite-AIS / S-AIS).

161.975 / 162.025 MHz AIS 1 / AIS 2 VHF Frequencies
SOTDMA Self-Organizing Time Division Multiple Access
2,250 Slots/min Time Frame Slot Capacity
2s to 3 min Dynamic Kinematic Update Rates
12.5 Watts Class A RF Transmission Power
AIS SOTDMA TIME FRAME SYNCHRONIZATION & DATA CLASSIFICATION ITU-R M.1371 • 2,250 Slots per Minute • GPS UTC Synchronization • Static, Dynamic & Voyage Data SOTDMA 1-MINUTE TIME FRAME (2,250 SLOTS) S1 S2 S3 S4 S5 ... S2249 S2250 26.66 ms VHF FREQUENCY PAIRS (TDMA): • AIS 1: 161.975 MHz (VHF Ch 87B) • AIS 2: 162.025 MHz (VHF Ch 88B) Continuous alternating broadcast across both channels avoids interference. Sync source: GNSS UTC Pulse-Per-Second (PPS) prevents clock drift. SOTDMA autonomously resolves slot collision without shore master. 1. STATIC DATA (EVERY 6 MIN OR ON REQUEST) • MMSI (9 digits) • IMO Ship ID • Call Sign • Ship Name • Length & Beam • Type of Ship • GNSS Antenna Location (A/B/C/D offsets) Programmed at vessel commissioning; tamper-protected by password. 2. DYNAMIC DATA (EVERY 2s TO 3 MIN AUTONOMOUS) • Ship Position (Lat/Long ±0.0001 min) • Time in UTC • COG • SOG • True Heading • Rate of Turn (ROT) • Navigational Status (Underway/Anchored) Updated dynamically based on speed log, gyro compass & GNSS. 3. VOYAGE-RELATED DATA (EVERY 6 MIN / MANUAL) • Maximum Present Draught (decimetres) • Hazardous Cargo Type (IMDG) • Destination & Estimated Time of Arrival (ETA in UTC) • Persons on Board Entered manually by Bridge Watchkeeper prior to departure. DYNAMIC REPORTING CADENCE: Anchored: 3 min • 0–14 kt: 10s • 0–14 kt changing course: 3.3s • 14–23 kt: 6s • 14–23 kt changing course: 2s • >23 kt: 2s.
Figure 2: AIS SOTDMA Time Division Multiple Access & Data Classification. Operating across VHF channels AIS 1 (161.975 MHz) and AIS 2 (162.025 MHz), SOTDMA synchronizes transmission into 2,250 distinct 26.66-millisecond time slots every minute using GPS UTC timing. Shows the three statutory data categories: Static, Dynamic, and Voyage-related information.

AIS Dynamic Reporting Rate Breakdown (Class A)

Vessel Dynamic Condition / Speed Autonomous Reporting Interval
Ship at anchor or moored (not moving faster than 3 knots) Every 3 minutes
Ship underway at 0 to 14 knots (steady course) Every 10 seconds
Ship underway at 0 to 14 knots (changing course) Every 3.3 seconds
Ship underway at 14 to 23 knots (steady course) Every 6 seconds
Ship underway at 14 to 23 knots (changing course) Every 2 seconds
Ship underway at > 23 knots (steady or changing course) Every 2 seconds

3. LRIT — Long-Range Identification and Tracking

Adopted under SOLAS Regulation V/19-1 in 2006, Long-Range Identification and Tracking (LRIT) is a global maritime security and tracking regime. Unlike VHF-based AIS which operates within line-of-sight (20–30 NM), LRIT utilizes satellite terminals (Inmarsat-C or Iridium) to transmit encrypted position reports directly to Flag Administrations, Port Authorities, and Coastal States across global oceanic distances.

4x Daily Standard Reporting Rate (Every 6 Hours)
1,000 NM Coastal State Tracking Radius
SOLAS V Reg 19-1 Statutory Convention Mandate
IDE & DDP International Data Routing Hub
15 Minutes Max Polled High-Rate Frequency
LRIT GLOBAL DATA ARCHITECTURE & ENTITLED USER JURISDICTIONS SOLAS V Reg 19-1 • Inmarsat-C/Iridium Burst • CSP/ASP Validation • Flag, Port, Coastal & SAR Access SHIP TERMINAL Inmarsat-C / Iridium 4x/day auto report CSP / ASP Comms Service & Application Provider LRIT DATA CENTRE (NDC / RDC) Stores & Processes Position Packets INTERNATIONAL DATA EXCHANGE (IDE) DDP (Data Distribution Plan) Routes data to entitled states Zero Cost to Shipowner 1. FLAG STATE Entitled to receive reports for its ships anywhere globally. 2. PORT STATE Tracks inward vessels that have declared entry to its ports. 3. COASTAL STATE Tracks vessels passing off its coast within 1,000 NM. 4. SAR SERVICES Accesses positional data free of charge during distress. CONFIDENTIALITY & CHARGING: Unlike AIS which broadcasts openly to all receivers in VHF range, LRIT transmissions are encrypted point-to-point data packets. The ship incurs no satellite communication charges for LRIT transmissions.
Figure 3: Global LRIT System Architecture & Entitlement Access. The shipborne satellite terminal transmits encrypted reports (ship identity, GNSS coordinates, UTC timestamp) every 6 hours through Communication Service Providers (CSP) to National/Regional Data Centres. The International LRIT Data Exchange (IDE) routes data securely to Flag, Port, Coastal (within 1,000 NM), and SAR authorities.

Comparison: AIS vs LRIT Tracking Systems

Feature / Parameter Automatic Identification System (AIS) Long-Range Identification & Tracking (LRIT)
Governing Regulation SOLAS Chapter V, Regulation 19 SOLAS Chapter V, Regulation 19-1
Communication Medium VHF Maritime Mobile Band (161.975 / 162.025 MHz) Satellite Communications (Inmarsat-C / Iridium)
Effective Range Line-of-sight: 20 to 30 NM (extended by S-AIS satellites) Global oceanic coverage (worldwide anywhere on earth)
Transmission Type Open broadcast (unencrypted; received by any VHF station) Encrypted point-to-point data packets
Reporting Frequency Dynamic: every 2 seconds to 3 minutes; Static: every 6 min Standard: 4 times per day (every 6 hours); pollable to 15 min
Primary Objective Tactical collision avoidance & coastal Vessel Traffic Service (VTS) Strategic maritime domain security, coastal monitoring & SAR

4. VDR — Voyage Data Recorder

SOLAS Chapter V Regulation 20 mandates the carriage of a Voyage Data Recorder (VDR) (or Simplified VDR / S-VDR on existing cargo vessels). Operating identically to an aircraft flight data recorder ("black box"), the VDR continuously records bridge voice, radar screenshots, ECDIS chart vectors, and machinery sensor parameters into survivable capsules to reconstruct marine accidents.

VDR Six-Item Record Drill (Q74)

After an incident the last stored hours come out of the shock/pressure/heat-proof storage unit. Recite the six recorded items as move — talk — alarm — close: ship position; date, time, speed; VHF radio communication; full alarm history; watertight and weathertight door status as shown on the bridge; bridge audio including the bridge wings.

≥ 48 Hours Continuous Recording Capacity
1,000°C / 1 Hour Fireproof Thermal Rating
6,000 m / 60 MPa Deep-Sea Hydrostatic Resistance
50g / 11 ms Impact Shock Deceleration Limit
37.5 kHz / 90 Days Underwater Acoustic Locator Beacon
VDR CRASH-HARDENED FIXED CAPSULE & SENSOR ACQUISITION ARCHITECTURE SOLAS V Reg 20 & Resolution MSC.333(90) • 48-Hour Solid State Memory • 1,000°C Fire Barrier • 37.5 kHz Beacon CRASH-HARDENED FIXED CAPSULE THERMAL BARRIER 1,000°C for 60 min SOLID STATE MEMORY ≥ 48 Hours Data ULB 37.5 kHz 90-Day Pinger RELEASE CRADLE MANDATORY RECORDED DATA CHANNELS BRIDGE AUDIO & VHF COMMS: Min 2 dedicated omni mics + VHF Tx/Rx audio RADAR & ECDIS SCREENSHOTS: Direct video frame grab every 15 seconds KINEMATICS (GPS / GYRO / LOG): Lat/Long, True Heading, STW, SOG, Depth STEERING & RUDDER STATUS: Rudder order & actual rudder response angle MAIN ENGINE & THRUSTERS: Telegraph order, shaft RPM, pitch, bow thruster ALARMS & WATER INTEGRITY: Watertight/fire doors, hull stress, bilge alarms TEST SURVIVABILITY LIMITS: Fire test: 1,000°C for 1 hour + 260°C for 10 hours • Impact: 50g shock for 11 ms • Penetration: 250 kg pin drop from 3 m • Deep immersion: 6,000 m (60 MPa) for 30 days.
Figure 4: Voyage Data Recorder (VDR) Crash-Hardened Capsule & Sensor Telemetry Architecture. Shows the triple-barrier survivable enclosure housing solid-state memory (≥ 48 hours recording under Resolution MSC.333(90)), the 37.5 kHz underwater locator beacon (90-day transmission life), and the multi-channel sensor feed capturing bridge audio, radar imagery, ECDIS chart vectors, engine telegraph, and hull stress.

Oral Examination Viva Bank: SOLAS Chapter V

To which vessels does SOLAS Chapter V apply, and how does this differ from other SOLAS chapters?
Unlike most SOLAS chapters which apply strictly to cargo ships ≥ 500 GT and passenger ships engaged on international voyages, SOLAS Chapter V applies to all ships on all voyages (including domestic coastal voyages, fishing vessels, and pleasure craft, subject to specific Administration exemptions under Regulation 1). Regulation 19 establishes specific equipment thresholds based on gross tonnage.
What data is broadcast by an AIS Class A transponder, and what are the update rates?
AIS broadcasts three categories: Static data (MMSI, IMO number, call sign, name, dimensions) every 6 minutes; Dynamic data (position, UTC time, COG, SOG, heading, rate of turn, nav status) reported autonomously every 2 seconds to 3 minutes based on vessel speed and course alteration; and Voyage-related data (draught, IMDG cargo category, destination, ETA) every 6 minutes or when updated by the watchkeeper.
How does LRIT function, and who is entitled to receive vessel location reports?
LRIT (SOLAS V Reg 19-1) automatically transmits the ship’s identity, GNSS coordinates, and UTC timestamp every 6 hours (4 times daily) via satellite to the National Data Centre. Four entities are entitled to receive data: (1) the Flag State (tracks own ships globally), (2) the Port State (tracks ships entering its ports), (3) the Coastal State (tracks ships passing within 1,000 NM of its coast), and (4) SAR authorities (tracks ships in a distress area free of cost).
What are the recording duration and survivability requirements for a modern VDR?
Under Resolution MSC.333(90), modern VDRs must continuously record for at least 48 hours into both a fixed crash-hardened capsule and a float-free capsule. The fixed capsule must withstand an impact of 50g for 11 ms, a continuous fire of 1,000°C for 1 hour (and 260°C for 10 hours), a penetration test with a 250 kg steel pin dropped from 3 m, and deep-sea hydrostatic immersion at 6,000 metres (60 MPa) for 30 days. An underwater locator beacon (37.5 kHz) must ping continuously for 90 days.