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

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.

• Regulations 19 & 20 — the statutory equipment mandates.
• ≥ 300 GT — the international threshold for AIS and LRIT carriage.
• ≥ 3,000 GT — dual radar (X and S band) plus VDR.
• All ships — universal application of Chapter V.
• 3 stages — the BNWAS watch alarm escalation.

SOLAS Chapter V Navigational Equipment Carriage Schedule

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 — the AIS 1 and AIS 2 VHF frequencies.
• SOTDMA — self-organizing time division multiple access.
• 2,250 slots/minute — time frame slot capacity.
• 2 seconds to 3 minutes — dynamic and kinematic update rates.
• 12.5 watts — Class A RF transmission power.

AIS Dynamic Reporting Rate Breakdown (Class A)

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.

• 4× daily — standard reporting every 6 hours.
• 1,000 NM — the coastal State tracking radius.
• SOLAS V Regulation 19-1 — the statutory convention mandate.
• IDE & DDP — the international data routing hub.
• 15 minutes — maximum polled high-rate frequency.

Comparison: AIS vs LRIT Tracking Systems

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 for 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.

Oral Examination Viva Bank: SOLAS Chapter V

1. 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.

2. 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.

3. 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).

4. 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.