SOLAS Ch. IV (MSC.496(105)) & Ch. V · GMDSS, LRIT & Bridge
GMDSS & Bridge Equipment Testing Checklist: Daily, Weekly & Monthly Logs
The navigation bridge is the first stop on almost every Port State Control, USCG, SIRE 2.0 (Chapter 4) and RightShip RISQ 3.2 (Section 6) inspection. Following the entry into force of IMO Resolution MSC.496(105) (modernized SOLAS Chapter IV) on 1 January 2024 and IMO Resolution A.1206(34) on 1 January 2026, inspectors scrutinize the GMDSS Radio Logbook, 24V DC reserve battery capacity records, LRIT Conformance Test Reports, BNWAS, and SOLAS V/26 pre-departure steering gear tests.
This guide covers the mandatory daily, weekly, monthly and annual GMDSS tests, bridge navigational equipment checks, and the practical demonstrations deck officers are asked to perform.
Updated · Written by SeaReady in our own words. Not affiliated with OCIMF, RightShip, CDI, any MoU or any administration — always check the current official documents.
1. Mandatory GMDSS Test Schedule: Daily, Weekly, Monthly & Annual (SOLAS Ch. IV)
Every SOLAS ship must carry a GMDSS Radio Logbook (SOLAS Regulation IV/17) on the bridge, kept up to date by the designated GMDSS radio officer (typically the 2nd or 3rd Officer) and inspected and signed regularly by the Master:
| Test Interval | Frequency & Logbook Requirement | Mandatory GMDSS Equipment Checks |
|---|---|---|
| Daily GMDSS Tests (SOLAS IV/15 & STCW Code A-VIII/2) | Every 24 hours (recorded in the GMDSS Radio Logbook) | Test the proper functioning of the DSC (Digital Selective Calling) facilities on VHF (Ch. 70) and MF/HF without radiating signals by using the built-in internal self-test, check the GMDSS reserve battery on-load and off-load voltage (charging/discharging current), and check that all GMDSS printers (if fitted) have adequate paper. |
| Weekly GMDSS Tests (Live MF/HF DSC, Two-Way VHF & Survival Craft) | Every 7 days (recorded in the GMDSS Radio Logbook) | Perform a live MF/HF DSC test call with a Coast Station (where within range, or at the first opportunity), test the portable two-way Survival Craft VHF radiotelephones on a channel other than Ch. 16 (with the yellow/orange primary lithium emergency batteries kept sealed with intact expiry dates and the rechargeable training batteries used for tests), and start the emergency generator if it supplies GMDSS. |
| Monthly GMDSS & Bridge Survival Craft Tests (EPIRB, SART/AIS-SART & Batteries) | Every month (recorded in the GMDSS Radio Logbook & Deck Logbook) | Test the 406 MHz satellite EPIRB using its built-in self-test (checking battery & HRU expiry dates and AIS homing function under MSC.471(101)), test every radar SART (9 GHz) or AIS-SART in self-test mode, inspect the physical condition of all aerials and insulators, and check the specific gravity / cell voltages and connections of the GMDSS reserve battery bank. |
| Annual GMDSS & VDR Performance Tests (SOLAS IV/15.9 & V/18.8) | Within the ±3-month Cargo Ship Safety Radio / Safety Equipment window | An approved Radio Surveyor must complete the annual GMDSS comprehensive test (including 406 MHz EPIRB annual testing under SOLAS IV/15.9 and capacity discharge testing of the GMDSS reserve battery), and an approved service technician must issue the annual Voyage Data Recorder (VDR / S-VDR) Certificate of Compliance (including the float-free capsule EPIRB). |
- GMDSS Sea Areas A1, A2, A3 & A4 vs Form R: Cross-check that the equipment ticked on your Record of Equipment for Cargo Ship Safety Radio (Form R) matches the Sea Areas listed on your Safety Radio Certificate (including whether the Recognized Mobile Satellite Service is Inmarsat-C or Iridium under MSC.496(105)) and that the ship’s ITU List V (List of Ship Stations and Maritime Mobile Service Identity Assignments) and List IV (List of Coast Stations and Special Service Stations) are the current editions.
- Distress procedure & false-alert cancellation placards: Confirm that clear, laminated placards showing the ship’s Call Sign, MMSI, IMO Number and Inmarsat/Iridium IDs are posted immediately beside the GMDSS console, covering both How to Transmit a Distress Alert and How to Cancel a False Distress Alert (ITU Res. 349).
2. LRIT, BNWAS, VDR, Compass Error & SOLAS V/26 Pre-Departure Tests
Alongside the ECDIS and berth-to-berth passage plan, bridge inspectors verify the operational status and log records of core SOLAS Chapter V systems:
| Bridge System / Regulation | Required Frequency / Setting | Inspector Verification & Detention Traps |
|---|---|---|
| SOLAS V/19-1 Long-Range Identification and Tracking (LRIT) | Continuous 6-hourly automatic position transmission + Conformance Test Report | Under IMO Res. A.1206(34), a non-functioning or switched-off LRIT terminal without immediate Flag State notification and GMDSS log entry is an explicit ground for PSC detention (Action Code 30). Verify the LRIT Conformance Test Report matches the ship’s MMSI and IMO number. |
| Bridge Navigational Watch Alarm System (BNWAS — SOLAS V/19.2.2.3 & MSC.128(75)) | Automatic / operational whenever the ship is underway at sea (3–12 min dormant period) | Inspectors check that the BNWAS key or password is held strictly by the Master, the dormant period is set between 3 and 12 minutes, Stage 1 (bridge visual/audible), Stage 2 (officer cabins/back-up officer) and Stage 3 (general crew alarm) transfer timers work, and the system was never left switched off at sea. |
| SOLAS V/26 Steering Gear Pre-Departure Tests (12 Hours Before Departure) | Tested within 12 hours before departure (recorded in the Official / Deck Logbook) | Test main and auxiliary steering gear power units, remote steering control systems from all bridge conning positions, emergency power supply, rudder angle indicators against actual rudder stock indicator, power-failure alarms, and steering-gear room communications. |
| Magnetic Compass Deviation Book, Gyro Error Log & Radar Performance Monitors | Compass error once per watch (and after major course alterations) · Annual compass swing | Verify the Magnetic Compass Deviation Card is valid (typically within 12–24 months or when deviations exceed 5°), the Compass Observation Book has regular azimuth/amplitude entries across all OOW watches, and X-band (9 GHz, for SART detection) and S-band (3 GHz) radar performance monitors (PM) are logged. |
3. Practical Bridge Demonstrations Every OOW Must Be Ready to Show
Before arrival in port, the Master should verify that every Officer of the Watch (Master, Chief Officer, 2/O and 3/O) can demonstrate the following five bridge checks without hesitation:
- 1. Switching GMDSS from AC mains to 24V DC reserve battery: Show the AC/DC changeover switch, read out the on-load DC voltage and current, and show the emergency GMDSS console light situated above the VHF/MF-HF DSC controller.
- 2. Retrieving VDR / S-VDR status and alarm history: Confirm the Bridge VDR alarm panel shows zero active faults (green normal status), explain how to press the Save / Incident Backup button after a near-miss or incident so the 12-hour/48-hour loop is not overwritten, and produce the valid annual VDR Certificate of Compliance.
- 3. Testing the 406 MHz EPIRB and 9 GHz SART / AIS-SART: Demonstrate the monthly self-test switch on the float-free EPIRB and SART without transmitting a live distress signal, and point out the hydrostatic release unit (HRU) and battery expiry dates.
- 4. Checking NAVTEX / EGC MSI station and message filters: Show that the NAVTEX receiver (518 kHz international English and 490 kHz local where applicable) and EGC (SafetyNET / SafetyCast) terminal are programmed for the current NAVAREA/METAREA coastal stations, and that active navigational warnings are plotted on the ECDIS.
Questions seafarers ask
What modernized GMDSS rules entered into force on 1 January 2024 under IMO Resolution MSC.496(105)?
IMO Resolution MSC.496(105) comprehensively revised SOLAS Chapter IV (Radiocommunications) effective 1 January 2024: it replaced references to "Inmarsat" with generic "Recognized Mobile Satellite Service (RMSS)" (covering Inmarsat and Iridium GMDSS Sea Area A3 configurations), removed obsolete NBDP (Narrow-Band Direct Printing radio telex) carriage requirements, integrated AIS-SART and radar SART into Chapter IV alongside Chapter III, and updated the Record of Equipment for Cargo Ship Safety Radio (Form R).
Why must crew never break the seal on the primary lithium battery of a two-way Survival Craft VHF radio during weekly tests?
Under SOLAS Chapter III/IV and MSC.149(77), each portable two-way Survival Craft VHF radio must have a dedicated primary (non-rechargeable) lithium battery sealed for emergency use only, with an unexpired shelf-life date, PLUS a separate rechargeable NiCd/NiMH/Li-ion battery on a bridge charger for daily/weekly testing and routine onboard use. Breaking the seal on the emergency primary battery invalidates its guaranteed 8-hour emergency capacity and triggers an immediate PSC / SIRE 2.0 deficiency.
What happens during a Port State Control inspection if the 2/O or 3/O cannot demonstrate a GMDSS reserve battery test or false distress alert cancellation?
Under IMO Resolution A.1206(34) (2025 PSC Procedures), Port State Control officers regularly ask a deck officer holding a GMDSS General Operator’s Certificate (GOC) to switch the GMDSS console from AC mains to the 24V DC reserve battery, initiate a DSC internal self-test, show the last weekly live MF/HF Coast Station ACK in the GMDSS Radio Logbook, and explain the exact procedure in ITU Resolution 349 (or MSC/Circ.862) for cancelling an inadvertent false distress alert on VHF DSC, MF/HF DSC, RMSS or 406 MHz EPIRB.
How is the GMDSS 24V DC reserve battery annual capacity test (1-hour or 6-hour requirement) verified?
Under SOLAS Regulation IV/13.2, the GMDSS reserve source of energy must supply the VHF, MF/HF or RMSS installation, basic GPS input and emergency GMDSS light for at least 1 hour (if the ship’s emergency generator automatically supplies GMDSS within 1 minute under SOLAS II-1/42 or 43) or 6 hours (if not supplied by an compliant emergency generator). Under SOLAS IV/13.6.2, the capacity of the reserve battery must be checked at intervals not exceeding 12 months using an appropriate method (when the ship is not at sea).
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Related guides
- ECDIS & passage planning checklistBerth-to-berth passage planning (A.893(21)), ECDIS safety contour, UKC/squat, ENCs and VDR checks.
- PSC inspection checklistThe inspection start to finish, every deficiency area, risk windows and the CIC.
- LSA & FFA maintenance intervals checklistWeekly, monthly, annual and 5-yearly LSA/FFA maintenance intervals under SOLAS III/20 and MSC.1/Circ.1432.
- SIRE 2.0 inspection checklistChapter by chapter: what the inspector looks at and the evidence to have ready.
- AIS, LRIT, dark fleet & VDR compliance guideSOLAS V/19.2.4 Universal AIS (MSC.570(109)), Res. A.1192(33) anti-dark fleet, LRIT CTR and SOLAS V/20 VDR annual CoC.
- BNWAS bridge navigational watch alarm system SOLAS guideSOLAS V/19 & MSC.128(75) BNWAS rules, 3–12m dormant cycles, Stage 1–3 alarms, MSC.1/Circ.1474 Manual ON mode and VDR logging.