SOLAS Chapter IV GMDSS: Radio Equipment, EPIRB, SART & VHF Requirements for Ships

Reliable communication is one of the most important elements of ship safety. During a distress situation, a vessel must be capable of transmitting distress alerts, receiving maritime safety information and communicating with other vessels, coast stations and search-and-rescue authorities.

The Global Maritime Distress and Safety System (GMDSS) provides the international framework for these communications.

The requirements for GMDSS are incorporated into SOLAS Chapter IV – Radiocommunications. The International Maritime Organization (IMO) states that applicable passenger ships and cargo ships of 300 gross tonnage and above on international voyages are required to carry specified radiocommunication equipment, including EPIRBs and SARTs. International Maritime Organization

For ship owners, ship managers, Masters, Chief Engineers and technical superintendents, understanding the requirements for VHF, DSC, EPIRB, SART, MF/HF, NAVTEX, satellite communication equipment and GMDSS batteries is essential for maintaining vessel compliance and emergency readiness.

This guide explains the major SOLAS Chapter IV GMDSS requirements, the purpose of important GMDSS equipment and the role of a professional GMDSS Radio Survey & Inspection Service.

What Is GMDSS?

GMDSS stands for Global Maritime Distress and Safety System.

It is an internationally recognized communication and safety system designed to ensure that a vessel in distress can:

• Send a distress alert to shore and/or other vessels
• Receive distress and safety information
• Communicate with rescue coordination authorities
• Communicate with nearby vessels
• Receive Maritime Safety Information (MSI)
• Support search-and-rescue operations
• Maintain communication using appropriate radio and satellite systems

GMDSS combines different communication technologies depending on the vessel's trading area.

These may include:

• VHF radio
• VHF DSC
• MF radio
• HF radio
• MF/HF DSC
• Satellite communication equipment
• NAVTEX
• EPIRB
• Radar SART
• AIS-SART
• Portable two-way VHF radios
• GMDSS reserve batteries
• Associated antennas, cables and power supplies

IMO guidance states that a ship should be capable of transmitting ship-to-shore distress alerts by at least two separate and independent means using different radiocommunication services, subject to the applicable requirements. International Maritime Organization

SOLAS Chapter IV – Radiocommunications

SOLAS Chapter IV establishes requirements for radiocommunication services and shipborne radiocommunication equipment.

The exact equipment arrangement depends on factors including:

1. Vessel type
2. Gross tonnage
3. International voyage requirements
4. Trading area
5. GMDSS sea area
6. Flag-state requirements
7. Applicable IMO requirements
8. Recognized Organization/Class requirements
9. Equipment installation and type approval

The GMDSS framework was modernized, with amendments entering into force on 1 January 2024, allowing modern communication technologies and removing obsolete requirements. marinetechss.com

Therefore, ship managers should avoid relying solely on older equipment lists and should verify the vessel's current statutory requirements.

GMDSS Sea Areas: A1, A2, A3 and A4

The GMDSS requirements are closely connected with the sea area in which a vessel operates.

Sea Area A1

A1 is an area within the coverage of at least one VHF coast station where continuous DSC alerting is available.

VHF DSC equipment is therefore an important part of the GMDSS installation for vessels operating in A1.

Sea Area A2

A2 is an area outside A1 but within the coverage of at least one MF coast station with continuous DSC alerting capability. International Maritime Organization

Additional MF/DSC capabilities are therefore required.

Sea Area A3

A3 covers areas outside A1 and A2 that are within the coverage of a recognized mobile satellite service supported by the ship's satellite earth station.

Sea Area A4

A4 is the area outside A1, A2 and A3 and generally relates to polar regions where the applicable satellite coverage is not available.

The required radio equipment must therefore be evaluated against the vessel's actual trading area.

GMDSS Radio Equipment Requirements

The exact GMDSS equipment fit varies according to the vessel and its sea area.

The following are some of the major systems normally associated with a SOLAS GMDSS installation.

1. VHF Radio and DSC

VHF – Very High Frequency radio is one of the primary communication systems used for short-range maritime communication.

The GMDSS VHF installation includes Digital Selective Calling (DSC) capability.

Important functions include:

• Distress alerting
• Urgency communication
• Safety communication
• Ship-to-ship communication
• Ship-to-shore communication
• Bridge-to-bridge communication

IMO material identifies VHF DSC on Channel 70 and radiotelephony including Channel 16 among the applicable GMDSS arrangements. International Maritime Organization

Why VHF testing is important

During a GMDSS radio survey, the surveyor may verify:

• Transmitter performance
• Receiver performance
• DSC operation
• Channel operation
• Distress alert functionality
• Antenna condition
• Cabling
• Power supply
• Equipment programming
• Communication performance

Regular testing helps identify failures before the equipment is required during an emergency.

2. EPIRB – Emergency Position Indicating Radio Beacon

An EPIRB is a satellite-based distress alerting device used to help search-and-rescue authorities locate a vessel in an emergency.

A float-free EPIRB is part of the GMDSS equipment requirements applicable to SOLAS ships. International Maritime Organization

Depending on the installation, an EPIRB may:

• Transmit a distress alert
• Provide vessel identification
• Provide position information
• Support search-and-rescue operations
• Automatically activate when the vessel sinks, where a float-free arrangement is provided

IMO guidance notes that an EPIRB can be used as one of the independent means of distress alerting when installed appropriately or remotely activatable from the bridge. International Maritime Organization

EPIRB inspection

A professional inspection should consider:

• Physical condition
• Hydrostatic release arrangement
• Battery validity
• Expiry dates
• Identification coding
• Self-test operation
• Position information
• Mounting arrangement
• Float-free mechanism
• Operational documentation

EPIRB battery and release-unit validity should be monitored as part of the vessel's planned maintenance system.

3. SART – Search and Rescue Transponder

A Search and Rescue Transponder (SART) helps rescuers locate a survival craft or vessel during search-and-rescue operations.

SOLAS GMDSS arrangements recognize Radar SART or AIS-SART as locating devices. International Maritime Organization

The equipment can be particularly important after abandonment when the survival craft needs to be located by rescue units.

SART inspection should consider:

• Physical condition
• Battery expiry
• Self-test
• Activation
• Operational status
• Mounting/stowage
• Identification markings
• Manufacturer's service requirements

The SART should be readily accessible and maintained in accordance with applicable statutory and manufacturer requirements.

4. MF/HF Radio and DSC

For vessels operating in areas requiring medium- or high-frequency communication, MF/HF equipment forms an important part of the GMDSS installation.

MF/HF systems can provide:

• Long-range distress communication
• DSC distress alerting
• Safety communications
• Urgency communications
• General maritime communication

IMO GMDSS equipment guidance identifies MF DSC at 2187.5 kHz and HF DSC frequencies where HF equipment is required. International Maritime Organization

During an inspection, technicians may check:

• Transmitter output
• Receiver sensitivity
• DSC operation
• Distress functions
• Antenna system
• Insulators
• Earthing
• Cabling
• Power supply
• Control units
• Printer or display functions where applicable

5. NAVTEX and Maritime Safety Information

NAVTEX is used for receiving maritime safety information and navigational warnings.

Depending on the vessel's equipment arrangement and applicable requirements, GMDSS installations may include equipment capable of receiving:

• Navigational warnings
• Meteorological warnings
• Weather forecasts
• Search-and-rescue information
• Other maritime safety information

The receiver should be operational and correctly configured for the vessel's trading area.

6. Portable GMDSS VHF Equipment

Portable two-way VHF equipment is used for emergency communication, particularly in survival craft and during search-and-rescue situations.

The equipment should be:

• Readily accessible
• Properly stowed
• Operational
• Supported by valid batteries
• Maintained according to manufacturer instructions
• Available for emergency use

Battery condition is particularly important because portable equipment may be required after loss of the vessel's main electrical supply.

7. GMDSS Reserve Power and Batteries

GMDSS equipment must remain available when the vessel's main electrical supply is unavailable.

Therefore, reserve power arrangements and GMDSS batteries are important parts of GMDSS maintenance.

Inspection may include:

• Battery condition
• Capacity
• Charging system
• Connections
• Terminals
• Battery room/installation condition
• Battery expiry or replacement requirements
• Emergency power availability
• Load testing where applicable
• Records and documentation

The GMDSS installation should be evaluated as a complete system rather than treating individual radios as isolated equipment.

GMDSS Radio Survey Checklist for Ship Managers

Before arranging a GMDSS radio survey, ship managers can review the following checklist.

Equipment

• VHF operational
• VHF DSC tested
• MF/HF operational where applicable
• DSC tested
• NAVTEX operational
• EPIRB tested
• SART/AIS-SART tested
• Portable VHF radios operational
• Satellite equipment operational where applicable

Power Supply

• GMDSS batteries checked
• Battery expiry dates checked
• Charging system operational
• Emergency power available
• Battery connections checked

Installation

• Antennas inspected
• Coaxial cables checked
• Connectors checked
• Earthing checked
• Equipment securely mounted
• Bridge controls accessible

Documentation

• Radio licence available
• Safety Radio Certificate available
• Equipment certificates available
• Previous survey records available
• Maintenance records updated
• Battery records updated
• Radio log maintained

A vessel-specific checklist should always be prepared according to the vessel's statutory certificate, trading area and applicable Flag State/Class requirements.

Common GMDSS Deficiencies Found During Inspection

Some of the issues that can result in delays or deficiencies include:

1. Expired batteries

EPIRB, SART, portable VHF and GMDSS battery expiry dates should be monitored.

2. Faulty DSC

A radio may appear operational while its DSC function is not working correctly.

3. Damaged antennas or cables

Corrosion, water ingress, damaged connectors and deteriorated coaxial cables can affect radio performance.

4. Incorrect equipment programming

MMSI, call sign, vessel identification and other configuration parameters should be checked.

5. Incomplete documentation

Missing test records, certificates or maintenance records can complicate statutory inspections.

6. Poor equipment accessibility

Emergency equipment must be properly located and readily available for use.

7. Battery charging problems

A GMDSS battery that cannot maintain the required condition can compromise emergency communication capability.

GMDSS Radio Survey Service by Marinetech Safety Pvt. Ltd.

Marinetech Safety Pvt. Ltd. is an India-based marine safety equipment service and supply company supporting ship owners, ship managers, vessel operators and maritime organizations.

The company's GMDSS service covers inspection and testing of important communication and distress equipment, including:

• VHF
• VHF DSC
• MF/HF radio
• NAVTEX
• EPIRB
• SART
• GMDSS equipment
• Associated communication systems

Marinetech's published GMDSS service information also covers annual GMDSS radio surveys, certification support, calibrated testing equipment, signal analysis, defect reporting and emergency repair support. marinetechss.com

For a dedicated service page, see:

[GMDSS Radio Survey & Inspection Service in India – Marinetech Safety Pvt. Ltd.] GMDSS Radio Survey & Inspection Service

This should be your primary internal backlink from this article.

Other natural internal-link placements can use anchors such as:

• GMDSS Radio Survey Service in India
• GMDSS Radio Survey & Inspection
• Marine Radio Survey Services
• GMDSS Equipment Inspection
• GMDSS Radio Testing Services

Avoid using the exact same anchor text for every internal link.

GMDSS Services Across Indian Ports

For vessel operators, accessibility of a service provider is important because ships may have short port stays and statutory surveys can be time-sensitive.

Marinetech supports marine service requirements across major Indian maritime locations, including:

• Mumbai
• Mundra
• Surat
• Sikka
• Jamnagar
• Chennai
• Vizag
• Other Indian ports subject to service availability

The company's website also provides information about its wider marine safety service and supply portfolio. marinetechss.com

Marinetech's broader services include marine safety equipment servicing, lifesaving appliance service, firefighting appliance service, lifeboat and rescue boat service, calibration, VDR performance testing, cargo gear load testing, BWMS service and electronic/navigation communication services.

Related GMDSS & Marine Safety Articles

Readers interested in GMDSS compliance can also explore these related resources from Marinetech Safety Pvt. Ltd.:

1. What Is a GMDSS Radio Survey? Requirements, Procedure & Inspection Checklist for Ships

A detailed guide covering GMDSS survey procedures, equipment testing and inspection preparation.

What Is a GMDSS Radio Survey?

2. GMDSS Radio Survey & Inspection Service in Mumbai

A location-focused guide for ship owners and managers requiring GMDSS radio survey support in Mumbai.

GMDSS Radio Survey & Inspection Service in Mumbai

3. GMDSS Radio Survey & Inspection Service in Chennai

A guide covering GMDSS equipment inspection and radio survey requirements for vessels calling Chennai.

GMDSS Radio Survey & Inspection Service in Chennai

4. How to Prepare a Vessel for Panama Flag Survey & Inspection

Includes a section on preparing GMDSS and radio equipment before Flag State inspection.

How to Prepare a Vessel for Panama Flag Survey

5. Marine Navigation & Communication Equipment Supplier in India

Useful for ship managers looking for navigation and communication equipment supply.

Marine Navigation & Communication Equipment Supplier in India

Frequently Asked Questions – SOLAS Chapter IV GMDSS

1. What is SOLAS Chapter IV?

SOLAS Chapter IV is the Radiocommunications chapter of the International Convention for the Safety of Life at Sea. It incorporates the GMDSS framework and establishes requirements concerning shipborne radiocommunication equipment and services. International Maritime Organization

2. What GMDSS equipment is required on a ship?

The exact equipment depends on the vessel, voyage and GMDSS sea area. Common equipment includes VHF/DSC, MF/HF where applicable, satellite communication equipment, NAVTEX or other MSI reception equipment, EPIRB, SART/AIS-SART, portable GMDSS VHF radios and GMDSS reserve power.

3. What is the purpose of an EPIRB?

An EPIRB is an Emergency Position Indicating Radio Beacon used to transmit a distress alert and assist search-and-rescue authorities in locating a vessel or survival craft.

4. What is a SART used for?

A SART, or Search and Rescue Transponder, is used to assist rescuers in locating a vessel or survival craft during a search-and-rescue operation.

5. What is VHF DSC in GMDSS?

VHF DSC, or Digital Selective Calling, is a digital communication and distress-alerting function associated with the GMDSS VHF installation. Channel 70 is used for DSC, while VHF Channel 16 is used for radiotelephony distress, safety and calling functions. International Maritime Organization

6. How often should GMDSS equipment be inspected?

The required survey and maintenance schedule depends on the applicable statutory, Flag State, Class and manufacturer requirements. Ship managers should follow the vessel's Safety Radio Certificate and applicable statutory survey programme rather than relying on a generic interval.

7. What is checked during a GMDSS radio survey?

A GMDSS radio survey may include VHF/DSC, MF/HF, NAVTEX, EPIRB, SART/AIS-SART, portable VHF, satellite equipment where applicable, batteries, antennas, power supplies, documentation, equipment identification and maintenance records.

8. Where can I get GMDSS Radio Survey services in India?

Marinetech Safety Pvt. Ltd. provides GMDSS Radio Survey & Inspection Services in India, including inspection and testing of VHF, MF/HF, NAVTEX, EPIRB, SART and other applicable GMDSS equipment. marinetechss.com

Conclusion

GMDSS is an essential component of modern maritime safety communication. Compliance with SOLAS Chapter IV requires ship owners and managers to ensure that the vessel's applicable radio equipment remains operational, properly maintained and supported by appropriate documentation.

VHF/DSC, MF/HF, EPIRB, SART, NAVTEX, portable VHF equipment, satellite communication systems and GMDSS reserve power all have important roles within the overall emergency communication arrangement.

Regular inspection and professional testing can help identify equipment problems before they become critical during an emergency or statutory survey.

For professional GMDSS Radio Survey & Inspection Services in India, ship owners and managers can contact Marinetech Safety Pvt. Ltd.

Request GMDSS Radio Survey Service from Marinetech Safety Pvt. Ltd.

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