100+ Free SAMSA GMDSS ROC Practice Questions

Prepare for the SAMSA STCW Section A-IV/2 GMDSS Restricted Operator Certificate exam with instant access — no signup required.

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2026 Statistics

Key Facts: SAMSA GMDSS ROC Exam

100

Exam Questions

SAMSA STCW A-IV/2

2 hours

Exam Duration

SAMSA Examination Rules

70%

Passing Mark

SAMSA Standards

Sea Area A1

Operational Zone

VHF Range (~20-30 NM)

406 MHz

EPIRB Frequency

COSPAS-SARSAT

9 GHz

SART Radar Frequency

X-Band Marine Radar

The SAMSA STCW GMDSS ROC exam consists of 100 questions evaluated over a 2-hour duration. Note: Our 100 MCQs are an English-language MCQ study adaptation for SAMSA radio examinations covering VHF radiotelephony, DSC, EPIRB, SART, emergency protocols, logkeeping, and battery maintenance.

Sample SAMSA GMDSS ROC Practice Questions

Try these sample questions to test your SAMSA GMDSS ROC exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1What is the primary international radiotelephony channel for distress, safety, and calling in the marine VHF band?

A.VHF Channel 16

B.VHF Channel 13

C.VHF Channel 70

D.VHF Channel 06

Explanation: VHF Channel 16 (156.8 MHz) is the international radiotelephony channel for distress calls, urgency signals, safety announcements, and initial calling between vessels or coast stations. Vessels monitored under GMDSS must maintain a continuous listening watch on Channel 16 when at sea. Once contact is established, stations must shift to a designated working channel.

2Which VHF channel is reserved strictly for Digital Selective Calling (DSC) and prohibits any voice radiotelephony transmissions?

A.VHF Channel 16

B.VHF Channel 70

C.VHF Channel 67

D.VHF Channel 12

Explanation: VHF Channel 70 (156.525 MHz) is designated internationally exclusively for Digital Selective Calling (DSC) distress alerts, urgency, safety, and routine calls. Voice transmissions are strictly prohibited on Channel 70 to ensure data signals remain free from interference. Modern GMDSS VHF installations feature a dedicated receiver permanently tuned to Channel 70.

3Under GMDSS definitions, how is Sea Area A1 defined?

A.An area within the coverage of an Inmarsat geostationary satellite providing continuous alerting

B.An area excluding Sea Area A1 within the coverage of at least one MF coast station providing continuous DSC alerting

C.An area within the radiotelephone coverage of at least one VHF coast station in which continuous DSC alerting is available

D.An ocean region outside Sea Areas A1, A2, and A3 covering polar waters above 70 degrees latitude

Explanation: Sea Area A1 is defined under SOLAS and STCW regulations as an area within the radiotelephone coverage of at least one VHF coast station equipped with continuous Digital Selective Calling (DSC) alerting facilities. Depending on antenna height and topography, Sea Area A1 typically extends 20 to 30 nautical miles from shore. The GMDSS Restricted Operator Certificate (ROC) qualifies seafarers to operate radios exclusively within Sea Area A1.

4What is the primary international purpose of VHF Channel 13?

A.Port operations and tug assistance

B.Search and rescue aircraft-to-ship communications

C.Public correspondence and marine telephone calls

D.Bridge-to-bridge safety of navigation communications

Explanation: VHF Channel 13 (156.650 MHz) is the designated international channel for bridge-to-bridge communications concerning the safety of navigation. Navigating officers use Channel 13 to exchange collision-avoidance intentions, passing agreements, and maneuvering signals directly between ships. Power output on Channel 13 is often limited to 1 watt to minimize distant interference.

5What power setting should be selected on a marine VHF transceiver when operating in close proximity to other vessels in a harbor?

A.Low power (1 Watt)

B.High power (25 Watts)

C.Medium power (10 Watts)

D.Maximum emergency power (50 Watts)

Explanation: Marine VHF radios are required by ITU and SAMSA regulations to feature a low-power setting of 1 Watt. Operators must select low power (1W) for harbor operations and short-range communications to avoid causing unnecessary radio interference to distant stations sharing the same channel. High power (25W) is reserved for long-range coastal communications.

6What is meant by 'simplex' operation on a marine VHF channel?

A.Both stations can transmit and receive simultaneously on two separate frequencies

B.Both stations transmit and receive on the same single frequency, allowing only one station to speak at a time

C.Communications occur in one direction only, with no receiving capability

D.Signals are automatically relayed through a satellite ground station

Explanation: Simplex channels use a single frequency for both transmission and reception. Operators must press the Push-to-Talk (PTT) switch to speak and release it to listen, meaning only one station can transmit at any given instant. Examples of simplex channels include VHF Channels 06, 13, and 16.

7What is a Maritime Mobile Service Identity (MMSI)?

A.A 5-character alphanumeric radio call sign assigned by SAMSA

B.A 6-digit serial number embedded inside a radar transponder

C.A 9-digit unique numerical identification code assigned to a ship, coast station, or group of stations

D.A 12-character satellite tracking code used by Inmarsat

Explanation: An MMSI is a unique 9-digit number transmitted automatically by Digital Selective Calling (DSC) equipment and Automatic Identification Systems (AIS) to identify the calling station. The first three digits represent the Maritime Identification Digits (MID), indicating the vessel's flag state or country of registration.

8What are the Maritime Identification Digits (MID) assigned to South Africa in MMSI numbers?

A.503

B.235

C.366

D.601

Explanation: South Africa's primary Maritime Identification Digits (MID) assigned by the International Telecommunication Union (ITU) is 601. All South African registered vessel MMSI numbers begin with 601 followed by 6 individual digits (e.g., 601XXXXXX).

9What is the primary operational application of VHF Channel 06?

A.Inter-ship safety communications and Search and Rescue (SAR) coordination

B.Coast station public correspondence

C.Port operations and pilotage requests

D.Continuous marine weather broadcasts

Explanation: VHF Channel 06 (156.300 MHz) is internationally reserved for inter-ship communications concerning safety of navigation, as well as operational communications between rescue ships and SAR aircraft during search and rescue missions.

10What distinguishes a duplex VHF channel from a simplex VHF channel?

A.Duplex channels use digital modulation, while simplex channels use analog voice

B.Duplex channels transmit and receive on two separate frequencies spaced apart, allowing simultaneous two-way conversation

C.Duplex channels require high power (25W), whereas simplex channels are limited to 1W

D.Duplex channels are used exclusively for satellite relays

Explanation: Duplex channels utilize two distinct frequencies: one frequency for transmitting and another frequency for receiving (typically spaced 4.6 MHz apart in the marine VHF band). With appropriate hardware (duplexer filter or dual antennas), stations can talk and listen simultaneously, similar to a telephone.

About the SAMSA GMDSS ROC Exam

The SAMSA STCW GMDSS Restricted Operator Certificate (ROC) validates competency in operating marine VHF radio equipment equipped with Digital Selective Calling (DSC), 406 MHz EPIRBs, Radar SARTs, and distress communication protocols within GMDSS Sea Area A1 (coastal VHF range up to ~30 nautical miles).

Assessment

100 multiple-choice questions

Time Limit

2 hours

Passing Score

70%

Exam Fee

R 1,250 (South African Maritime Safety Authority (SAMSA))

SAMSA GMDSS ROC Exam Content Outline

35%

VHF Radiotelephony & DSC in Sea Area A1

VHF operating channels, channel 16/70 duties, simplex vs duplex channels, MMSI structure, DSC priority calls, and Sea Area A1 boundaries.

25%

Emergency Beacons (406 MHz EPIRB, SART)

COSPAS-SARSAT satellite system, 406 MHz EPIRBs, Hydrostatic Release Units (HRU), 9 GHz Radar SART search arcs, AIS-SARTs, and maintenance schedules.

20%

Distress, Urgency & Safety Communication Protocols

MAYDAY call structure, MAYDAY RELAY procedures, PAN PAN urgency signals, SECURITE navigational warnings, radio silence control (SEELONCE MAYDAY), and false distress alert cancellation.

20%

Radio Logkeeping & Battery Maintenance

Official GMDSS radio log entries, compulsory listening watches, reserve power supply standards, lead-acid vs gel batteries, specific gravity measurements, and emergency testing routines.

How to Pass the SAMSA GMDSS ROC Exam

What You Need to Know

Passing score: 70%
Assessment: 100 multiple-choice questions
Time limit: 2 hours
Exam fee: R 1,250

Keys to Passing

Work through all 100 available questions
Review every answer and explanation
Track weak areas and revisit them
Use our AI tutor for tough concepts

SAMSA GMDSS ROC Study Tips from Top Performers

1Memorize the standard MAYDAY radiotelephony format: MAYDAY (x3), vessel name/callsign (x3), position, nature of distress, assistance required, number of persons on board.

2Understand VHF channel allocations: Channel 16 for radiotelephony distress/safety, Channel 70 exclusively for DSC, Channel 13 for bridge-to-bridge safety of navigation.

3Learn the operation of 406 MHz EPIRBs, including how the Hydrostatic Release Unit (HRU) automatically deploys the beacon at depths between 1.5 to 4 meters.

4Master Radar SART principles: operating on 9 GHz (X-band radar), creating 12 blips on an observing radar screen that elongate into concentric arcs as the rescue vessel approaches.

5Review lead-acid marine battery maintenance: measuring specific gravity with a hydrometer (1.280 for fully charged), topping up with distilled water, and checking reserve power capacity.

6Know the procedure for cancelling accidental DSC distress alerts: immediately switch off/on, select VHF Ch 16, and broadcast an explicit cancellation message to all stations.

Frequently Asked Questions

What is the SAMSA GMDSS Restricted Operator Certificate (ROC)?

The SAMSA GMDSS ROC is a South African maritime radio qualification issued under STCW Section A-IV/2. It authorizes seafarers and vessel masters to operate GMDSS radio equipment on vessels operating exclusively within GMDSS Sea Area A1 (VHF range of coast stations, typically up to 20-30 nautical miles offshore).

What is the difference between GMDSS ROC and GMDSS GOC?

The Restricted Operator Certificate (ROC) is limited to GMDSS Sea Area A1 using VHF radiotelephony and DSC equipment. The General Operator Certificate (GOC) covers all Sea Areas (A1, A2, A3, and A4) and includes MF/HF single sideband radios, Inmarsat satellite terminals, and NAVTEX communications.

How many questions are on the SAMSA GMDSS ROC exam and what is the passing score?

The examination comprises 100 multiple-choice questions with a time limit of 2 hours. Candidates must achieve a minimum score of 70% to pass.

Are these practice questions officially endorsed by SAMSA?

No. Our 100 MCQs are an independent English-language MCQ study adaptation designed to help candidates prepare for SAMSA radio examinations by testing required STCW Section A-IV/2 competencies.

What equipment does a GMDSS ROC holder operate?

An ROC holder is certified to operate VHF radiotelephones, VHF Digital Selective Calling (DSC) controllers (Ch 70), 406 MHz EPIRBs, 9 GHz Search and Rescue Transponders (SART), AIS-SARTs, and portable hand-held VHF radios for survival craft.

How long is the SAMSA GMDSS ROC certificate valid?

Under STCW requirements, the GMDSS ROC is valid for 5 years and must be revalidated by demonstrating continuous professional sea service or completing an approved refresher course.