VHF and DSC transceivers
What is being checked
The inspector is checking whether bridge VHF and DSC equipment supports distress, safety and navigational communication without replacing visual and radar collision assessment, with officers able to configure, cross-check, test and respond to failure of the actual equipment fitted.
Ready onboard
0/6 completePractice questions
Answer aloud, then open the preparation point.
1What safety function does vhf and dsc transceivers provide?
Bridge vhf and dsc equipment supports distress, safety and navigational communication without replacing visual and radar collision assessment.
2How is the complete function tested?
Use built-in DSC test facilities, approved test calls and radio checks, verify both main and reserve supply and confirm audio, control and antenna condition.
3What is its principal limitation?
VHF range and clarity are limited by line of sight, interference, antenna condition, wrong power and language; an agreed radio manoeuvre can still conflict with COLREG.
4What is your response if it fails?
Use alternate VHF or GMDSS equipment, apply sound and visual signals, navigate conservatively and report and repair the defect.
5Show the latest test and operational evidence.
Link the dated record to the actual unit, test method, result, defect response and restoration; a panel lamp test alone is not sufficient where the full signal path can be tested.
Where an observation may arise
The responsible officer cannot explain safe use, limitations or failure response.
Testing does not prove the required operational function or remote indication.
DSC position or time is absent, stale or wrong.
High power is used unnecessarily during close operations or in hazardous-area contexts.
VHF conversation is treated as overriding COLREG responsibility.
Past observations for practice
OP was not aware that reliance on VHF should be avoided during the collision avoidance situations.
Master's practical note
Review one recent bridge-to-bridge exchange. Clear words do not make an unsafe or ambiguous manoeuvring agreement compliant with the collision regulations.
Equipment boundary and references
Equipment boundary: Radio equipment and watchkeeping depend on the ship's GMDSS sea areas and approved station. Portable sets used in hazardous areas require appropriate intrinsic-safety certification.
References
- OCIMF SIRE 2.0 Question Library Part 1, Version 1.0, Question 4.1.13
- SOLAS Chapter IV
- COLREG
- IMO Standard Marine Communication Phrases
- ITU Radio Regulations
Last reviewed: 2026-09-11