MFHF
MF/HF (Medium Frequency / High Frequency) radio is a SOLAS-mandated marine communication system forming part of the Global Maritime Distress and Safety System (GMDSS).
It enables ships to transmit and receive distress, urgency, safety, and routine communications over long ranges, including areas beyond VHF coverage, using DSC (Digital Selective Calling) and radiotelephony/NBDP.
Is MF/HF mandatory under SOLAS?
Yes. MF/HF is mandatory under SOLAS Chapter IV for ships operating in Sea Areas A3 and A4, as part of GMDSS.
Which vessels are required to carry MF/HF?
Passenger ships
Cargo ships of 300 GT and above on international voyages
Operating in Sea Area A3 and/or A4.
What is the main purpose of MF/HF radio?
MF/HF provides long-range distress alerting and communications when vessels are outside VHF and MF coastal coverage.
What distress alerting method is used in MF/HF?
MF/HF uses Digital Selective Calling (DSC) for automated distress alerts, followed by voice or NBDP communication.
What frequencies are used in MF/HF?
MF band: around 2187.5 kHz (DSC)
HF bands: multiple DSC and radiotelephony frequencies between 4–27 MHz
Is MF/HF part of GMDSS?
Yes. MF/HF is a core GMDSS component for vessels navigating in ocean and polar regions.
Does MF/HF require continuous watch?
Yes. A continuous DSC watch must be maintained on 2187.5 kHz and HF DSC frequencies, either by the radio or an integrated system.
Can MF/HF be used for routine communications?
Yes. In addition to distress and safety, MF/HF supports routine ship-to-ship and ship-to-shore communications.
Is testing and maintenance of MF/HF required?
Yes. MF/HF equipment must be regularly tested, logged, and maintained, with antenna and power supply checks as required by SOLAS.
Is MF/HF inspected during surveys?
Yes. Flag and Port State inspectors verify DSC operation, distress functionality, antenna condition, reserve power, and radio logs.
Conclusion
MF/HF radio is a critical SOLAS-mandated GMDSS communication system that ensures long-range distress alerting and safety communications when vessels operate beyond coastal coverage. By enabling reliable contact with shore stations and other ships in Sea Areas A3 and A4, MF/HF plays a vital role in maritime safety, emergency response, and regulatory compliance.
Keeping MF/HF equipment fully operational, properly tested, and correctly logged is essential to meet IMO requirements and successfully pass flag and port State inspections.