VHF Channel Usage Flashcards

What is the transmission power for most ship-to-shore communications?

Answer: High power (25 watts) for long range communications

High power (25 watts) should be used for ship-to-shore communications to ensure reliable contact. Low power (1 watt) is used for short-range communications to reduce interference with distant stations.

What is the typical VHF radio range at sea?

Answer: 20-30 miles depending on antenna height

VHF radio has line-of-sight range typically 20-30 miles between vessels and up to 40 miles to shore stations on high ground. Antenna height significantly affects range as VHF cannot propagate beyond the horizon.

Which power setting should be used for close-range marina communications?

Answer: Low power (1 watt)

Low power (1 watt) should be used for short-range communications such as marina approaches to reduce interference with other stations using the same channel at greater distances.

What is a 'working channel' in VHF radio procedure?

Answer: Any channel other than Channel 16 used for the main body of communication

A working channel is any agreed VHF channel (other than the calling/distress channels) on which the substantive communication takes place after initial contact has been made on Channel 16 or via DSC.

Can Channel 16 be used for routine ship-to-ship conversation?

Answer: No, it must only be used for distress, safety, calling, and essential navigation

Channel 16 must not be used for routine conversation. Its sole purpose is distress and safety traffic, calling (to establish contact), and essential navigational communications. All other traffic must move to a working channel.

What channel do UK Coast Guard stations primarily broadcast Maritime Safety Information on?

Answer: Channel 16 announcement then Channel 67 or 62 for the broadcast

HM Coastguard announces Maritime Safety Information (MSI) broadcasts on Channel 16 and instructs vessels to switch to Channel 67 (or sometimes 62) for the actual broadcast to keep Channel 16 free.