2.4 Specific VHF Channel Allocations (Ch 16, 70, 06, 13, 67, 80)

2.4 Specific VHF Channel Allocations (Ch 16, 70, 06, 13, 67, 80)

To prevent chaos across the radio spectrum, the International Telecommunication Union (ITU) and national radio authorities (such as Ofcom in the UK) enforce strict channel allocations. Specific channels are legally reserved for distress alerting, search and rescue, bridge-to-bridge navigation safety, routine digital alerting, and port operations. Using a reserved channel for an unauthorized purpose is a breach of international law and can carry heavy civil and criminal penalties.

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1. Master Summary of Mandatory Exam Channels

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2. In-Depth Operational Breakdown

Channel 16: Voice Distress, Safety, & Calling (156.800 MHz)

Channel 16 is the single most important voice frequency in the maritime mobile service. It is monitored continuously by coastguard rescue coordination centers (RCCs) and all vessels at sea.

• Permitted Uses:
  1. Distress Traffic: Mayday calls and distress messages.
  2. Urgency Traffic: Pan-Pan calls regarding vessel or personnel safety.
  3. Safety Traffic: Securite navigational and gale warnings.
  4. Initial Calling: Contacting another vessel or coast station when DSC is unavailable.
• Strict Calling Restrictions: Voice calling on Channel 16 for non-distress purposes must be kept as brief as possible. The calling vessel must not exceed 1 minute when establishing initial contact, and must immediately request the called station to change to an appropriate inter-ship working channel (e.g., Channel 72 or 77).
• Prohibited Uses: Chit-chat, radio checks, harbor enquiries, and prolonged conversations are strictly illegal on Channel 16.

Channel 70: Dedicated Digital Selective Calling (156.525 MHz)

Channel 70 is the sole GMDSS digital signaling channel in the VHF band.

• Zero Voice Rule: Transmitting voice audio on Channel 70 is physically blocked by compliant GMDSS radios and is strictly prohibited by ITU regulations. Voice transmissions corrupt digital data bursts, potentially blocking automated Mayday alerts.
• Automated Data Traffic: Used exclusively by internal radio modems to transmit and receive 100-baud phase-shift keyed digital messages (distress alerts, routine individual calls, group calls, and geographic area calls).

Channel 06: Primary Inter-Ship Safety (156.300 MHz)

Channel 06 is allocated internationally for safety communications between ship stations.

• SAR Operations: During a maritime search and rescue operation, participating vessels, lifeboats, and SAR helicopters/aircraft use Channel 06 to coordinate search grids and rescue maneuvers.
• Inter-Ship Safety: Can also be used for critical safety communications between vessels at sea when Channel 13 is congested.

Channel 13: Bridge-to-Bridge Navigation Safety (156.650 MHz)

Channel 13 is designated globally under the Convention on the International Regulations for Preventing Collisions at Sea (COLREGs) for bridge-to-bridge communications.

• Collision Avoidance: Ships, commercial tugs, ferries, and recreational vessels use Channel 13 to communicate intentions when navigating narrow channels, traffic separation schemes (TSS), or meeting head-on.
• 1 Watt Power Rule: Radio operators should maintain their transceivers on 1 Watt low power when using Channel 13 to avoid overwhelming bridge-to-bridge communications in nearby harbors or waterways.

Channel 67: UK Small Craft Safety & Coastguard (156.375 MHz)

Channel 67 is a specialized channel allocation in the United Kingdom.

• Small Craft Safety: Designated by HM Coastguard as the secondary safety and small craft working channel.
• Coastguard Maritime Safety Information (MSI): HM Coastguard announces weather bulletins and gale warnings on Channel 16, then broadcasts the full bulletin on Channel 67 (or regional working channels).

Channel 80: UK Marina Port Operations (Duplex 156.025 / 160.625 MHz)

Channel 80 is the standard duplex channel used across the UK for marina communications.

• Marina Services: Yacht skippers use Channel 80 to request pontoon berth assignments, water taxi shuttles, fuel pontoon clearance, and lock entry from marina staff.
• Duplex Architecture: Because Channel 80 is duplex, skippers must remember that two yachts sitting in the same marina cannot talk to each other on Channel 80; it is strictly a ship-to-marina channel.