Marine VHF Radio Channels Explained
A practical guide to VHF marine radio channel assignments — what each channel is for, which ones you must monitor, and how to use them correctly.
Why Channel Assignments Matter
VHF marine radio operates on internationally standardized channels. Using the wrong channel — even accidentally — can interfere with distress communications, Coast Guard operations, or other vessels. Understanding the channel system is fundamental to safe and legal marine radio operation.
The Most Important Channels
Channel 16 — Distress, Safety, and Calling
Channel 16 (156.800 MHz) is the single most important VHF marine channel. It is the international distress, safety, and calling frequency.
All vessels equipped with VHF radio must monitor Channel 16 at all times while underway. When you need to call another vessel or marina, you make initial contact on Channel 16 — then both parties agree to move to a working channel for the actual conversation.
Never use Channel 16 for routine communications beyond the initial call. Keep it clear for distress calls.
Channel 70 — DSC Only
Channel 70 (156.525 MHz) is reserved exclusively for Digital Selective Calling (DSC). No voice communications are permitted on this channel under any circumstances.
DSC is an automated digital system that sends formatted distress alerts containing your vessel identity and GPS position. Modern VHF radios with DSC capability monitor Channel 70 automatically in the background while you use other channels.
Channel 13 — Bridge-to-Bridge Navigation
Channel 13 (156.650 MHz) is the navigation safety channel used for vessel-to-vessel communications regarding the safe passage of ships. Power is limited to 1 watt on Channel 13 in most circumstances.
If you are approaching a bridge, entering a harbor, or need to coordinate a passing arrangement with another vessel, Channel 13 is the correct channel. Commercial vessels are required to monitor it in many US waterways.
Channel 22A — Coast Guard Liaison
Channel 22A (157.100 MHz) is used for communications with the US Coast Guard after initial contact on Channel 16. When the Coast Guard responds to your call on 16, they will typically ask you to switch to 22A for the working conversation.
Working Channels
Once initial contact is made on Channel 16, move to one of these working channels:
Channel 06 (156.300 MHz) — Intership safety communications. Also used for search and rescue coordination between vessels and aircraft.
Channel 09 (156.450 MHz) — Boater calling channel. A recreational alternative to Channel 16 for non-distress calling. Many marinas and yacht clubs monitor Channel 09.
Channel 12 (156.600 MHz) — Port operations. Used in and around ports and harbors for vessel traffic communications.
Channel 72 (156.625 MHz) — Non-commercial intership only. Popular among recreational boaters for vessel-to-vessel conversation.
Channel 78A (156.925 MHz) — Non-commercial working channel widely used by recreational boaters.
Public Correspondence Channels
Channels 24, 25, 26, 27, and 28 are public correspondence channels used to place telephone calls through marine telephone operators. These duplex channels — the ship and shore station transmit on different frequencies — connect to the land telephone network.
Weather Channels
WX-1 through WX-7 are receive-only channels for NOAA Weather Radio continuous weather broadcasts. These are not two-way channels — you can listen but not transmit. Always check the weather forecast before departing and monitor weather channels when conditions are uncertain.
The INT/USA Switch
Many VHF radios have an INT/USA switch. This setting changes certain channel assignments to US-specific designations (such as Channel 22A) versus international equivalents. Make sure your radio is set to USA when operating in US waters.
Proper Channel Usage Summary
| Channel | Use | |---------|-----| | 16 | Distress, safety, initial calling — monitor always | | 70 | DSC digital only — no voice | | 13 | Bridge-to-bridge navigation — 1 watt | | 22A | US Coast Guard liaison | | 06 | Intership safety and SAR | | 09 | Boater calling (recreational) | | 12 | Port operations | | 72 | Non-commercial intership | | WX | Weather receive only |
Learn More
Understanding VHF channel assignments is a core part of the FCC Marine Radio Operator Permit (MROP) exam. Hangar Academy's MROP course covers channel assignments, operating procedures, distress communications, and everything else you need to pass the exam and operate marine radio correctly.