Introduction: Making Contact on the Open Ocean
Picture the scene: two ships meeting on the vast expanse of the ocean. For safety, coordination, or simple passage planning, they need to communicate. But how do they do it? If you’re on one vessel, how do you initiate a conversation with another when you don’t know their call sign or what radio frequency they monitor?
This is a fundamental question in marine radio communication. The answer lies in a well-established global system that combines traditional procedures with modern technology, ensuring that vessels can indeed talk to each other reliably and efficiently. This article will explain the primary methods used to make that crucial first contact.
—-The Foundation of Maritime Communication: The VHF Marine Radio—-
The primary tool for short-to-medium range (typically up to 20-30 nautical miles) communication at sea is the VHF marine radio. The use of these radios is governed by international agreements, ensuring that mariners worldwide have a common platform for communication. The key to contacting an unknown vessel lies in knowing which channels to use and what technologies are available to you.
There are two principal methods for establishing contact: the traditional voice hail and the modern digital call.
Method 1: The Traditional Hail on VHF Channel 16
For decades, the cornerstone of ship-to-ship contact has been VHF Channel 16.
What is Channel 16? Think of Channel 16 as the “town square” or the emergency hailing channel of the seas. Under the Global Maritime Distress and Safety System (GMDSS), most commercial vessels, and by good practice, most recreational boats, are required to maintain a listening watch on this channel. Its primary purposes are for distress, urgency, and safety calls, but it is also used for making initial contact with another station.
The Procedure for Hailing an Unknown Vessel:
If you see another vessel and need to speak with them, you can use Channel 16 to make a voice call.
Identify the Target Vessel: You must describe the vessel you are trying to reach as clearly as possible. This can be by its name (if you can read it), its vessel type, and its position relative to you.
Example: “Motor vessel, white hull, with the name ‘Sea Serpent’ on the stern, approximately three miles off my starboard bow…”
State Your Vessel’s Name: Clearly identify your own vessel.
Make the Call: The standard format is to repeat the other vessel’s name/description three times, followed by your vessel’s name three times.
Example Call: “Sea Serpent, Sea Serpent, Sea Serpent, this is motor vessel Blue Dolphin, Blue Dolphin, Blue Dolphin, on VHF Channel One-Six. Over.”
Listen and Switch Channels: After they respond, you must immediately suggest moving to a non-distress, working channel to continue the conversation. These are ship-to-ship channels like 06, 08, 69, or 72.
Example Response: “Blue Dolphin, this is Sea Serpent, roger. Switch to channel six-niner. Over.” Both vessels then immediately change to the agreed-upon channel.
Limitations: While effective, this method clutters the international distress channel with calling traffic. It also relies on a clear visual description and the other vessel actively listening and recognizing your call.
Method 2: The Modern, Efficient Solution – AIS and DSC
Today, there is a much more precise and preferred method that leverages modern technology: the combination of the Automatic Identification System (AIS) and Digital Selective Calling (DSC).
Step 1: Identify the Vessel with AIS
What is AIS? The Automatic Identification System is a game-changer for marine communication. AIS transponders on vessels automatically broadcast information—including the vessel’s name, call sign, position, course, speed, and most importantly, its MMSI (Maritime Mobile Service Identity) number—to all other AIS-equipped vessels in the vicinity.
How it Works: On your chartplotter, radar, or modern VHF radio display, you will see other vessels appear as AIS targets. By selecting a target, you can immediately access all its identifying information without needing binoculars.
Step 2: Initiate a Direct Call with DSC
What is DSC? Digital Selective Calling is a feature built into all modern fixed-mount VHF radios. It works like a direct-dialing system for ships, using the unique 9-digit MMSI number as a “phone number.” All DSC calls are made on the dedicated data channel, VHF Channel 70, keeping Channel 16 clear.
The Procedure for an AIS/DSC Call:
Select the AIS Target: On your chartplotter or radio screen, select the AIS target of the vessel you wish to call.
Initiate DSC Call: Choose the option to “Call with DSC,” “Make a DSC Call,” or similar.
Propose a Working Channel: The system will automatically use the vessel’s MMSI from the AIS data. You simply need to select the type of call (e.g., “Routine”) and propose a voice channel for your conversation (e.g., Channel 69).
Send the Digital Call: Press the “call” or “send” button.
A silent, digital call is sent directly to that specific vessel. Their DSC radio will ring with an alert, displaying your vessel’s name and the channel you proposed. They simply press a button to accept, and both radios automatically switch to the agreed-upon channel for a private voice conversation.
Advantages of the AIS/DSC Method:
Silent and Unambiguous: It directly targets one vessel without broadcasting to everyone on Channel 16.
Efficient: It’s fast, simple, and requires no lengthy voice descriptions.
Keeps Channel 16 Clear: It follows best practices by reserving the distress channel for its intended purpose.
Conclusion: The Right Way to Communicate at Sea
So, can ships communicate at sea if they don’t know each other? Absolutely. The system is designed for precisely this scenario.
While the traditional voice hail on VHF Channel 16 remains a valid option, the modern and preferred method is to use the Automatic Identification System (AIS) to identify a nearby vessel and obtain its MMSI number, and then use Digital Selective Calling (DSC) to place a direct, silent call. This powerful combination of technologies makes modern radio communication between vessels safer, clearer, and more efficient than ever before. Understanding and using these tools correctly is a hallmark of good seamanship in the 21st century.
