Most people carry a mobile phone whenever they go boating. It seems reasonable to assume that, if something goes wrong, a phone call will be enough to get help.
Sometimes it will.
But marine communication works differently from ordinary telephone communication, and a VHF radio provides capabilities that a mobile phone does not always offer.
A marine VHF can allow vessels to communicate directly, receive relevant maritime information and contact rescue services through established marine procedures. In an emergency, it can also make a call that other nearby vessels may hear.
For RIB owners, understanding VHF is less about learning another piece of technology and more about knowing how to communicate effectively on the water.
What is marine VHF?
Marine VHF is a radio communication system used by vessels and maritime services.
It operates on designated marine channels, with different channels and procedures assigned to different purposes.
Depending on the region, these may include distress and calling, vessel-to-vessel communication, port operations and other maritime services.
Unlike a normal phone call, a radio transmission may be heard by multiple stations monitoring the same channel within radio range.
This shared communication capability can be particularly important when vessels need to coordinate or respond to an emergency.
Why not simply use a mobile phone?
A mobile phone is useful aboard and can be an important additional communication tool.
However, its operation depends on available network coverage or other supported connectivity.
Coverage can become unreliable offshore or in areas with challenging geography.
A telephone call also normally reaches a specific recipient rather than alerting other vessels nearby.
Marine VHF has different limitations, but it provides direct radio communication and established maritime calling procedures.
The two systems are complementary rather than interchangeable.
Fixed VHF or handheld radio?
A fixed VHF is usually installed at the helm and connected to an external antenna.
Its performance depends on the radio, antenna installation, available power and surrounding conditions.
A handheld VHF offers portability and may be useful on smaller RIBs or as a backup.
However, handheld radios generally have more limited antenna height and power arrangements, which can affect practical range.
Water resistance, battery life and charging arrangements should be considered.
For longer coastal journeys, a properly installed fixed radio may offer significant advantages, while a handheld unit can provide useful additional flexibility.
Understanding VHF range
Marine VHF communication is largely influenced by line-of-sight conditions.
Antenna height, surrounding terrain, obstructions and radio installation all affect the distance over which communication is possible.
There is no single guaranteed range that applies to every RIB.
A fixed radio with a suitable antenna may communicate farther than a handheld under comparable conditions, but actual performance varies.
It is important not to assume that a VHF transmission will always reach a distant shore station.
What is DSC?
Digital Selective Calling, or DSC, allows suitably equipped radios to send digital calls using designated procedures.
A correctly configured DSC distress function can transmit a digital distress alert, potentially including the vessel’s identity and position when suitable position data is available.
However, DSC functionality depends on correct configuration, registration or identity arrangements and appropriate installation.
The operator must understand how the system works and what procedures follow an alert.
A distress button is not a substitute for training.
What is an MMSI?
An MMSI, or Maritime Mobile Service Identity, is a numerical identity used in relevant maritime radio systems.
It is associated with a vessel or station according to applicable arrangements.
Requirements for obtaining and programming an MMSI vary by jurisdiction.
Owners should use the appropriate national authority or authorised process rather than entering an arbitrary number.
Incorrect programming can create problems, particularly because some radios restrict how often an MMSI can be changed.
Emergency communication
Marine radio procedures distinguish between different types of urgent communication.
A distress call is used when a vessel or person faces grave and imminent danger and requires immediate assistance.
Other established procedures cover urgent situations that do not meet the same distress criteria and safety-related information.
Operators should learn the relevant calls and procedures through recognised training.
It is also important to understand that the ability to transmit a call does not guarantee that it will be received.
For more remote passages, additional emergency communication equipment may be appropriate.
Licensing and operating requirements
Marine radio licensing requirements differ between countries.
Depending on the jurisdiction and installation, the vessel may require a radio licence and the operator may need an appropriate certificate.
Channel usage and procedures can also vary by region.
Before installing or operating VHF equipment, check the requirements of the relevant national authority.
This is especially important for owners who travel between countries.
A VHF is only useful if you know how to use it
A radio installed at the helm can provide reassurance, but it is much more valuable when the operator is familiar with it.
Learn how to select channels, adjust volume and squelch, make routine calls and follow the applicable emergency procedures.
Check the equipment according to appropriate guidance without making unnecessary or improper distress transmissions.
If the radio supports DSC, confirm that its configuration and position information are correct.
A little practice makes a considerable difference.
Communication is part of seamanship
A marine VHF isn’t simply another electronic accessory.
It is a tool for communicating with the maritime world around you.
For a RIB used regularly on coastal journeys, it can provide valuable capability that a smartphone alone may not offer.
Choose an appropriate radio, install it correctly, follow local requirements and learn the procedures.
The best time to understand your VHF is long before you need to use it in an emergency.