VHF Radio Basics

A marine VHF Radio is a shared safety channel system. Before transmitting, listen first. If another station is using the channel, wait unless you have distress traffic.

Press-to-talk means only one station can speak at once. Think, press, speak clearly, release, and listen.

High power increases range but can create unnecessary congestion. Low power is usually enough for close routine traffic such as marina or nearby vessel calls.

Squelch suppresses background noise. Too much squelch can hide weak signals; too little can make the set noisy and tiring to monitor.

VHF range is largely line-of-sight. A masthead antenna normally reaches further than a handheld at cockpit height.

Range also depends on power, antenna condition, obstructions, weather, and the height of the receiving station.

Before a real call, know how to power the set, change channel, adjust volume, set squelch, select high or low power, and use the push-to-talk button. In stress, a hidden menu can cost time.

A good helm briefing includes the radio basics: which channel is being monitored, how to transmit, where the vessel identity card is, and who is authorised to speak if the skipper is busy.

Squelch set too low leaves constant noise; squelch set too high can hide weak calls. Set it just above the background noise threshold, then keep the volume loud enough to hear a call in the cockpit.

A listening watch is active seamanship. It helps you hear distress, urgency, safety broadcasts, traffic movements, and instructions from coastguard, harbour, or other vessels.

Marine VHF is largely line-of-sight. A masthead aerial usually gives better range than a handheld at cockpit level, while cliffs, harbour walls, and buildings can reduce coverage.

Use low power first for nearby routine calls. Use high power when range or priority requires it, especially distress or urgency traffic where the aim is to be heard clearly by the right stations.

Before pressing PTT, check the channel, power, volume, squelch, message priority, and essential information. A five-second pause often prevents a messy transmission.

If no one answers, do not simply transmit louder and longer. Check the set-up, listen, repeat correctly, or escalate according to priority and risk.

Power the set, select the correct channel, raise volume to a useful level, then open squelch until noise is heard and close it only until the noise just disappears. Over-tight squelch can hide a weak but important call. Use the display dimmer without making safety information unreadable.

Dual watch monitors Channel 16 alongside another selected channel; scan checks a programmed list. They are listening aids, not permission to ignore the required watch or transmit on whichever channel happens to stop the scan. Stop and identify the received channel before replying.

VHF range is mainly line of sight, so antenna height, condition, mounting, connectors, and coaxial cable losses matter. A damaged aerial or connector can make a powerful fixed set perform poorly. Keep the antenna system secure, dry, and visually checked.

A DSC set needs a reliable position source or a current manually entered position and time. It also needs protected power: correct voltage, suitable fusing, sound connections, charged batteries, and a practicable reserve. A handheld has lower antenna height and power, so expect shorter range and manage spare or emergency batteries according to their instructions.