Why your VHF is your most important safety tool

On a catamaran, whether you are hopping between Solent harbours or crossing to the Channel Islands, your VHF radio is your direct line to help. It brings weather forecasts, port operations, and emergency services. But unlike a mobile phone, it needs regular care. Salt, vibration, and UV take their toll. A simple routine keeps it reliable when you need it most. Without it, you are cut off from the network of sailors, harbours, and rescue services that keep coastal cruising safe.

Antenna and coax: the weak link in most installations

Most VHF failures start at the antenna. On a catamaran, the masthead is high and exposed, and the wide beam means longer coax runs. Inspect the antenna base for cracks. Check the coax cable where it enters the mast or cabin. Look for chafing, kinks, and water ingress. The PL259 connectors at both ends should be dry and tight. Use self-amalgamating tape and silicone grease to seal them. If you can, check the standing wave ratio (SWR) with a meter. A poor connection reduces your range dramatically—sometimes from twenty miles to two.

• Masthead antenna: secure, with no corrosion on the whip or base.
• Coax cable: no sharp bends, no crushed sections, and no signs of water.
• Connectors: clean, tight, and waterproofed with tape or grease.
• Grounding: not usually needed for VHF, but ensure the radio chassis is not live.

Testing DSC and your MMSI

Digital Selective Calling (DSC) is a powerful tool, but only if it is programmed and tested. Ensure your MMSI is entered correctly and locked. Connect the radio to your GPS so your position is transmitted automatically with any alert. Test the DSC function by sending a test call to a nearby station or using the radio's built-in test. Check that the distress button is protected from accidental activation. In the UK, you can do a radio check with a local marina or the coastguard, but always follow proper procedure.

• MMSI: correct and locked in the radio's memory.
• GPS data: displayed on the radio screen.
• Test call: to a friend or marina, not on channel 16.
• Distress button: covered or protected from bumps.

Power and batteries: keeping the radio alive

VHF draws little power on standby, but transmitting uses more. On a catamaran, you likely have a large house bank. Still, a dedicated fused circuit is wise. Check the fuse, the breaker, and the connections at the back of the radio. Corrosion here causes voltage drop and poor performance. Check the voltage at the radio's terminals with a multimeter; it should be at least 12.5 volts with the radio on. Keep a handheld VHF as a backup, charged from a 12V socket or USB. Modern lithium batteries hold charge well. Test the handheld regularly. If your main radio fails, the handheld is your lifeline.

• Dedicated circuit: fused and separate from other electronics.
• Terminals: clean and tight, with no green corrosion.
• Handheld: charged after every trip, stored in a dry place.
• Spare power: carry a power bank or spare batteries.

Routine checks and weather updates

Make VHF part of your daily routine. Each morning, switch on and listen to the inshore waters forecast. Check the volume and squelch. If you hear nothing but static, try adjusting the squelch until the noise just disappears. Do a radio check with a friend or marina. Note any interference or weak signals. Keep a log of your checks. This habit means you will spot problems before they become failures. Also, practise your Mayday procedure silently, so you know the words if you ever need them.

• Daily listen: five minutes on channel 16 and your working channel.
• Radio check: brief transmit on a clear channel.
• Weather: note the forecast time and any warnings.
• Log: record battery voltage and any issues.

Troubleshooting common VHF problems at sea

If you lose reception, first check the antenna connection. Then check power. If you can hear but not transmit, the microphone or push-to-talk switch may be faulty. If you get a high SWR warning, the antenna or coax is likely damaged. On a catamaran, the masthead is hard to reach, so carry a spare antenna and a coax jumper. You can also use a handheld as a temporary fix. Do not rely on a faulty radio for your safety.

• Reseat connectors: unplug and replug every connection.
• Try another antenna: a spare or a temporary one.
• Use handheld: as a backup for short-range communication.
• Call for help: on channel 16 if you are in distress.