Buyers Guide to Radio Equipment

Most yachtsmen equip their boat with a VHF radio. Since 2002 any new 'fixed' VHF must be DSC compatible and nearly all fit a fully DSC compliant radio.

VHF DSC radios use digital signals to alert other stations that they are being called, just like ringing another telephone. Once contact is made, analogue voice signals are used to communicate on channels that are open for anyone to hear. They are short range and do not involve satellites.

FUNCTIONS

DSC sets have a number of functions and where the set's size has been kept small, controls may be very small, making them difficult to use, especially with gloved hands. Menus are used, much as on a mobile phone, and on some sets the menu structure is not self evident and major functions are sometimes hidden on second or third level menus. Displays are also fairly small.

If all you are buying the set for is to make normal VHF voice calls and to have the facility of having a Distress Alert button, then any shortcomings in the functionality of the set is not likely to be important.

If, however, you would like to use the various DSC functions, such as calling the Coastguard or another boat digitally, you really need to 'try before you buy'. Not all sets are equally easy to use, and price is no guide, so do get some 'hands on'.

The essential functions of a DSC radio are:

• Distress Alert Button - standard on all sets
• Channel 16 over-ride button - normal on all sets
• High power/low power button - often hidden somewhere in the menu structure
• Dual watch button - often missing and replaced by the almost useless (for marine purposes) scan button
• A means of altering the volume - knob or up/down buttons
• A channel selector - knob or up/down buttons
• A squelch control - knob or up/down buttons

Most other functions will be somewhere in the menu structure and will need familiarity before you can use the set effectively.

There are several 'private' channels used by leisure yachtsmen. Yacht clubs use channel 37 and M2 for race control and some marinas in the UK still use channel 37. These are often not easy to find on your set and the problem is not helped by manufacturers using the incorrect terminology. Channel 37 may not be found in the normal sequence of tuning. It may be called (properly) channel M, but is often called incorrectly channel M2, and sometimes on some sets P1. Channel M2 is sometimes called P2! You will just have to read the handbook. Some cheap sets do not have these two channels at all.

HAND-HELD RADIOS:

Owners of smaller boats may well choose to have only a 'hand-held' VHF radio, so let's have a look at these first.

Although there have been a couple of handheld radios with a DSC distress alert button, they have now been discontinued as they don't comply with the regulations as they cannot receive a DSC alert, so no current handheld has any DSC functions - they are purely voice only.

Hand-held VHF radios have a major disadvantage: restricted transmission range. This lack of range stems from two main factors:

• The battery size is strictly limited, so transmitter power is restricted. Some sets manage 5 watts, but others have as little as 2 watts.
• Range is restricted by the height of the antenna, so if you are in the cockpit of your boat, the antenna height will be only a couple of metres.
• Don't be fooled by the fact that you can hear Coastguard 20 miles away - they won't hear you at more than about 4 miles.

A 5 watt hand-held is unlikely to have a transmitting range of more than about 4 miles. A 2 watt radio is more likely to be limited to about 2 miles.

• A further restriction of transmission range will occur if you don't hold the set with the antenna vertical.
• Battery life will be limited, both in use and with the set turned off. Some sets allow the fitting of non-rechargeable batteries to get you out of trouble when the normal battery is flat.
• Some sets use Ni-cad batteries with their 'memory effect' others use Li-ion batteries which are superior.

FIXED VHF RADIOS:

Fixed radios have two major advantages over a hand-held set:

• They have a maximum transmission power of up to 25 watts because they are powered from the boat's electrical system and combined with a masthead antenna, transmission range may be as much as 40 miles when speaking to a coast station with a high antenna
• They will have a DSC capability, allowing a distress alert to be transmitted at the press of one button if you are pressed for time.

Some fixed DSC radios have a complicated menu structure and are not intuitive to use. Some have 'dual station' capability, ie they can have controls say at the helm And at the chart table. Often these more expensive radios have extra functions and are complicated to use - I cannot stress enough - try before you buy.

	Pat Manley

Pat is an Associate Fellow of the Royal Institute of Navigation and has been sailing dinghies since 1959 and cruising yachts since 1984. He is a Yachtmaster Instructor (sail) and Yachtmaster (power) is the principal of 1 to 1 Navigation and sails a Westerly Oceanquest 35. A member of the Yachting Journalists Association, he is a regular contributor to Practical Boat Owner Magazine, he also writes for Fernhurst Books who have published his Diesel Companion, Electrics Companion and Radar Companion. Just published is his new hardback book, Small Boat Maintenance. www.1to1navigation.co.uk