FOR maximum effectiveness and safety in the covirse of their work life-boats, both conventional and inshore, must have contact with other units involved. They must, therefore, be able to talk to shore stations, aircraft and other craft at sea. During the 1960s the policy evolved of fitting life-boats with two, sometimes three, separate radio transmitters/receivers to enable them to do this, i.e. medium frequency (MF), very high frequency (VHF) and ultra high frequency (UHF). MF has long been the backbone of marine radio communications. It is fitted in all conventional life-boats and until recently was the normal channel for talking to other ships or the shore. UHF was also fitted into nearly all life-boats for talking to service aircraft, generally helicopters; VHF, used for short range communication, was only fitted in selected life-boats where there was a shore station, usually Coastguard, with which the life-boat could communicate.

The last five years have seen a marked increase in the importance of radio communications in many walks of life. For example, the walkie talkie radio is now a common feature in operations ranging from police work to shipbuilding.

At the same time there have been considerable changes at sea, not least in search and rescue communications.

1970 could be taken as the climax for the change in marine communications. By then VHF, the use of which had been spreading steadily during the 1960s, had become the standard medium for communications between two ships or between ships and shore stations within line of sight distance of each other. A glance at the descriptions of new boats in the Fishing News shows that all but the smallest boats, be they Scottish, Irish or English, are fitted with VHF as well as MF. All Coastguard stations, too, are now equipped with VHF.

Largely because of the spread of VHF visual signalling has fallen into disuse, semaphore has died out and the standard of morse has fallen considerably.

The R.N.L.I.'s communications policy has been modified to take account of these changes and all new life-boats are fitted with VHF. Boats already in service are being equipped with sets as quickly as the supply and technical organisa-lion can cope, usually when they come in for survey.

The increasing number of incidents involving helicopters raised a communications problem for there was no direct link between aircraft and coastguard. As a result life-boats sometimes became involved as a clearing house for radio messages between aircraft and shore, receiving messages on UHF and re-transmitting them on VHF or MF.

The obvious disadvantages of this situation led to the installation of sets operating on the VHF marine mobile band in Royal Air Force helicopters. The sets are of the portable type and are connected by plugs and sockets to the aircraft aerial and microphone/headphone systems.

The introduction of marine type VHF in helicopters led to a review by the Institution of the whole question of communications between life-boats and aircraft. An MF frequency was already designated for SAR Scene of Action communications. This was 3023.5 KHz and was within the scope of the ordinary Coastal Curlew or Woodson Clipper set used in lifeboats.

Trials at Padstow and Troon confirmed that life-boats could talk to both RAF Nimrod fixed wing aircraft, and Royal Naval Sea King helicopters using this frequency. The availability of these VHF and MF channels for working with aircraft pointed the way to simplification and economy as well as an increase in efficiency. Once a life-boat was equipped with VHF and had a crystal for 3023.5 KHz fitted in her MF transmitter, the less reliable and expensive UHF could be dispensed with. A programme is now under way to do this and the UHF sets are being withdrawn as MF radios are crystallised on the new frequency and VHF is fitted in those lifeboats which do not already have it.

As any life-boat radio operator knows, the medium frequency band is becoming increasingly congested, particularly on the calling and distress frequency. Various changes are taking place to overcome this, the most significant being the introduction, by international agreement, of the single side band (SSB) type of emission as from 1st January, 1973. This will have the advantage of giving to MF communication the clarity and freedom from interference normally associated with VHF. It also enables about twice as many channels to be fitted into a particular band of frequencies as is possible with the current form of emission, known as double side band (DSB). Without going into the technicalities it is sufficient to say that it is not possible to 'read' a SSB signal with a DSB receiver. Fortunately there is a half-way stage between DSB and SSB known as 'DSB compatible' and all SSB sets arc' able to transmit by this means. In addition the congestion on the calling and distress frequency is causing much more use to be made of working frequencies for everything except actual distress calls or the briefest exchange of messages as a preliminary to shifting to working frequencies: even in distress working lengthy discussions not involving third parties should take place using working frequencies. All new life-boats' MF radios are fitted with crystals. Two of these are for shipto- shore use on both receiver and transmitter, one pair for working with the Coastguard and the other for use with the appropriate Post Office coast radio station.

Because of the very widespread use of MF and the number of DSB sets at sea, the International Telecommunications Union has specified a 10-year change-over period before all MF transmissions have to be SSB. During this period all transmissions on the calling and distress frequency have to be of the DSB compatible type. This is particularly fortunate for the Institution since SSB radios at present on the market cost between two and three times as much as DSB and they are more complicated to operate.

At the present time most life-boats are equipped with the Coastal 'Curlew' MF set.

This has been a very faithful servant and not the least of its merits is that it is simple to operate, but the sets are now 10 years old, their radiated power is too low for modern conditions, and they are due for replacement. Since the life of a new set will have expired by the time SSB becomes compulsory it has been decided to replace a number of the 'Curlews' with the 'Clipper 50' set made by Messrs.

Woodson, of Aberdeen, which is twice as powerful and more versatile than the 'Curlew'.

A major operation is now in progress to install 45 of the new sets and displace a corresponding number of Coastal 'Curlews' in life-boats round the coast.

The set first adopted as standard for inshore life-boats, and indeed the only one on the market coming near the requirement for robustness and water-proofing needed in these boats, was the Pye Commander. As with VHF in large life-boats a policy of selective fitting was adopted. Unfortunately sets were not always available, as they were manufactured only when a sizeable military order was in hand.

This made it extremely difficult to keep up with the needs of the coast.

No one who has been out in an inshore lifeboat could fail to realise the importance of radio communications or the feeling of security and confidence engendered both ashore and afloat by a radio channel that is really reliable in difficult conditions. Much thought has therefore been given to the problem of finding improved inshore life-boat radio: the latest development in this field—the Derritron 'Portable Seaphone' —has now been tried, accepted and will shortly come into service and from now on all inshore life-boats will be fitted with radios. Much care is taken to select the best possible radio equipment for installation in life-boats and a considerable organisation exists to inspect it, to ensure continued serviceability and to repair it when it goes wrong. In skilled hands it can be of enormous advantage in helping the life-saving effort, but clearly it is as important that the operators should be well trained as that their equipment should be of the best quality.

A life-boat should never be thought of as being on her own at sea. There are always two or three people, apart from the honorary secretary, who are keenly awaiting information.

These will probably include a Post Office coast station as well as one or more Coastguards and perhaps the life-boats from flank stations, which may be at sea. In a major search operation the number of individual units may easily reach a score or more. When at sea on service therefore a life-boat should try and signal her position and intended movements (PIM) at least every hour so that those co-ordinating the operations, or awaiting news ashore, may know what is going on.

Finally, a radio transmission has a considerable effect on the 'image' of the Institution.

A stranger ashore listening by chance on the distress frequency during a gale and hearing a coast station repeatedly calling a life-boat and getting no reply can conjure up images of disaster with no difficulty at all when all that has happened has been that the loudspeaker in the life-boat has been switched off. Correspondingly, crisp efficient radio communications are highly re-assuring to a casualty and leave those anonymous listeners with a true idea of what the life-boat service is..