Drama and routine on the 24-hour watch

· Swamped by heavy seas in the Channel, a pitching freighter sends out a distress call....

· In a quiet Hampshire village a sailor's wife is surprised by a birthday bouquet of flowers from her husband.

· A tanker captain tends an injured seaman, guided by the voice of a doctor many miles away....

· A businessman on a cross-Channel ferry gives instructions to staff in his London office....

Unrelated incidents, yet all with a common link: Niton Radio, on the Isle of Wight.

Now operating from a new site, Niton Radio is one of 11 Post Office coast radio stations dotted round Britain's shores.

Through them pass a continuous stream of messages - some urgent, some routine - to and from ships at sea. Niton alone handles 35,000 radiotelegrams and 65,000 radiotelephone calls a year. The figures are growing all the time.

Niton has a history going back many years. In September 1909 it was one of six stations which the Post Office bought from the Marconi International Marine Communication Company to provide a medium-range distress and radiotelegraph service for the 286 British ships then equipped with radio.

Last year Niton Radio handled over 91,000 separate calls to or from ships at sea. From liners to containers Niton has also seen big changes in the ships themselves, and in their methods of communications.

Pre-war, the regular daily arrivals and departures from Southampton included such welt-known names as the Cunarders Queen Elizabeth, Queen Mary, Aquitania and Mauretania, the P & 0 Strath' liners, the Royal Mail Line's Asturias and Almanzora, the Union Castle's Athlone Castle and Stirling Castle.

Immediately after World War II many of these ships were still in service. But now, while some passenger vessels still run, most of the ships that navigate Spithead and the Solent carry bulk cargoes or containers. They are perhaps less beautiful but often larger, more numerous and more demanding in their communication needs for safe and orderly arrivals and departures, and for servicing and stevedoring facilities.

It has largely been the need for rapid communication and rapid decision that has led to expansion of the radiotelephone service and its extension into the field of yachts and pleasure craft. A coast station's most important task is to be constantly on the alert, both by radiotelephone and radiotelegraphy, for calls from ships in distress.

In 1974 Niton broadcast 180 distress calls. When such a call is heard, all routine work on that frequency stops while the station alerts the Coastguard, sends particulars of the distress to other ships and maintains communication with rescue vessels, the Navy and Lloyds. It also maintains a close liaison with the RNLI. Like other coast radio stations, Niton also plays a part in preventing distress and casualty incidents. Last year it transmitted over 4,800 navigation warnings, 1,500 weather bulletins and 950 gale warnings, and dealt with 36 cases of medical advice and assistance.

Why a new Niton? Several factors led the Post Office to move Niton Radio control and its receiving aerials from the old site at Niton Undercliffe to St Lawrence, two miles to the east.

First, a new site was needed to enable the services to expand, to keep pace with a continually growing number of calls, especially on VHF. Second, at Niton Undercliffe there was a danger of a possible landslip affecting the station. And third - because the transmitters and receivers were so close to each other- mutual interference between them was creating a problem at the old station. The transmitters are now at Rill Farm, 3½ miles west of the old station and 5½ miles away from the receivers.

Finally came the necessity to re-equip all coast radio stations to meet the international requirements for single-sideband (SSB) radiotelephone communication, which gives improved speech quality and range and takes up only half as much radio bandwidth.

Conserving bandwidth is vital in an area of radio congestion such as mid-Channel, where on average some 320 deep-sea vessels pass each day.

The station provides multiple-call (several calls at once) working on VHF and MF or a combination of both, and selective calling (to particular ships) for rapid alerting.

Eventually radiotelex will allow the transmission of large amounts of information between ship and shore. The new Niton will improve the quality of radio transmissions, reduce delays and allow new facilities to be added without impairing existing services.