At 5.55am, Tommy Vance gropes out of the bunk 'feeling like a reject from the glue factory."

At 6.00am, teeth brushed, but shoeless, he has relieved Robbie Dale behind the microphone and begun his three-hour show with a cheerfulness self-imposed with such pain that it should be reported to the Council for Civil Liberties.

To cut his studio-to-bed time, Dale has been on the air wearing his pyjamas. "Sometimes," he says, "I wear nothing but pyjamas for a fortnight."

At nine, a breathless Mike Ahern, 'Fink University' written across his T-shirt and slopping coffee, arrives to take over the turntables.

Another timeless day has begun on Radio Caroline South. Another 24 hours of brisk pop music and ruthless happiness.

The ship - 470 tons of throbbing pop culture - is manned by seven disc jockeys. They rush in and out of doors, toing and froing to studio or beds with such frequency and purpose that it is like being locked in with the Marx Brothers.

The disc jockeys are what is known as colourful. They look as if they dressed in the dark at a jumble sale. On the air they insult each other, abuse the records - "What a dirge, take it off!" - commit indiscretions and 'take some shocking liberties' with the listeners.

The formula is successful. The offshore stations have an estimated audience of 24.5 million. And Caroline claims the biggest chunk of it.

Dave Lee Travis is chief DJ of Caroline South. He is 21, has hair and a beard resembling a thick knit balaclava, a fringed Buffalo Bill jacket and more rings than a youth hostel bath.

"Our audience identifies with us," he says. "They like us because they recognise us as normal, human, fallible people like them and not remote, anonymous impersonal voices."

They all have a highly developed sense of the station's superiority and do not even bother to monitor the competition.

Despite the glamour that accrues to them - "listeners see us as swashbuckling pirates defying authority and I suppose that's romantic" - the life is monotonous and monastic.

They work two weeks on and one week off and during their time aboard the 150ft long boat, may never step on deck. It is cosy but restricted. The food is good, but the life is celibate and rigidly governed by round-the-clock schedules.

The beer is free (no spirits) and the cigarettes are 1s for 20, but in the frequent gales it is difficult enough to stand, let alone provide the brittle cheerfulness demanded on the air, and ten DJs have had to quit because of seasickness.

And, ironically, while broadcasting 24 hours a day to millions, they cannot have conversations with the shore because it is illegal to use their radio telephone. Because of the sleep and transmission rotas they see little of each other, but try and gather to share the communal TV addiction to Thunderbirds, Batman and any show with girls.

The pay: between £25 and £60 a week, depending on service and experience, with little opportunity to spend it.

"We would be better off in the nick or in the Foreign legion really - at least we'd get some exercise," says Johnnie Walker, a former car salesman in Birmingham with a precocious line in chat and a consequent swooning following among girl listeners. He came from Radio England in November.

"It's a really hard scene and we earn every halfpenny of our bread. We may be on the air for six hours a day, but we frequently don't know what day it is.

"I keep taking my vitamin pills, but I've lost 1.5 stone on the boats. Twelve months is enough if you don't want to end up in the nuthouse."

Travis is the longest server, with 15 months: "The equivalent of 15 years with the same firm ashore."

They endure it because they are bitten by broadcasting.

"This place is a drag," says Tommy Vance, the first established British DJ in America and formerly of Radio Luxembourg.

"It really is an abominable existence, but I'm involved with broadcasting and this place has a microphone and a 50 kilowatt transmitter, which I can use exclusively for many hours a day. We all enjoy the work but recognise there is more to broadcasting than playing pop records." He wants to read poetry on the (BBC) Third Programme and be a film director.

The most recurrent word aboard - flung affectionately at each other when the tapes of broadcasts are replayed is 'Meglo'.

The BBC's pop coverage is proscribed as 'square'. But they all envy the status of the country's top five DJs - Jacobs, Murray, Freeman, Savile and Simon Dee - projected on it.

Watching The Five on Juke Box Jury, Mike Ahern, an energetic little Liverpudlian who used to be a grape-picker erupts indignantly: "What do they know about it? Simon Dee is the youngest and he's 29. And Savile must be 50. They're all out of touch. The average age on Caroline is only 22."

"Meglo, Baby," shouts Robbie Dale.

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