By Phil Davison
April 24, 2020 at 6:24 p.m. EDT

In 1964, the young and rebellious Irish go-getter entrepreneur Ronan O’Rahilly, along with his corps of DJs, started beaming Bob Dylan, the Rolling Stones — and other artists spurned as “a menace” by the staid BBC radio monopoly of the time — from a converted 700-ton ferry off the east coast of England, just outside British territorial waters.

Unlicensed and uncensored, Mr. O’Rahilly’s Radio Caroline was the nation’s first pirate radio station and became the heartbeat of British youths. It broadcast into the wee hours, attracting hundreds of thousands of teenage postwar boom babies who listened in from a transistor radio tucked under their pillow while their parents were listening — perhaps on their downstairs box — to Frank Sinatra and Perry Como on the BBC.

Mr. O’Rahilly, who died April 20 at 79 in his native Ireland, drew an audience of 25 million in his prime and was credited with helping spark the Swinging Sixties and eventually forcing the BBC to “get with it” by setting up its own pop music channels.

Musicians, including Pete Townshend of the Who, have said Mr. O’Rahilly not only helped them break through, but was influential in reshaping Western European musical culture during the edgy days of the Cold War. The Times of London called the Irishman “the godfather of the pirate radio stations which revolutionized British broadcasting in the 1960s.”

Mr. O’Rahilly had named his rusty ship the MV Caroline after President John F. Kennedy’s young daughter. He became a lifelong fan and amateur historian of Kennedy, America’s first Catholic president, and kept a gigantic bust of the leader in his office on the boat and later in his onshore headquarters.

Rebellion was in his DNA: His grandfather Michael O’Rahilly (known with traditional Gaelic reverence as “The O’Rahilly”) was considered by many a leader and martyr of the Easter Rising of 1916, when he was killed by a British machine gun.

His grandson Ronan deliberately chose Good Friday 1964, at precisely noon, to launch Radio Caroline, “nicking” (English for stealing) a new single called “Caroline” by the English band the Fortunes as its theme tune. The first track the station played was the Rolling Stones’ version of “Not Fade Away.” The song’s opening line — “I’m gonna tell you how it’s gonna be” — was Mr. O’Rahilly’s first shot across the bows of the BBC bosses who at the time wouldn’t touch the longhair Dylan or the Stones with a bargepole.

Mr. O’Rahilly and his Radio Caroline story were told, with a high dose of fiction, in the 2009 British movie “The Boat That Rocked” (released in the United States under the title “Pirate Radio”) featuring Philip Seymour Hoffman, Bill Nighy and Kenneth Branagh. The movie was not successful at the box office, possibly because the true story was funnier and more dramatic than the film version.

Aodogán Ronan O’Rahilly was born May 21, 1940, in Dublin into a wealthy business family; his father had owned a private shipping port at Greenore in Ireland’s County Louth. Perhaps influenced by Dylan’s fantasies, Ronan later claimed he had run away from home seven times before he crossed the Irish Sea to seek his fortune in England.

With his Gaelic good looks, charisma and Irish blarney, he set up a music club, the Scene, in London’s Soho district. It quickly attracted young artists drifting into the capital from around Britain, including Eric Burdon and the Animals, jazz/pop pianist Georgie Fame, the Kinks, and the Rolling Stones.

To his admirers, Mr. O’Rahilly was a renegade visionary and a skinflint con man who sometimes liked to find creative ways to leave posh restaurants without paying for his meals.

Mr. O’Rahilly became Fame’s manager and, after the BBC refused to play the artist’s music, the Irishman decided to set up his own radio station offshore. He realized there was an unhealthy relationship between the BBC and the major record labels who were paying BBC insiders to have their tracks aired. The system was called “payola,” described by Burdon in the Animals’ breakthrough track “The Story of Bo Diddley.”

Mr. O’Rahilly bought a disused Danish ferry for 20,000 pounds, sailed it to Ireland, kitted it out with sophisticated radio equipment, huge generators and a 180-foot radio mast and took it to the North Sea just off Felixstowe in England, three miles outside British territorial waters. Radio Caroline was born.

In 1967, the British Labour government, led by Harold Wilson and his key cabinet minister Tony Benn, announced a new law called the Marine Broadcasting Offenses Act. Officials denounced Caroline and ordered it to shut down because it was not paying royalties to artists.

Mr. O’Rahilly’s response cannot be published in a family newspaper, but he kept the sea-born station going even though the BBC stole away some of his initial DJs for its new Caroline-inspired pop programs. Mr. O’Rahilly retaliated, through Radio Caroline, by supporting the victorious Conservative Party in the 1970 general election.

In 1991, the MV Ross Revenge, a former fishing trawler that had replaced the MV Caroline, ran aground on a sandbank off the English coast. “I think there were three DJs and their girlfriends on board. That was the crew,” current Radio Caroline chief executive Peter Moore told The Washington Post. “They were lucky to survive.”

Outside his pirate radio career, Mr. O’Rahilly became manager of model turned actor George Lazenby, who played dashing spy James Bond in the 1969 movie “On Her Majesty’s Service” after Sean Connery temporarily left the movie franchise. Lazenby was presented with a long-term contract to play Bond, but Mr. O’Rahilly talked him out of doing more than the one film, making an ill-advised argument that Bond had become passe.

“Ronan convinced me not to stay on as Bond — I’d be in danger of becoming part of the establishment. Something he rebelled against,” Lazenby wrote on Instagram. Roger Moore soon took over the role. Mr. O’Rahilly instead produced Lazenby’s 1971 action flop “Universal Soldier,” marking the downward trajectory of the actor’s career.

Mr. O’Rahilly was married in 1993 to Catherine Hamilton-Davies, and they lived in London for many years. In 2012, he met Inês Rocha Trindade, who became his partner and cared for him after he was diagnosed around that time with vascular dementia. Survivors include his wife, his companion, Trindade’s son, and three sisters.

His death, in County Louth, was confirmed by Moore. Radio Caroline still broadcasts off the southeast England coast as well as from digital studios, including one in Hollywood that runs a 7 to 9 a.m. breakfast show via its website.

“Ronan was a clever man, sometimes verging on genius,” Moore added. “Eccentric, of course, sometimes unscrupulous, but suddenly kind and warmhearted. A rogue maybe, but a charismatic and lovable rogue. In a pastime populated by unusual people, Ronan was more unusual than all of them combined.”