From “John Einarson Remembers” on facebook...
(John Einarson is regarded as one of North America's foremost music historians.)

“March 21, 1966, The Beach Boys released the single "Sloop John B," a traditional tune from the West Indies originally titled "The John B. Sails" credited to poet Carl Sandburg and Lee Hays of The Weavers. It was the lead single off their 11th studio album, Pet Sounds. The song peaked at #3 in the US on the Billboard Hot 100 chart, #2 in the UK, and #1 in several other countries including Canada. The original song dates back to 1916 and had been recorded by a number of artists including The Kingston Trio. There have been many recordings of the song with variant titles including "I Want to Go Home" and "Wreck of the John B".

Jardine was a keen folk music fan and he told Brian Wilson that the Beach Boys should record the song. As Jardine explains: "Brian was at the piano. I asked him if I could sit down and show him something. I laid out the chord pattern for 'Sloop John B.' I said, 'Remember this song?' I played it. He said, 'I'm not a big fan of the Kingston Trio.' He wasn't into folk music. But I didn't give up on the idea. So what I did was to sit down and play it for him in the Beach Boys idiom. I figured if I gave it to him in the right light, he might end up believing in it. So I modified the chord changes so it would be a little more interesting. The original song is basically a three-chord song, and I knew that wouldn't fly." The backing track for the song on July 22, 1965, at United Western Recorders, Hollywood, California.

The vocal tracks were recorded over two sessions. The first was recorded on December 22, 1965, at Western Recorders, produced by Wilson. The second, on December 29, added a new lead vocal and Billy Strange's 12-string electric guitar part. Kent Hartman, in his book The Wrecking Crew, described Billy Strange's contribution to the song. Brian Wilson called Strange into the studio one Sunday, played him the rough recording, and told him he needed an electric twelve-string guitar solo in the middle of the track. When Strange replied that he did not own a twelve string, Wilson responded by calling Glenn Wallich, the head of Capitol Records and owner of Wallich's Music City. A Fender Electric XII and Twin Reverb amplifier were quickly delivered (despite the shop they were ordered from being closed on Sundays), and Strange recorded the guitar part in one take. Wilson then gave Strange $2,000 to cover the cost of the equipment.

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