Carl ultimately overdubbed a lead vocal onto the song's first part, the original backing track dating from November 1966, as well as backing vocals. Two organ overdubs were also recorded. The second movement was composed of the December 15, 1966 solo piano performance by Brian, augmented with vocal and Moog synthesizer overdubs. Carl reworked the refrain from another unreleased "Smile" song, "Child Is Father of the Man", into the coda of "Surf's Up". Bruce Johnston recalled, "We ended up doing vocals to sort of emulate ourselves without Brian Wilson, which was kind of silly." Al Jardine sang the lead vocal on this section. Rieley said, "we all got involved in final tag. ... I'm on it a guy who worked for us part-time, Bill DeSimone, is on it. He just sings 'Hey, hey.' But it is integral to the tag on the record. That was a lot of fun ...". Writing in a 1996 online Q&A, he wrote that Brian had "stated clearly that it was his intent all along for Child to be the tag for Surfs Up."