Lifeboat was born when the Maritime Commission asked 20th Century-Fox head Darryl F. Zanuck to make a film about the menace posed by German U-boats in the North Atlantic shipping lanes.
At the same time, Zanuck had signed a deal with independent producer David O. Selznick to have Alfred Hitchcock direct two films for the studio during a 40 week period. The director had long dreamed of facing the technical challenges of filming in a single, small setting, at one point considering a film set in a telephone booth. When asked what he wanted to work on, his first suggestion was something set in a confined space, which made Lifeboat a natural choice for him.
Zanuck paid Selznick $300,000 for Hitchcock's services, of which the director got less than half. His extensive loan-outs, with Selznick making a considerable profit off his services, would be a sticking point with Hitchcock and Selznick and lead to the director's moving into independent production when his contract ended.
Hitchcock's first choice to write the story was Ernest Hemingway, but the writer was already obligated to other films.
Hitchcock went through several writers to get the screenplay he wanted. The first, novelist John Steinbeck, felt constricted by the director's demands that the entire film take place in the lifeboat. He turned in a novella based on interviews with seamen who survived submarine attacks and told from the viewpoint of a sailor with leftist leanings. Hitchcock felt the story unusable, so he hired Harry Sylvester to work with Steinbeck on a scenario that would eventually be published in Collier's magazine (November 13, 1943). At that point, Steinbeck left for Europe to cover the war as a correspondent. Hitchcock would later write "Lifeboat was a group story lasting several days and within the narrative [were] a number of sequences. These were well written but I found they were 'no scene' scenes. By this I mean that the little sequence might have a narrative value but in itself is undramatic. It very obviously lacks shape and doesn't have a climax as a scene on the stage might." (Alfred Hitchcock, quoted in Bill Krohn, Hitchcock at Work) Hitchcock then brought in first MacKinlay Kantor and two weeks later Jo Swerling. When he still couldn't get the script he wanted, he rewrote all of the dialogue himself, then hired Ben Hecht, who had also done a final polish on his Foreign Correspondent (1940), to do revisions. Other writers mentioned in Fox's files include Hitchcock's wife, Alma Reville, actress Patricia Collinge, Albert Mannheimer and Marian Spitzer. Swerling was the only writer credited with the screenplay, with Steinbeck credited with the original story.
The first actor cast in the film was stage star Canada Lee, cast as the black steward Joe. Fox borrowed Hume Cronyn and John Hodiak from MGM and cast their own contract player Mary Anderson, whom they were hoping to develop as a leading lady.
Having failed in her first attempt at film stardom in the early 1930s, Tallulah Bankhead was eager to accept the leading role in a Hitchcock film. She even accepted the relatively low fee of $75,000 for her work, even though she was coming off two big stage hits, The Little Foxes and The Skin of Our Teeth. Her only stipulation was that she never say "Darling," for fear audiences would think she was playing herself. It was her first starring role in a film in 11 years.
Contrary to myth, Hitchcock did not storyboard every one of his films from beginning to end. Many of his most famous storyboards were actually created after the fact for publicity purposes, which helped give rise to the legend. For Lifeboat, however, he did some of his most extensive storyboarding, a necessity when working within the confined space in which the film was set. The director frequently departed from his storyboards for the film to meet specific demands of day-to-day shooting.