The story
From dream + boat, probably suggesting a person “carrying” or embodying the dreams of another; the term appeared in some 1930s and 1940s love songs, referring to a metaphorical boat carrying a lover’s dreams, such as “When My Dream Boat Comes Home” (1936) written by the Canadian-American bandleader Guy Lombardo (1902–1977) and “Someone’s Rocking My Dreamboat” (1941) by the American songwriters Otis (1898–1970) and Leon René (1902–1982), and Emerson Scott.
Etymology from Wiktionary, CC BY-SA 4.0.