Green’s Dictionary of Slang

1. (US black) a homosexual.

1941

A. Lomax Mister Jelly Roll (1952) 45: I suppose he was either a ferry or a steamboat, one or the other, probably you would say a ferry because that’s what you pay a nickel for – and that was the cause of him going to Chicago about 1906. He liked the freedom there.

2. (Aus./US) a prostitute.

1966		Trimble 5000 Adult Sex Words and Phrases.
1986–7		Maledicta IX 148: The compilers ought to have looked farther afield and found: […] ferry (short rides).