Lyric discussion by you_underwater 

Cover art for Blueberry Boat lyrics by Fiery Furnaces, The

i've so far thought of the girl waving goodbye as a prostitute, advertising herself for the next time the sailors are in port and sneering at the captain's naievete in thinking she's an innocent sister or girlfriend. if the captain is meant, as i guess, as a female, there's another layer of mockery there.