Dave Bonta's short poem turns going to bed into a voyage. The speaker says they become the captain of a ship at night, and the moment of lying down becomes a departure. Sleep, or the dreaming that comes with it, is the sea they set out on.
The wording is quiet but a little odd. "Gone again to bed" suggests a habit, something repeated night after night, while "setting out afresh" makes each night feel like a new beginning. Then comes "our armed fleet." The shift from "I" to "our" suggests the speaker isn't alone: others may be sailing too, perhaps everyone who sleeps. "Armed" adds a slight edge, as though the night carries some danger or needs defending against.
The mood is calm, playful and a bit mysterious. There is a sense of quiet confidence, even pride, in taking command of the dark. The poem doesn't explain itself, so the image stays open for you to fill in.