The speaker is a sailor's wife, left behind on shore, and the poem is about how heavy and stretched-out waiting feels. It opens by treating "wait" as if it were physically long, though it's only four letters. That small joke carries real weariness: the time ahead seems endless.
She then says she understands water but not ships. The line suggests she knows the sea as a force, something vast and familiar, but can't grasp the vessels or the choices that take her husband away on it. The ship is the thing that separates them, and it stays foreign to her.
The last lines turn inward. Her "poor body" wants to sail, and the only vessel she has is her own bed. It's a sad, slightly wry image: loneliness, longing, and a restless wish to follow him, all shrunk down to a bedroom. The mood is quiet, aching, and patient, with a thin streak of dry humor.