Two short lines set up a quiet comparison. Ships sit full and content because the wind fills their sails, and the speaker feels the same way about a book. Wind is what a ship needs to become itself, to move and do what it was built for. By putting the book alongside it, the speaker suggests reading does the same for them: it gives them the push they need.
The word "satisfied" matters. It doesn't suggest wild excitement, only a deep, settled contentment, the feeling of having exactly what you need. The mood is calm and unhurried, almost like a held breath. There's also a gentle humor in the scale of the comparison, since a whole fleet is matched with one small book, yet the poem treats them as equals. The title, "Inspiration," hints at the link: wind and breath share an old connection, so a book can fill a person the way air fills a sail.