I've already talked about Lieutenant Staff, but there are a couple of other navy characters in The Voyage of the Minotaur worth note.
Captain Gurrman is the commander of the HMS Minotaur. He appears infrequently and usually as Iolanthe's dinner guest, but he lives on later in the series as a building in the new colony is named for him.
Lieutenant Baxter is a junior officer on the HMS Minotaur and appears little more than the captain, however he is one of the major characters in Book 4: The Young Sorceress, and if I ever get around to writing the second five book series set in this world, he will be one of the major characters there.
Here is a hint at the possible titles:
Book 0: Return to Brechalon
Book 1: The Sorceress and her Lovers.