Racking my brain

I read part of a book a couple of years ago, and I've been trying for months to track it down. It is a novel - part of a series, I think - about a girl who has adventures on the high seas. I thought it might have been The True Confessions of Charlotte Doyle, but having read a snippet, I'm certain it isn't.

What do I remember? The girl had an unusual name, a connection to the Cape (or near the Cape) and of course an adventure on the ocean(s). Oh, and that the books are well-written. Last time this happened, it took me years (and finally, very good luck) to track down a book. I hope this time isn't as difficult.