The second book of a series is likely the hardest to write. If you don't do something slightly new with it, it feels like a) the first book and b) a placeholder on the way to the third book (especially if you're writing a trilogy, which he is not). Therefore, Lynch had a great deal of fun with this book by creating a pirate-drenched swashbuckling adventure.
It's not that hard a stretch. Locke and Jean are, after all, thieves. Stick 'em on a boat and they're pirates. Except they're not really, and that's where Lynch has a great deal of fun with his protagonists. If conceivable, he puts them in even more dire straits than in the first book - many of those straits revolving around their complete and utter lack of knowledge about the sea and sailing - and then does what all good authors must at the end of Book Two. He creates the kind of situation that seems on the surface like it is insurmountable. (Like at the end of Season 2 of Farscape when Aeryn and John... oh, never mind, no one's watched that show but me.) I have no fear that in Book Three he will find a way to spin the story back in favor of our favorite thieves.
There were even some bits of the story that made me weepy. He has a way of making us care deeply for his fictional personalities, which I find more than a little astounding because, let's face it, these guys are, well, thieves. Gentleman thieves, yes, but they're still thieves from and on the wrong side of the tracks.