Dead Deep, published for World Book Day, is a novella set between the first two Vampirates novels, Demons of the Deep and Tide of Terror. Connor, Jez and Bart get some shore leave, and spend it in most surprising company. (Though if they knew a bit more about mythology, they'd have had second thoughts about boarding the Lorelei.) Fun, thoughtful and an interesting take on 'disability': and the narrative, with its twist, doesn't alter the events of either of the main-series books.
Somper hits a good balance between the realities of 'a pirate's life' (Connor, who's 14, gets accosted by a raddled whore) and sensibilities of target YA readership (he rejects her for being raddled, not for .. professional reasons). There is strong drink aplenty, and pleasurable company too, yet the general mood is more of a bunch of teenage lads out on the town -- and, optimistically, on the pull -- than of mayhem and murder and black-hearted wickedness.
One major snipe, though:
Two fathoms below the surface of the ocean, [character] takes his rest. It's a place as far removed from light as you can find on this planet.
Oh no it isn't. I can dive two fathoms without trouble. Two hundred fathoms? Two miles? A silly mistake but an irritating one. A decent proofreader should've spotted this, even if the author overlooked it.