if you have an hangar only for an UAV, I would rather have no hangar at all...
Don't listen to this this is bad advice.
See, this is why I hate so many cooks coming here to stir the broth - you get a bunch of lousy advice from people who frankly are still learning themselves. Listen to Thiel, TimothyC and erik_t because they actually know what they're talking about - the last two are engineers and the first one actually serves in the Merchant Marine. I don't know Novice's background, but he's given nothing but sound advice too.
Anyway, if you're going to field helicopters, having a hangar is a nifty thing. It gives maintenance facilities on-board ship, a nice working space for crews. I've been around enough guys who work on aircraft, including a good friend who is a Marine helicopter tech, and if you told him he doesn't need a hangar, he'll punch you in the face (bear in mind, he's a MARINE) and I'll freakin' help him.
Don't worry about manned vs. unmanned. You get what you need to achieve the mission with. Unmanned helicopters provide a nice, steady camera platform in essence - they can loiter for long periods of time and monitor sea activity. This is
exactly the mission a vessel like this performs. Sure, you can have a manned helicopter if you want, but I'd rather just expand the hull to accommodate it rather than sacrifice a hangar so you can get a bigger helipad.
Plus, drones like hangars. A hangared drone is a happy drone.
Other than that, I'll see what other advice and progress you've had.