So, obviously trying to rebuild a hulked battleship, and make yourself the big A on the block is a frequently voiced idea, and a rarely acted upon one, for numerous reasons, but while they haven't given us much of anything on battleships, minus stats for da Wurldbreaka and Kroot Spheres, would they be their own class? It might seem a dumb question, but I suppose it all comes down to a matter of size. Grand Cruisers and Battle Cruisers are each allowed to use "Cruiser class" parts, even though they are supposed to be somewhat bigger, and it is a rare component that actually says "bigger than cruisers only". Are Battleships truly still so much bigger that you'd need "Battleship components, or would cruiser bits do? In the event that only bigger is better, would there be any way to get them without every goober in the Expanse knowing? Even Winterscale doesn't have battleships, sometimes even Space marines limit themselves to more cruiser-scale vessels, and that means getting the parts for such an endeavor would be impossible quietly, only partly barring raiding every haunted Space Hulk you can find for hopeful "big ship" parts.

I suppose this might very well explain why such a thing hasn't occurred, but would it even be possible to get the parts, quietly or loudly, or should every wrecked battleship just be viewed as a cute joke, hopefully with an interior filled with loot worth pilfering? Lots of people have talked about rebuilding the Light of Terra, or some other vessel, but time and cost be damned, would the parts needed just still be unavailable? If I'm the Navy, and you want a battleship component, that must mean you have a battleship, and I don't want to have to fight it, someday, if you go from Rogue Trader to full-blown rogue. Why would I ever willingly sell it to you?

Warships are a luxury. Nations only build them to guard their lanes of commerce, mostly from pirates. Many don't even bother with that, since there's always another government out there that will do the job for you, assuming they're friendly. Ships-of-War are specialized to do combat with other like vessels.

We jet around with starships that have 5-15% of their internal space alloted to cargo and make a baseless assumption that this can somehow prove profitable. We do this in the name of space opera. At some point we push the envelope of credulity. In Rogue Trader the edge of that envelope is battleships.

Now generally I'd think that battleships carry different weapons, especially for main armaments. But the single most powerful weapons in 40K space combat are nova cannon, and they can be carried by cruisers. Battle cruisers are supposed to be armed much as battleships, but with less armor. So, I'd say that the weapons in the books are likely the same as BBs carry, though there'd probably be some additions, and BBs would have more slots.

I would assume that a genuine imperial battleship is actually bigger than a battle cruiser, given how the fluff I read on them treated it. Granted I also read a piece stating battle cruisers and battleships were the same size, so take your pick really. Personally I like to imagine the battleship is about 10+ kilometers, a mass conveyer but sexier and purely outfitted for annihilation of entire solar systems. However everything I claim to know on them states the battleship is its own class, and only built at places like Mars, and then only VERY rarely, given the resources and its crew of a quarter million people. It would be the dreadnaught sitting in the core of the largest fleets, probably plowing as magnificently as possible into the core of the enemy fleet, shrugging off hits with its probably four or so voidshields, and giving everyone around it a taste of every horrible weapon the imperium has ever glued to a ship. That is also why there are so few, and as I understand, held in the rear unless truly needed.

Battleships are huge . Even by the standards of 40k.

Salvaging one, unless you somehow managed to find one in near-mint condition, is going to take decades, and actually fitting it out properly, quite possibly over a century. It's a major endeavour, quite possibly multiple endeavors, and quite possibly the entire process could be turned into a campaign in its own right.

After you've found it, you need to talk the Mechanicus into providing teams of tech-priests to assist you in surveying the hull to determine what can be saved, what needs to be gotten rid of immediately, what can be left to wait for the shipyard and what needs to taken care of immediately, before the ship can be moved, etc. Before you can send in survey teams, you need to pour in kill teams to clean out any undesirables. You also need to provide security for the salvage site, acquire tugs to safely bring your haul back to a shipyard capable of handling a battleship and willing to take your battleship in - and there aren't going to be many places that can support a battleship, much less the kind of extensive refit and rebuilding that you'll need.

Battleships would be their own class ... and they'd have a lot of weapon slots and loads of space to work with. They'd be slow and not very maneuverable, but they'd have lots of void shields, a high base turret rating, and high base armor.

http://fc06.deviantart.net/fs70/f/2014/171/0/1/size_comparison___science_fiction_spaceships_by_dirkloechel-d6lfgdf.jpg

Lah de dahh...

It's not THAT much bigger than a Grand Cruiser. It's just BETTER. A Universe is bigger...

I respectfully disagree. I don't think a Universe is bigger than a BB, and I base that on BFG structural hits. You can make the argument that structure is more than simply space (and I'll grant you it's a good argument) but I'll still call it the difference "armor." I'm thinking that BBs have somewhere in the range of 100-120 space, though I've never really parsed it out (NO WAY I'm letting my players have one!!!)

Looking at BFG BBs, it would appear that said BBs have 7 cruiser "batteries" (the Oberon seems to have 10!)

Given Mathhammer, I'll just give the BBs lots of armor and they can take a pounding for days, if not weeks, and call it a day. My players can feel envious and that's a good thing, as they'll also feel scared.

T'be fair, the Universe is bloody huge. And would be built with lots of large empty structural spaces for cargo holds, whereas a Bship nominally is going to have fewer large empty structural spaces, as they're built to support lots of gun mounts and armor.

As far as Bships go ... frankly, I don't think that the sizing system is particularly accurate or a good comparison of volume. At least, not with anything above a frigate or so in size, since doubling the dimensions is 8x the volume, which basing off of raider/frigate volume stats, would probably place a Bship at 200+ space. The things are huge, and have space for all kinds of ancilliary equipment to be installed.

I kind of have to agree with Errant Knight - even supposing the players find a bship hull that can be salvaged, and proceed to do so, by the time the process is finished and the ship is rebuilt, the PCs should have gotten to the point where they get to graduate to NPC-dom (or unplayability) and they can play new characters in the Dynasty ... who aren't flying the Dynasty's Most Valuable Ship around. That, or they have arranged to deliver the Bship to the Navy or Mechanicus and have made a huge profit off of the affair, and have new friends in high places.

I'd give Bships enough armor to make most macrobatteries nearly useless without scoring crits. They'd probably need special rules about taking morale and crew damage, because they're so big and have such huge crews that they can take that pounding and not need to worry about morale/crew damage unless they've actually taken serious damage.

Because I actually have the stats for a battleship-sized plasma drive, and because that's bound to be one of the hardest things to find for one, I figured I might as well post it here:

Mars-Pattern Plasma Drive (Battleship) 145 Power Generated, 22 Space.

It's enough to power the tons of stuff you can fit on such a huge ship with around 130-160 Space. Which is what the rules I ended up using for one (which sadly I no longer have) were around.

Also an elegantly simple rule to address the whole 'so big most stuff barely even affects us' thing is to simply have crew population and morale doubled (as well as any modifiers to those, but not modifiers to losses).

I'm curious where you got the stats for the battlship plasma drive. Also, on the size-comparison website. BB The Retribution seems to have 2.7 times as much internal space as the BC Mars.

The main hurdle I've had with this is your built-in assumption that you can just find Battleship parts. Battleships aren't constructed anymore, and just look at all the fluff about how Grand Cruisers are proving to be too much hassle to maintain anymore. I would definitely not allow Cruiser pieces to be plugged in there, because while Battle Cruisers or Grand Cruisers started with the design philosophy of a Cruiser, the Battleship started off as its own class.

You're not going to find a partially-operational Battleship Plasma Drive or compatible weapon system just sitting at a scrapyard in Footfall. Even if you could get it operational, the AdMech or the Navy would probably do everything in their power to take it away from you.

By find, I meant find the stats for out of game.

In game, yes I am going to agree with you on that.

Also, my GM used homebrew rules for a battleship in our first game of RT. I've asked about whether he still has it and he doesn't know where he got it.