Forgive me if I'm posting this to the wrong sub-forum -- first-time poster here. I am curious, though, about whether there are actual stats for Battle Barges available, or if they'll be released in an upcoming supplement. I know the Battlefleet Korunus supplement of Rogue Trader doesn't have anything for them in starship hulls for making one there, and as a potential GM, it would be nice to have such stats on hand.

No, last time I reviewed RT books there were no specific ships, guidelines, or options to creating a space marine vessel.

I would like to see decent rules myself. Problem is, space marine ships are to your standard Imperial ships as space marine power armour is to flak (or carapace for those really fancy Impy ships) armour, they're just that much more whiz-bang. The admech puts all the neat toys in them, they kind of have to for them to survive orbital insertion, fight space battles, operate away from supply for long times, co-ordinate a complicated ground and/or air/space battle, transport a few to a few hundred of the Emperor's finest, and all this with a very small crew. Stuff like teleporters, advanced automation, standard exterminatus gear (on Battle barges at least), advanced comm-gear, thunderhawks and the stuff to service them, boarding torps, large and complicated training environs for their crew, and all the equipment for the marines are all stuffed into these ships.

Battle barges are crewed by a combination of servitors (as per usual ships) and highly-trained chapter serfs - the failed Astartes recruits and their families. These supposed failures are still highly trained, tenacious individuals easily the equivalent of veteran imperial guardsmen or elite naval personnel and they are supported by a lot of autonomous and machine-spirit driven systems on board the Astartes ships.

The ships themselves have incredibly powerful propulsion and shield systems and many metres of ablative armouring so that they can punch through enemy fleet formations and disgorge their Astartes contingents to where they can do the most damage (be it another ship or a celestial body's surface). They feature powerful macrocannon batteries and supersized guns called bombardment cannon that can annihilate ground based defensive positions and cripple enemy ships stupid enough to get in their way. Their ships do have some weaknesses however - they are not the most manouverable of craft, instead favouring straight line speed and armour to smash their way through whatever stands in their way. They also do not have large complements of strike craft for attack or defense, instead relying on their versatile Thunderhawk gunships though these are limited in number.

Add to this the fact that boarding actions are easy to repulse due to the large number of astartes on board, readily available equipment and supplies and things like librarians being excellent at pre-empting combat, enemy tactics etc and you have some of the most efficient and fearsome warships in existence.

I seriously do not think stats for them would ever be useful in Deathwatch. The game doesn't focus on naval warfare, not does it require the players to do anything more than squad level combats. Similarly whilst Rogue Trader could potentially have stats for Astartes vessels, the game really would be jumping the shark if its getting to the level where Rogue Traders are fighting Astartes.

A few corrections:

Space marine ships turn as well as any imperial ships. Don't fall into the tropes of, "if its fast it can't turn well," or "If the dudes are super strong they have to be super dumb." Marines break all the tropes, they are that bad-ass.

A basic frigate or destroyer is going to have just a few marines, perhaps a single squad. Cruisers generally have sufficient room for 1 company, and barges usually have up to 3 companies of marines. Since a chapter is likely to have only a handful of librarians, chaplains and the like, it is fair to say they should not be considered common aboard almost any ship other than barges currently carrying several companies. Compared to a normal ships retinue of thousands (even tens of thousands) of ratings I don't think its appropriate to say they have a "large number of astartes". I agree though boarding a ship with any amount of astartes is a very bad idea though.

Other than that you make all good points.