I'm confused. See, I get where Kasaltka is coming from, I just don't understand why this is a debate.
Citation 1: "[Because torpedos], on any vessel of Grand Cruiser size and smaller, torpedoes may only fire into the Fore arc, regardless of where the weapon Component is located." BFK page 6.
Citation 2: Rogue Trader core rulebook page 219: "Prow weapons on light cruisers, cruisers, or larger vessels may fire to the fore, port and starboard." Also, "Keel weapons may fire in any direction."
Citation 3: BFK- torpedo tubes can only be mounted in Prow or Keel slots, BFK page 37.
IF we assume that RT is a restrictive system (i.e., you cannot do anything unless the rules say you can do the thing) then Citation 3 grants permission for Battleships with Prow or Keel slots to mount torpedo tubes, Citation 2 grants permissions for those torpedoes to be fired as appropriate for those slots, and Citation 1 does not apply because the vessel is not "Grand Cruiser size or smaller."
IF we assume that RT is a permissive system (i.e. you can do anything the rules don't specifically restrict) then permission is inherent to the permissive system, Citation 3 restricts where the torpedoes may be mounted, Citation 2 restricts which arcs they may be fired in, and Citation 1, itself restricted to vessels of Grand Cruiser size or smaller, does not apply.
THEREFORE, RAW, in Rogue Trader, a battleship may fire torpedoes in whatever direction is appropriate for the slot the torpedo tubes are mounted in, regardless of the rules put forth in Battlefleet Gothic- because BfG is not Rogue Trader. Quod erat demonstratandum.
In your game, do as you like- I know I do- but, as we are not in the House Rules subforum, let's keep it RAW, yes? Unless there are errata or other rules you would like to cite to refute?
Edited by Annaamarth, 06 May 2014 - 02:01 PM.