Otherwise it says for multiple ship bording action, that there always has to be an attacking player, which has to distribute inflicted damage points among the attacking ships. That let me assume that the turrets are always included.
ie imagine an Ork KK is being boarded by 2 SM SC's. The SM player looses the boarding action and took 2 damage points which he distributed amongst both SC's, so each get's one damage point. In the Ork players turn the fighting continues and he inflicts again 2 damage points to the SC's. It now would make more sense, if the Ork player has to distrubute the damage points amoung the SC's as he commands his Orks how to attack the enemy SC's and may focus his boarding attack on a single SC. So he should be able to inflict both damage points to a single SC rather than the SM player has to distribute them among his ships. This leads one to suppose, that the player, in which turn the boarding action continues, is the attacking player, so the other get's the turret bonus.
I think I remember I read somewhere, that a player may only defend against a boarding action during the enemy's turn.
What do you think?