Why battleship turret count affected survivability

Why were four twin turrets considered more survivable than three triples when either layout retained six guns after losing a turret?

Four twins provided another independent mounting and more favourable protective spacing. Three guns could still form a salvo, so losing a second turret did not automatically end salvo fire.

Advocates of four twin turrets counted separate mountings as well as surviving guns. A four-turret ship could lose three turrets and still fire, while a three-turret ship lost its last mounting when all three had been disabled. Three guns could form a salvo, though six gave enough margin to lose two guns and continue with four. Twin mountings also allowed a narrower beam and citadel, leaving more distance between the barbettes and the outer hull as part of the protection scheme. Renown and Repulse could still use their two-gun after turret while retreating, although the result would be inaccurate fire rather than controlled salvos. A preference for four triple turrets takes the redundancy argument further, but protecting twelve guns would require a larger ship or creative accounting to fit the 35,000-ton treaty limit.