How the Zara class saved weight for a battle-line role

The original requirement would not fit within 10,000 tons, so the designers cut weight across several systems. A raised forecastle and armour used for longitudinal strength reduced hull weight by 28 percent compared with the Trento class, while two-shaft machinery derived from the Condottieri light cruisers saved about 900 tons. The prospect of using the Zara class in, or even as, the battle line made torpedo tubes seem less useful, so they were omitted. The proposed 200 mm belt was reduced to 150 mm, showing how structure, machinery, protection, and combat role had to be traded against one another.