The tradeoffs in 12,500- and 15,000-ton treaty cruisers

How would the treaty era change with 12,500-ton light cruisers and 15,000-ton heavy cruisers armed up to 12 inches?

Light cruisers would gain very large 6-inch batteries, but heavy cruisers would face severe balance problems and the treaty's total tonnage ratios would also need revision.

A 12,500-ton light-cruiser ceiling gives designers enough room for very heavy 6-inch batteries, potentially fifteen guns. The 15,000-ton heavy category is less straightforward because 12-inch guns and their mountings consume displacement rapidly. Designers would have to choose between a few long-range heavy weapons and more numerous faster-firing guns. Existing aggregate tonnage ratios could not simply remain unchanged because treaty totals were calculated from the expected number and size of ships. The proposal therefore changes both individual designs and the fleet arithmetic behind them.