NothingNow
Banned
Yeah, agreed.I doubt anything really large will be built. Very poor return on one's investment. The likely limitations would be transitability via canals. What comes to mind in the Great War naval theater of the Adriatic Sea.
I was thinking at most like 14,000 tons displacement for any major warships, built on the same general plan as the Illinois or Maine-class (with allowances for differences in water density, and the weight of new equipment.) So, not very big for the era (120m long, with a 22m beam, drawing say 8-8.5m depending on the season.) In terms of performance, well, they're glorified floating batteries, and 14-15kts is plenty, and I'm doubtful they'd even need to be that fast in service.
They'd likely have just enough space for 4x12-15" guns in twin turrets, with 6-8" guns for the secondary battery and a mix of say a dozen 3" guns or QF 6pdr guns, a half-dozen QF 1pdr Pom-poms and a smattering of Maxim guns for defense, and average protection when built.
Lighter monitors would be too light to handle the weather, and too unprotected to handle their role, which would pretty much be shore bombardment, and siege work, with the odd duel against their counterparts. Everything else would be smaller, at less than say 3000tons displacement, mostly being Destroyers, minesweepers and Torpedo Boats, with the odd protected cruiser.