How large could rangefinders become?

How large might naval rangefinders become in this scenario?

Their length has practical limits, but larger triple turrets provide more room; the ship's detailed arrangement determines what will fit.

Rangefinders have practical limits, but a triple 14-inch turret offers more room for a turret-mounted instrument. The larger mounting affects the ship's internal dimensions as well. In this reconstruction, Dreadnought would have a broader central core while remaining slightly narrower overall. The available space therefore depends on the mounting and hull arrangement, so no single maximum rangefinder length is proposed.