Would about 66,000 tons make HMS Incomparable practical?
Short answerIt would help, but a ship the Royal Navy actually built would more likely be a roughly 50,000-ton scaled-up Renown than Fisher's full proposal.
NotesFisher's aspiration differed from what Royal Navy constructors were likely to approve. Renown and Repulse provide the more realistic family resemblance, with high speed and battlecruiser protection priorities. A much larger hull would be needed for Incomparable's heavy armament. Raising displacement to 66,000 tons makes the paper concept easier to realize. A ship the Navy actually ordered would probably be a roughly 50,000-ton scaled-up Renown instead.