Why subdivision matters even when armor stops a shell

Would Hood still suffer damage from heavy shells that failed to penetrate her belt?

Yes; nonpenetrating hits still transmit shock, and her lighter subdivision would contain that damage less effectively than a battleship.

A follow-up asks whether Hood could suffer shock damage even when the belt kept a shell out. The answer is yes, and the same mechanism can affect a battleship. More extensive internal subdivision is judged to restrict the area over which that damage spreads. Hood's battlecruiser arrangement therefore matters alongside armor thickness. Clarke applies the same distinction to Vanguard, describing her as a fully armored battlecruiser because of her subdivision; that is his classification in this discussion.