Courbet and Bretagne had already adopted turbines, but Normandie combined turbines with vertical triple-expansion engines in pursuit of efficiency. France's main naval opponent was nearby, weakening the case for accepting that complexity to improve long-distance operation. American experiments at least assigned the different propulsion systems to separate ships; the French arrangement required one crew to operate both. Vertical triple-expansion engines also occupied considerable height inside the hull. Their dimensions affected machinery spaces, protection, and turret placement, adding a design cost beyond the proposed fuel saving.
Notable Point · 12:08-13:50
Normandie's mixed engines complicated training and protection
Combining turbines and vertical triple-expansion engines required two operating skills and a machinery layout that accommodated the taller engines.