Ark Royal and the Illustrious class historically used six boilers for three shafts. Four higher-pressure boilers could preserve redundancy while freeing volume and weight for torpedo protection or a longer hangar. For the armored carriers, even modest extra hangar and deck-parking capacity could raise the embarked group substantially, with the Royal Navy likely assigning much of the gain to fighters and torpedo-strike aircraft. The estimate for the larger wartime aircraft is 42 to 48 aboard an armored carrier, compared with the historical 36-aircraft combination.
Notable Point · 32:42-37:44
Carrier machinery savings become aircraft capacity
Fewer boilers could give Ark Royal better protection and let Illustrious-class carriers trade machinery weight for a longer hangar and a larger air group.