The Joffre class was expected to carry roughly forty aircraft and receive significant, though not massive, protection. The strength deck between the upper and lower hangars was probably the armoured deck, although translated sources leave some uncertainty. Eight water-tube boilers would supply two geared steam turbines driving only two shafts. Reaching about 33.5 knots through that arrangement required a large concentration of power on each shaft. At 18,000 tons standard displacement, the ship would be roughly four to five thousand tons lighter than Ark Royal or the Illustrious class. The figures define a fast, compact carrier whose machinery and protection choices were ambitious for its size.
Chapter · 24:55-26:24
High power supported a forty-aircraft light carrier
The planned carrier combined about forty aircraft, uncertain but meaningful protection, and 33.5-knot speed on an 18,000-ton hull.