Béarn's inner shafts used turbines while the outer pair retained vertical triple-expansion engines. The mixed plant bought economical cruising range but required spares and expertise for two propulsion systems. Its roughly 21.5-knot maximum also undercut the carrier's ability to generate wind over the deck in the relatively calm Mediterranean. A 1934-35 proposal for new turbines and boilers promised about 23.4 knots, falling to 22.3 knots with torpedo bulges. Her later survival owed more to escort and aircraft-transport work than to fitness for first-line carrier operations.
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Béarn traded flight speed for mixed propulsion
Béarn's combination of turbines and triple-expansion engines delivered range but limited the carrier to about 21.5 knots when deck wind was vital to early aircraft.