The ships displaced 5,121 tonnes (5,040 long tons) and had a draught of 8.45 metres (27 ft 9 in) at deep load.

[1] The primary difference between Napoléon and the Algésiras class was that the boilers of the latter ships were moved forward of the engines.

They were powered by a pair of two-cylinder horizontal-return connecting-rod steam engines, also designed by Dupuy de Lôme, that drove the single propeller shaft using steam provided by eight boilers.

During her sea trials, Algésiras reached a sustained speed of 13 knots (24 km/h; 15 mph).

[1] In 1859, she took part in the blockade of Venice and various operations in the Mediterranean during the Second Italian War of Independence.