Normandie Class Battleship - Development

Development

In December 1911, the French Navy's Technical Committee issued a report that examined the design of the Bretagne class that had been ordered for 1912. They concluded that the amidships gun turret was an unsatisfactory choice, based on previous experiences with blast damage on battleships from the 1880s. This position influenced the construction of the next class of dreadnought battleships, for which design work began shortly thereafter. The French Navy's design staff submitted the first draft of the new dreadnought design in February 1912. The size of French shipyard facilities significantly impacted the design. Length was limited to 172 meters (564 ft), breadth to 27.8 m (91 ft 2 in), and draft to approximately 8.8 m (29 ft). These dimensions limited the ship to a displacement of around 25,000 metric tons (25,000 long tons) and a speed of 20 to 21 knots (37 to 39 km/h; 23 to 24 mph), depending on the armament arrangement. The design staff advocated retaining the same armament and armor as the previous Bretagne class, and a top speed of 21 knots.

The design staff prepared another version that was armed with a main battery of sixteen 406 mm (16.0 in) guns in four quadruple turrets and had a top speed of 20 knots. The Technical department prepared two different designs for the propulsion system. Four direct drive steam turbines were proposed, as in the Bretagne class; the other option was a hybrid system that used a pair of direct drive turbines on the inner two propeller shafts, and two reciprocating steam engines on the outer shafts for low-speed cruising. The latter design was adopted for the new ships, as the all-turbine system was less fuel-efficient. The fifth ship, Béarn, however, was instead equipped with four sets of turbines. The armor layout of the Bretagne class was retained, and the full load draft fixed at no greater than 9 m (30 ft).

The next issue to be addressed was the main armament. The General Staff decided in March 1912 to retain the 34-centimeter (13 in) gun of the Bretagne class. They chose the new quadruple turret and advocated an armament of twelve guns in two quadruple and two double turrets. If this arrangement placed too much weight on the bow and stern, the arrangement of five twin turrets as in the Bretagne-class battleships would be substituted. In April 1912, the Naval Supreme Council accepted the latter design, unless the quadruple turret could be readied by the time construction was scheduled to begin. The armor layout of the Bretagne class was to be retained, though an increase in the thickness of the main belt was to be effected if possible.

The Technical Department prepared two new designs, A7, which incorporated the five twin turrets, and A7bis, which was armed with three quadruple turrets. The A7bis design was some 500 t (490 long tons; 550 short tons) lighter than the A7 design, and on 6 April, the Navy accepted a quadruple turret design submitted by Saint-Chamond. The secondary battery was initially to have comprised twenty-two 138.6 mm (5.46 in) guns, but by subtracting four guns, twelve 100 mm (3.9 in) guns could be added for the same weight. The 100 mm design was not completed by the time work was scheduled to begin, so the 138.6 mm gun was chosen. The Technical Department had initially proposed mounting the secondary guns in single and twin turrets, but it was determined that this arrangement was not flexible enough. Instead, they were mounted in casemates in eight groups of three guns.