Principe di Carignano-class ironclad

The Principe di Carignano class was a group of three ironclad warships built for the Italian Regia Marina (Royal Navy) in the 1860s. The class comprised the ships ITALIAN IRONCLAD Principe di Carignano, ITALIAN IRONCLAD Messina, and ITALIAN IRONCLAD Conte Verde.

Design
The first two vessels of the Principe di Carignano class were initially ordered as steam frigates by the Sardinian Navy shortly before the unification of Italy. While they were on the stocks, the Regia Marina (Royal Navy) of the newly-formed Kingdom of Italy decided to convert the ships into ironclads. A third ship, ITALIAN FRIGATE Principe Umberto, was too far advanced in her construction to allow for conversion, and so she was completed as a wooden vessel. These ships had been designed by Inps. Eng. Felice Mattei. A fourth ship, Conte Verde, was built to a modified design created by Inps. Eng. Giuseppe De Luca. These ships came as part of a major naval expansion program that was designed to prepare a fleet of ironclad warships capable of defeating the Austrian Navy. Italy considered the Austrian Empire to be its main rival, since it controlled predominantly Italian areas, including Venice.

General characteristics and machinery
The ships of the Principe di Carignano class varied slightly in their dimensions. Principe de Carignano was 72.98 m long between perpendiculars, with a beam of 15.1 m and an average draft of 7.18 m. She displaced 3446 MT normally and up to 3912 MT at full load. The second ship, Messina, was 72.8 m between perpendiculars; she had a beam of 15.1 m and an average draft of 7.27 m. At normal loading, she displaced 3868 MT, and she reached 4245 MT with a full load. Conte Verde was 73.7 m long between perpendiculars and her beam was 15.3 m. She had a draft of 6.5 m, and displaced 3514 MT normally and up to 3866 MT at full load. The ships had a crew of 572.

Their propulsion system consisted of one single-expansion steam engine that drove a single screw propeller, with steam supplied by six coal-fired, cylindrical fire-tube boilers. The boilers were trunked into a single funnel. Their engines produced a top speed of 10.2 to 11.4 kn, with Conte Verde being the fastest member of the class, from 1968 ihp. They could steam for about 1200 nmi at a speed of 10 kn. To supplement her steam engine, the ship was barquentine-rigged with three masts.

Armament and armor
The Principe di Carignano-class ships were broadside ironclads; the lead ship was armed with a main battery of ten 72-pounder 8 in guns and twelve 164 mm rifled muzzle-loading guns Messina and Conte Verde instead carried four 8 in guns and eighteen 164 mm guns. The ships were equipped with a spur-shaped ram at the bow. In 1870, the ships' armament was revised; Principe di Carignano retained four of her 8 in guns, with the other four being replaced by 164 mm guns. Messina lost ten of her 164 mm guns and gained a pair of 10 in guns, while Conte Verde was reequipped with six 10 in guns and one 8 in gun.

The first two ships' hulls were sheathed with wrought iron armor that was 4.75 in thick. Unlike her two sisters, Conte Verde did not have complete iron armor on her sides. She instead had wrought iron armor that covered only parts of her bow and stern. The rest of the ship received traditional timber armor.