Pugliese torpedo defense system
The Pugliese torpedo defense system was a passive system for reducing the damage caused by torpedoes to ships. It was developed in the early 1930s by the Italian chief designer Umberto Pugliese and was considered an innovative approach. It was installed in the new Italian battleships of the Littorio class and retrofitted on the older ships of the Conte-di-Cavour and Caio-Duilio classes during modernizations . In use, however, the system proved to be a counterproductive faulty design.
Mode of action
The system consisted of a large cylinder , which was filled with small watertight tubes and was installed in the outermost chamber of the ship's hull . According to the theory, the pressure wave generated by the explosion of a torpedo would destroy the large cylinder, using up its energy in the process. Most of the tubes contained in the cylinder were intended to remain intact and limit flooding of the affected compartment, as the water could not penetrate the tubes. In practice, however, the cylinder remained intact because the pressure wave of an explosion took the path of least resistance around the cylinder and was thus directed with full force onto the bulkhead on the inside of the chamber. However, this bulkhead was concave, as it had to be adapted to the shape of the cylinder in order to hold it in place. This is the most unfavorable form of withstanding a pressure wave, similar to a dam built the wrong way round, all energy is focused on one point, which leads to the breakage of the bulkhead and water ingress into the departments behind it. This "relaying" of the force of a torpedo explosion made the entire system worse than useless. While even the older battleships of all nations could usually cope with two or three torpedo hits, the Italians were in mortal danger from a single hit. Since the system could not be replaced without a massive conversion, the Italian battleships had to go into battle with this disadvantage throughout the war.
In addition, the system consumed a relatively large volume that could not be used otherwise. This was a disadvantage compared to conventional torpedo defense systems, which consisted of a mixture of empty and liquid-filled compartments one behind the other and where the liquid-filled compartments could be used as fuel bunkers (the chambers were filled with water when the fuel was used up).