The battleship USS North Carolina

The battleship USS North Carolina

The construction of the USS North Carolina was preceded by a number of model tests carried out in a special Taylor deck. The results made it possible to determine the hull’s drag and the power plant needed to reach a speed of 27 knots at battle displacement as was estimated in the project. The tests led to the development of a relatively long hull (222.1 m) with slender theoretical lines which caused some problems while designing the ship’s interior. To reach high stability and to increase the level of underwater protection, the hull was equipped with up-to-date streamlined anti-torpedo bulges. These bulges were over 1.3 m wide on each side of the hull. Starting at a lower edge of the board armor, they extended as far as the triple bilge. As with older ships, the board armor was mounted to the side plating. To reduce the hydrodynamic drag, impacted by the board armor mounting and bulges, a large cast bow bulb was mounted.

North Carolina in 1943 with a Measure 21 camouflage. Bofors 40 mm quadruple mountings have already been installed. Visualization 3D: Stefan Dramiński

To avoid flooding of the bow deck, a special raked stem was designed (a slightly different design from older battleships) with widely open bow frames at the top. To ease the waterflow and to improve explosion durability of the shaft and propeller system two solid skegs were mounted at the stern. These were specially strengthened under-hull covers enclosing the end parts of the inner propeller shafts. There were two end pieces of outer drive shafts running on both sides of the skegs (one on each side). In their stream there were two solid rudder blades mounted with the area of 28.1 m2 extending over 36.5 degrees towards each of the boards. This resulted in the creation of a hull with very good naval characteristics at battle (44,795 ts) or full load displacement (46,800 ts). The battleship was navigable and easily manoeuvrable. At the maximum speed of about 27 knots a complete turning radius was merely 625 m, which made it one of the most easily manoeuvrable battleships in the world.
As with earlier US Navy battleships, the hull’s beam reached its maximum not far from bow and stern. This shape and construction enabled, amongst others, the ability to deepen the port and starboard anti-torpedo defence systems and its unification on particular frames8, and proved its worth over many years of service when the ship was at a sea for months in all possible weather conditions – even in hurricanes and typhoons. Deep draught (ca. 10.5 m at battle displacement) and a beam of 31.852 m at the waterline made the USS North Carolina a very stable artillery platform, a characteristic feature of the majority of American battleships.

North Carolina in 1944 with a Measure 32 camouflage. Mk-8 fire control radar antennas have been fitted on the main artillery directors and Mk-12 with Mk-22 antennas on the Mk-37 directors, SG surface search radars have been also installed on both masts. The CXAM-1 air & surface search radar antenna has been replaced by modern SK-2 antenna. Visualization 3D: Stefan Dramiński

The outer hull plating comprised sheets of special 19‑25 mm STS armored steel (homogenous), and 16-19 mm thick tensile strength (HTS) steel was used for underwater sections. There were six decks on the ship: main deck – bomb deck, second deck – main armored deck, third deck – plunging fire deck, two discontinuous platform decks (called first and second respectively), and a hold water deck. The distance between the decks, with the exception of plunging fire deck, reached 2.52 m (2.41 m at the edges, near the boards).
Innovative and compact turrets were designed for the USS North Carolina to enable the ship’s guns the widest possible firing angles. The vessel was a formidable weapons platform – with all of her main and subsidiary guns in action, the North Carolina could bring a full complement of 128 gun barrels to bear.
Along with the associated and modern opto-electronics this made cabin space very limited. There was a solid, elliptic main command post tower in the frontal part of the conning tower. The inside of the tower and the citadel were connected by a 406 mm (16”) communication tube. The main command post was partially built over by a navigation bridge with a wheelhouse. At the top of the bridge there was an Mk-37 sight director to control secondary artillery fire (as well as main artillery if need be). Unlike other types of American battleships, the bridge was not paned. There was only a row of slightly bigger than usual portholes, with special steel plunging fire covers on the outside.