BB-49 South Dakota Class

Six South Dakota (BB-49) class battleships were authorized in 1918-19 to be built to an enlarged Colorado (BB-45) class design. Five ships were laid down in 1920 and the sixth in 1921. All work was suspended on 8 February 1922, when they were between 11% and 38% completed, in accordance with the Washington Naval Treaty of 1920. Their construction was cancelled on 17 August 1922. All six remained on the building ways until October-November 1923, when they were sold for scrapping.

The six battleships of the South Dakota class were slower but more heavily armed and armored contemporaries of the Lexington class battle cruisers. Had they been built, they would have been the most powerful battleships in the US fleet at the onset of World War Two. These would encorporate an enormous gun armament of twelve sixteen inch guns, secondary battery of sixteen six inch guns, as well as anti-aircraft armament.

Like the Lexington class, the South Dakota's were large ships, with a designed displacement nearly a third greater than their immediate predecessors. These were classic U.S. Navy battleships, well protected against gunfire and torpedoes, heavily armed, but relatively slow, intended to prevail in a big-gun slugging match with an enemy battleline. Their main battery represented a fifty-percent increase in number of guns (twelve versus eight), and these 16" guns were of a somewhat more powerful type than those fitted to previous U.S. battleships. After cancellation of their ships, some of these weapons were employed for seacoast defense. Armor and boilers from the South Dakota class were also recycled for use in modernizing older battleships.

In considering the military features of battleship design, the war between guns and armor was ever present. The quality of armor has steadily improved, and this ordinarily would permit reducing the relative weight of this defensive element But concurrently with the improvement in quality of armor has come great increase in the power of ordnance. So that instead of the thickness of armor and percentage of total weight allotted to that element undergoing a reduction there has been a tendency toward increase. Moreover, this increase in protective features is by no means confined to side armor.

Possible under-water damage from torpedo and mine and the new dangers arising from overhead aerial attack, in addition to the greater vulnerability of deck armor to damage from gun fire due to increased angles of fall of projectiles fired from great ranges, have necessitated a very great increase in deck and internal bulkhead armor. The necessity for providing against vessels being put out of action or sunk through damage due to attack by torpedoes and mines has also necessitated the provision of large side compartments throughout the vital portions of the length of the ship.

These compartments are so arranged as to permit of a very considerable absorption of the explosive effect due to shells which explode in- the interior after penetrating the side of the vessel. In some ships already built or whose construction was considerably advanced at the time fo the Great War, the provision of additional explosive compartments for protection against submarine and mine attack took the form of "bulges."

There were those, however, who contend that the damage arising from such mine and torpedo attacks can best be guarded upainst by protecting the vital portions of the vessel by increased wing compartmental subdivisions provided for in the origjnal design of the vessel. This, of course, necessitated increase of beam, but no greater increase than is necessary through the addition of extraneous compartments, as in the case of vessels with "bulges."

As indicating the serious increase in beam necessitated by the provision of such special explosive compartments, it may be noted that American battleships designed during the Great War were given a beam only limited by the capacity to pass such a vessel through the Panama Canal locks; so that, in the United States navy, from the Oregon of 1890, with a beam of little more than 69 feet, there was developed the South Dakota class of 1919, whose beam was 106 feet.

There are several serious physical limitations which had to be recognized in battleship development. Among the most important of these is the comparatively shallow depth of many important harbors, both naval and commercial. There is also the limitation imposed by the sizes of existing dry docks and the locks of great inter-oceanic canals. It is essential, therefore, to limit the draft to as small an amount as practicable, not only with respect to entry into such harbors under normal conditions, but also to permit entry under damaged conditions and to permit utilization of existing docks and inter-oceanic canal locks.

In developing the designs of battleships and other exceptionally large war vessels, the ship designer was confronted with many conflicting requirements. If he permitted himself to overdevelop any one of the most important characteristics, he invariably did so at the expense of some other characteristic which may be considered of less importance by some and yet by others may be considered as of equal or greater importance.

In no particular has the development of battleship design advanced to a greater degree than in the element of offensive power. Thus, it will be seen that the main battery of the Oregon class, which was considered a very heavy primary battery for that date, was four 13-inch guns of 35 calibres. Subsequently the 12-inch puns of greater length was adopted for the main battery of United States battleships and up to and including the Arkansas class, the heaviest gun of the main battery for United Slates battleships was the 12-inch,, 5O-calibre gun. The primary battery of the South Dakota class, however, was to consist of twelve 16-inch, 5O-calibre guns, mounted in four centre-line turrets, thus making three guns in each turret.

It is interesting to note that the general features of turret location and relative heights of barbettes of the South Dakota class are identical with those of the South Carolina class - the first of the modern all-big-gun ships of the United States navy. There is a very important difference in the battery power, however, in that the South Carolina class have only two 12-inch guns in each turret, while, in the South Dakota class, there are three 16-inch guns in each turret. As the muzzle energy of the 12-inch, 45-calibre gun of the South Carolina is approximately 49,000 foot-tons and the muzzle energy of tlie 16-inch, 5O-calibre gun of the South Dakota is approximately 114,000 foot-tons, it will be observed that the energy of broadside o[ the main battery of the South Dakota class is three and one-half times that of the main battery of the South Carolina class.