Musings On Battleship Armor & Protection

Musings On Battleship Armor & Protection Theoretically, it is not possible to sink the super dreadnought with pure artillery fire, regardless of whether the hits are horizontal or vertically placed.

Illustration of several armored ships from the 1880s, showing the degree of experimentation with armament arrangements

The mission-kill concept is far more important! This concept is defined as: An attack or damage inflicted by a weapon that does not destroy a military vehicle but results in it taking no further part in its intended mission.

For instance, the USS Washington had protection built around the “All or Nothing” concept. HMS Hood was entirely different regarding old armor (in layout and quality). 

Inside of the Armored Conning Tower on HMS Hood.
Date unknown.

There is no clear evidence as to why HMS Hood was destroyed. 

An aerial view of Hood in 1924: The two forward gun turrets are visible with their prominent rangefinders projecting from the rear of the turret. Behind the turret is the conning tower surmounted by the main fire-control director with its own rangefinder. The secondary director is mounted on the roof of the spotting top on the tripod foremast.

Barbettes and turrets on American battleships had these parts better protected than the German warship Bismarck. The forward conning tower on Bismarck had 350 mm (13.8 in) thick sides.

Bismarck’s forward conning tower.
Armor Protection Battleship Bismarck
Massachusetts’ armored conning tower, thickness: 16 inches of steel
Iowa-class conning tower

On Iowa-class battleships, the conning tower is a 439-millimetre (17.3 in) thick vertical armor-plated cylinder.

Kirishima’s APC 14 shell was unable to even slightly damage the No. 3, 16 inch sides of the turret barbette on the “South Dakota” at point blank range).

After turret of USS South Dakota BB-57 under construction.
Also, the belt armor on the American battleships was tilted by a significant angle, submerging it 90% underwater. 
North Carolina (BB-55) at sea during her shakedown cruise, circa April-May 1941. Note what appears to be false-bow-wave camouflage forward, possibly the result of wave action on her new paint. Courtesy of the Naval Historical Foundation, Maher Collection. U.S. Naval History and Heritage Command photograph. Catalog#: NH 83074 

During the war, N.C. class always operated at 44,795 ts, which was strictly adhered to during the voyage, due to tactical conditions (e.g. the height of the belt armor, which was to protrude only one meter above the waterline).

For instance, the vertical armor of the N.C. class was impenetrable for a ship like Bismarck at most of its range, with the belt around 90% underwater and inclined. In addition, the turrets, barbettes and Conning Tower armor were much thicker than Bismarck. 

USS North Carolina’s forward turrets and conning tower, May 1941

Broadside Weight

Broadside weight is incredibly important. 

Every hit produces a devastating effect with this amazing weight of APC projectiles (I hope you know the physics and how the impact force works), even without penetration (German turrets and barbettes were poorly protected, and could be penetrated at almost any range by 16″ Mark 8 APC projectiles). 

Broadside is about 11025 kg for the (N.C.) vs 6400 kg for (Bismarck, above).

Fitting-out stage of USS North Carolina, 17 April 1941

More guns result in more points of damage and — in some way — hit probability. Rate of fire is not so important. Especially at the first phase of combat because of the time between salvo and shell fall (splashes). 

In addition, when the “Washington’s” crew switched to continuous fire during the second battle of Guadalcanal. There they achieved a rate of fire equal to 2.7 per minute. 

Lastly, accuracy is primarily connected with the fire control system (not a gun itself), and it was superb on U.S. battleships and difficult to disable (unlike the German system, which could be disabled by a single hit).

USS North Carolina BB-55 and other warships firing on Okinawa. Note the projectiles in the upper left corner.

Written by Sławomir John Lipiecki : Analyst at United States Navy