During 1935 the Director of Naval Construction produced several design studies showing various alternatives for what became the King George V class battleships. These designs were mainly for ships with "slow" and "fast" variations armed with 14 inch (35.6 cm) guns along with a few designs with 15 inch (38.1 cm) and 16 inch (40.6 cm) guns. In order to get these ships built as quickly as possible, the main gun caliber had to be chosen first and by September 1936 this choice had to made very soon so that work could begin. Meanwhile, on the Continent during the previous summer, the Germans had announced that their next class of battleships (Bismarck) would be armed with 38 cm (14.96") guns. The Italians in June 1935 announced that their new battleships (Littorio) would be armed with 15 inch (38.1 cm) guns. This was quickly followed by the French response that their new battleships (Richelieu) would be armed with 38 cm (14.96 inch) guns. Spurred by these developments and the need to select a gun caliber, the Sea Lords decided at a conference on 20 September 1935 that the first two post-treaty battleships would be armed with 15 inch (38.1 cm) guns.1 The resulting design was designated as 15C and was for a ship with nine 15"/45 (38.1 cm) guns in three triple turrets with a designed speed of 28.5 knots. However, shortly after this conference, the USA informed the British that they were willing to accept a 14 inch (35.6 cm) limitation on new construction, a limitation that the British greatly preferred. On 10 October 1935, First Sea Lord Chatfield wrote that the 15 inch (38.1 cm) designs were not well balanced in that they were fast but not well-armored. Friedman in "The British Battleship 1906 - 1946" (pg. 306) says that this "was probably a convenient way to live with a decision forced by the treaty conference." After this time, work on designs with 15 and 16 inch (38.1 and 40.6 cm) guns was discontinued and only 14 inch (35.6 cm) designs were pursued.
Construction of these new 15 inch (38.1 cm) guns would not have resembled the older wire-wound 15"/42 (38.1 cm) Mark I. Instead, they would have been of an "all steel" design similar to the 14"/45 (35.6 cm) Mark VII guns actually used on the King George V class. They were to have had a new-gun bore diameter of 14.985 inches (38.06 cm) in order to reduce clearance and thus increase accuracy life with 6crh shells.
Each of these new 15"/45 (38.1 cm) guns would have been about 3 tons (3.1 mt) lighter than the old 15"/42 (38.1 cm) Mark I, even though the new guns were three calibers longer than the old ones. It must be kept in mind that weight reduction was an important consideration for all of the Treaty limited warship designs of the 1920s - 1930s. A weight savings of 27 tons (28 mt) for nine guns, plus the accompanying reduction in ship's structure, would be considered quite significant for that reason.
It is possible that the new 15 inch (38.1 cm) triple mountings would have had the same interlock and other reliability problems found with the 14 inch (35.6 cm) mountings actually used on the King George V class battleships, as they shared similar design concepts.
The data that follows is necessarily of a sketchy nature, as little formal design work was done on this weapon and no prototypes were ever produced.
- ^Taken from King George V Cover No. 1, Folio 50. According to "The British Battleship 1906 - 1946," this is the only reference to the conference in this Cover.
| Designation | 15"/45 (38.1 cm) Mark II |
|---|---|
| Ship Class Used On | Proposed for the King George V class |
| Date Of Design | 1935 |
| Date In Service | Not produced |
| Gun Weight | 97 tons (98.6 mt) |
| Gun Length oa | 697 in (17.704 m) |
| Bore Length | 675.0 in (17.145 m) |
| Rifling Length | N/A |
| Grooves | N/A |
| Lands | N/A |
| Twist | N/A |
| Chamber Volume | N/A |
| Rate Of Fire | 2 rounds per minute |
| Type | Bag |
|---|---|
| Projectile Types and Weights 1a 2a | APC Mark XXIIb (6crh) - 1,938 lbs. (879 kg)
HE Mark VIIIb (6crh) - 1,938 lbs. (879 kg) |
| Bursting Charge | APC Mark XXIIb (6crh) - 48.5 lbs. (22.0 kg)
HE Mark VIIIb - 130 lbs. (59 kg) |
| Projectile Length | APC Mark XVIIb - 65.0 in (165.1 cm)
HE Mark VIIIb - 67.0 in (170.2 cm) |
| Propellant Charge | 430 lbs. (195 kg) SC 326 |
| Muzzle Velocity | APC 6crh - 2,510 fps (765 mps) |
| Working Pressure | N/A |
| Approximate Barrel Life | N/A |
| Ammunition stowage per gun | N/A, but probably 100 rounds |
| Range | Side Armor | Deck Armor |
|---|---|---|
| 17,200 yards (15,730 m) | 14.0" (356 mm) | 2.0" (52 mm) |
| 19,400 yards (17,740 m) | 13.0" (330 mm) | --- |
| 21,700 yards (19,840 m) | 12.0" (305 mm) | 3.0"(76 mm) |
| 24,500 yards (22,400 m) | 11.0" (279 mm) | --- |
| 26,000 yards (23,770 m) | --- | 4.0" (102 mm) |
| 28,000 yards (25,600 m) | 10.0" (254 mm) | --- |
| 29,500 yards (26,980 m) | --- | 5.0" (127 mm) |
| 32,500 yards (29,720 m) | --- | 6.0" (152 mm) |
This data is from "British Battleships of World War Two" and is presumably for a muzzle velocity of 2,510 fps (765 mps). This table assumes 90 degree inclination and is based upon theoretical calculations performed in 1935, not actual firing trials.
| Designation | Three-gun Turrets
King George V (3): N/A, but probably Mark III |
|---|---|
| Weight | N/A |
| Elevation | -3 (?) / +40 degrees |
| Rate of Elevation | N/A |
| Train | About -150 / +150 degrees |
| Rate of Train | N/A |
| Gun Recoil | N/A |
| Loading Angle | N/A, but probably +5 degrees |
Campbell, John
- "British Naval Guns 1880-1945 No 1" article in "Warship Volume V"
Friedman, Norman
- The British Battleship: 1906 - 1946
Raven, Alan and Roberts, John
- "British Battleships of World War Two
Tarrant, V.E.
- "King George V Class Battleships"
30 July 2006 - Benchmark
11 February 2012 - Updated to latest template
13 September 2016 - Converted to HTML 5 format
19 April 2019 - Reorganized notes, corrected MV error
10 May 2021 - Updated to latest template
29 September 2026 - Added detail on the decision to build 14" (35.6 cm) guns