During 1935 the Director of Naval Construction produced several design studies showing various alternatives for what became the King George V class battleships. One of these, designated 15C, was for a design with nine 15"/45 (38.1 cm) guns in three triple turrets. This design was considered to be one of the best proposals for these ships, but Treaty restrictions prevented the use of guns larger than 14" (35.6 cm). For this reason, 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" (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" (38.1 cm) triple mountings would have had the same interlock and other reliability problems found with the 14" (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.
| 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 1 2 | 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 |
"British Naval Guns 1880-1945 No 1" article by John Campbell in "Warship Volume V"
"British Battleships of World War Two" by Alan Raven and John Roberts
"King George V Class Battleships" by V.E. Tarrant
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