This was quite possibly the best large-caliber naval gun ever developed by Britain and it was certainly one of the longest-lived of any nation, with the first ship-board firing taking place in 1915 and the last in 1954. The design of this weapon was largely based upon the 13.5"/45 (34.3 cm) Mark V and it was rushed into production, bypassing the normal - and lengthy - prototype stage. This shortened design cycle was approved by the Director of Naval Ordnance, Rear Admiral Archibald Moore, who staked his "professional existence" on its success. The reason for this rushed procedure was to allow what became the Queen Elizabeth class battleships to be armed with larger guns than would have otherwise been possible. Although their first warshots were for bombarding shore positions at Gallipoli in 1915, the value of these weapons was not truly shown until the Battle of Jutland (Skagerrak). In that battle, the British battleships with these guns were able to engage German battlecruisers at a range of 19,000 yards (17,400 m), which was beyond the maximum range of the guns on the German ships.
By the mid-1930s the Admiralty saw these guns as growing obsolete, as other nations had developed more powerful weapons, capable of longer ranges and firing heavier projectiles. Along with this, the ships carrying these guns were approaching twenty years of service and starting to show signs of wearing out. Inhibited by treaty restrictions from replacing the battleships, the British instead sought to rectify the situation by initiating a "modernization" program whereby the ships had major overhauls performed and had their weapons upgraded. There were two significant improvements made to these guns during the modernizations: 1) The upper elevation limit of the mountings was increased from 20 degrees up to 30 degrees, which raised their maximum range with 4crh projectiles from 23,700 yards up to 29,000 yards (21,670 m to 26,520 m), and 2) The projectiles were redesigned to add a more streamlined ballistic cap (6crh), which increased the range still further to about 32,000 yards (29,260 m) at 30 degrees elevation. Thanks to these modifications, in July 1940 HMS Warspite made one of the longest hits ever scored by a naval gun on an enemy ship when she struck the Italian battleship Guilio Cesare at approximately 26,000 yards (23,770 m).
The rate at which these ships could be modernized was limited and by the start of World War II Malaya, Barham, Repulse and the five Royal Sovereign class battleships had not yet been upgraded. Royal Oak, Barham and Repulse were sunk early in the war, but the remaining unmodernized ships were given a "Super Charge" which consisted of the largest possible propellant charge that the guns and mountings could safely handle. These were issued starting in late 1941 and at the maximum elevation of 20 degrees allowed a range of 28,700 yards (26,240 m). However, from a study of the records, it would appear that no ship ever fired a shot using Super Charges, although they were used by the coastal artillery at Dover. Super Charges were not issued to ships with 30 degree mountings as the increased barrel wear and mounting stress was not considered to be acceptable. For this reason, sources which quote HMS Vanguard as having gun ranges in excess of 32,000 yards (29,260 m) are somewhat misleading, as such a range would have required the use of super charges, which she never carried.
In addition to the ship-board guns, there were also four guns (one source says five) used as coastal artillery at Singapore and a further two mounted at Wanstone near Dover.
Constructed of tapered inner A tube, A tube, full-length multi-start wire, B tube, overlapping jacket and breech ring. Used a Welin breech operated by hydraulic Vickers "pure-coupled" mechanism. A total of 186 guns, including two prototypes, and 58 turrets were manufactured between 1912 and 1918.
The second prototype gun, E597, was to a considerably different construction, having a full-length jacket, no B tube and an Elswick three-motion short arm breech mechanism which considerably reduced "slam." This gun suffered a failed A tube during proof testing. Had this gun not failed, the Elswick breech mechanism probably would have been used on all production guns.
Note: It is often asked if the British ever planned to use these guns for the King George V battleships of World War II. The answer is that they did not, but there was some investigation into using a new design, the "all steel" 15"/45 (38.1 cm) Mark II gun.
|Designation||15-inch Mark I|
|Ship Class Used On||Battleships: Queen Elizabeth, Royal Sovereign and Vanguard classes
Battlecruisers: Glorious, Repulse and Hood classes
Monitors: Marshal Soult, Erebus and Roberts classes
|Date Of Design||1912|
|Date In Service||1915|
|Gun Weight||224,000 lbs. (101,605 kg) including breech mechanism|
|Gun Length oa||650.4 in (16.520 m)|
|Bore Length||630.0 in (16.002 m)
|Rifling Length||516.3 in (13.115 m)|
|Grooves||(76) 0.1245 in D x 0.445 in W (2.16 x 11.30 mm)|
|Lands||0.175 in (4.445 mm)|
|Twist||Uniform RH 1 in 30|
|Chamber Volume||30,650 in3 (502.3 dm3)|
|Rate Of Fire
see Note 1
|2 rounds per minute|
- The nominal firing cycle for the Mark I and Mark I* mountings was 36 seconds, but 30.2 seconds was achieved on 1 October 1917 by one ship. The Mark II mountings used on Hood had a nominal firing cycle of 32 seconds.
- The following excerpt is taken from "Progress in Gunnery Material,
1921" ADM 186/251:
32. Comparison between British and German Gun Designs
(a) The design of German 38 cm, 42.4 calibre Naval gun mounted in “Baden” has been carefully investigated and compared with that of the British 15 in. Mark I 42 calibre gun.
(b) The main points of difference between this [German] design and British designs are as follows:
(i) The gun is not relinable.
(ii) Factors of safety are lower. In calculating the strength of the gun at any point, the Germans allow the steel to be stressed much nearer to its elastic limit that we do in our designs, also the figure of elastic limit which they take for purposes of calculation is higher than ours. The gun is not serviceable with barrel split.
(iii) The gun is a Q.F., which permits of radical differences in construction from those necessary at the breech end of a B.L. gun.
(iv) All-steel construction as against wired type.
(v) Much smaller chamber (Capacity 18,000 cu. in. as compared to our 30,590.)
[Comments on the above items](c) As regards (i), the life of our guns (about 325 E.F.C.) is apparently considerably less than that of German heavy guns owing to their use of cooler propellant. They evidently considered that the life of their guns was long enough to justify the simpler lighter design which is possible when relining is not intended. Experiments with propellants generally similar to the German are in hand, but some time must elapse before any can be adopted to replace cordite M.D. in the Service. Until then it is considered that we should certainly continue to design our guns for relining.
The effect generally of (i), (ii) and (v) is to lighten the gun considerably.
(iii) is a matter of general policy ; there are reasons both for and against Q.F. guns of this calibre
(iv) The advantages of all-steel versus wire-wound guns have been the subject of discussion for a great many years, and opinions still differ as to which is better than the other from point of view of strength and ballistics ; more recently, however, it has been considered probable that the smaller droop and greater rigidity of the all-steel type may be a very important factor in effect on accuracy. The German gun is noticeably stiff in the region of the centre of gravity, making for small droop and whip ; this is undoubtedly a good point.
(d) As regards (ii), apparently German designers placed greater reliance on their steel forgings than we do on ours, and consequently stressed them much more highly. In all large steel forgings there is always a certain factor of uncertainty which we have allowed for and the Germans have been content to neglect. This is not confined to gun construction, but it is to be found throughout British engineering practice generally. The high factors of safety used in this country are considered to be partly due to the above and partly to caution, which may have been brought about by a few failures of guns in the past caused by faulty building or poor steel, also because there has been no special demand for light gun. We now call for a factor of safety of 1.5 over the chamber and of 2 forward before the steel is stressed up to a figure well below the specification yield point (20 tons as against the German 27). Consequently according to German ideas our factor of safety is 2 or 2.7.
The possibility of reducing the factors of safety in our gun designs has been the subject of discussion recently, and trials to test whether they are unduly great have been arranged for. Doubtless some reduction will now be possible in view of the great advance in machining operations and steel treatment made of late years, but improvements materially affecting our designs can only be adopted gradually. It is confidently anticipated that the forgings for the 16 in. designs will be much superior to what we have had in the past and fully equal to the German, the chief advance being in improvement in elastic limit and resistance to shock, which latter as evidently been specially attended to by German steel makers and is now provided for in our specifications for steel forgings.
The effect of these two points (lower factor of safety and high stress in the steel in the German design) is very marked over the chase with consequent reduction in weight and therefore decrease in the droop – a point already referred to in para. (b).
(e) As regards (iii), a movement between breech bush and inner tubes in a Q.F. gun with cartridge case is of much less importance than with B.L. gun and obturator pad in maintaining an effective seal, and this has permitted the longitudinal stresses being taken direct by the jacket, the breech bush screwing into this instead of into the A tube as in our designs. This simplifies design and manufacture. It has also permitted the use of short hoops in lieu of a long B tube, a form of construction that offers many advantages in accuracy of building shrinkage, though at the same time providing less longitudinal strength, which is poor in the German design according to our ideas.
The fact that the Germans accepted this longitudinal weakness shows that they had great confidence in the workmanship and skill of their gunmakers, as good results depended entirely on these. Our guns are undoubtedly easier to build and are so strong circumferentially due to the wire that the accuracy in building shrinkages, necessary in the German design[,] has not been called for.
(f) As regards (iv), steel and wire construction will be tried out in the trial 16 in. designs, also in trial 6 in. guns to be manufactured this year.
(g) As regards (v), the small size of chamber is not suitable for a solid cord propellant which we have hitherto adhered to. The question of adopting a tubular propellant [may be resolved as] various experiments are in progress.
The opinion is now held that the tubular shape makes for higher M.V. but reduced accuracy as regards mean differences in M.V.
It is more difficult to manufacture to accurate dimensions than cord or oval. Also, with a propellant such as M.D. cordite which has a volatile solvent (acetone) there would be less uniformity of stick than is obtainable with a propellant (like the German) with non-volatile solvent. Ardeer cordite* has a non-volatile solvent. Again, owing to its form, a tubular propellant is inherently more susceptible to the influence of variations in ballistic conditions, and thus, though actual wear may be less, loss of velocity for a fewer number of rounds may be greater.
It is, however, one of the many things that requires further investigation before we can be in a position to decide finally what to adopt in the future. It is quite certain that we shall be able to improve on cordite M.D.
(h) Apparently the Germans consider it unnecessary to fire proof rounds in testing guns for supply, and, to take this gun as an example, this certainly permitted them to cut down factors of safety, and therefore weight.
(i) Summarising, the main lessons to be learnt from study of the German design are :-
(i) The possibility of reduced factors of safety being introduced into our designs, especially towards the muzzle.The trial 16 in. guns and experiments in hand on other guns will test some of these points, but the trial guns have chases with a large factor of safety and the droop is therefore not the smallest obtainable.
(ii) The reduction of droop by (i) combined by the use of all-steel construction with a view to obtaining greater rigidity and consequently improved accuracy. At the same time distance of centre of gravity of gun from breech end would probably be decreased, and this would be advantageous as affecting diameter of barbette and size of mounting generally.
(iii) The need for taking advantage of manufacturing progress and greater knowledge obtained by experience in ordering trial guns of new designs from time to time, so that when new guns are required in supply they can be ordered to the most up-to-date designs. Unless this is done, our gun designers cannot acquire confidence in their designs nor can the gun makers gain experience in building.
(iv) The necessity for constantly revising our specifications to obtain the best possible gun steel, and for ensuring by strict inspection during manufacture, that specifications are adhered to and that the workmanship is of the highest standard.
(j) It may be of interest to mention here that the trial 16 in. gun under manufacture by E.O.C. weighs practically the same as a gun of similar calibre that has been designed working to German figures and methods. It will be clear, therefore, that a good deal has been done already towards reducing weight ; but, although this is very desirable, it can certainly be overdone, and if the gun is not sufficiently stiff, its accuracy will be less good than one where weight has been subordinated all through to gunnery considerations. There is no doubt at all as to the importance of stiffness in a gun.
(k) It is the intention to build, next year, a 6 in. gun to the German design, so far as this can be done without adopting the Q.F. principle, and to try this gun against our guns of similar calibre.
* "Ardeer" was a large cordite factory
located in Ayrshire, Scotland and was involved in the development of new
propellants following World War I. For some interesting historical
information, please see The
Great Dynamite Factory.
|Projectile Types and Weights||World War I Period
APC Mark Ia (4crh) - 1,920 lbs. (871 kg)
APC Mark IIIa (4crh - Greenboy) - 1,910 lbs. (866.4 kg)
APC Mark Va (4crh - post World War I) - 1,917 lbs. (869.5 kg)
CPC 4crh - 1,920 lbs. (871 kg)
HE 4crh - 1,920 lbs. (871 kg)
HE 8crh - 1,965 lbs. (891 kg)
Shrapnel 4crh - 1,920 lbs. (871 kg)
Inter-war to World War II Period
(see Note 3)
|APC Mark Ia - 60.5 lbs. (27.4 kg) Lyddite
APC Mark IIIa - 45.3 lbs. (20.5 kg) Shellite
APC Mark Va - 45.3 lbs. (20.5 kg) Shellite
CPC - 129.3 lbs. (58.6 kg) Originally gunpowder, later TNT
HE 4crh - 216.5 - 224.0 lbs. (98.2 - 101.6 kg) Lyddite
HE 8crh - 224.0 lbs. (101.6 kg) Lyddite
Shrapnel - 13,700 1.75 oz (49.6 gm) lead-alloy balls
APC Mark XIIa - 48.5 lbs. (22.0 kg) Shellite
(see Note 2)
|APC Mark Ia - 54.5 in (138.4 cm)
APC Mark IIIa - 55.9 in (142.0 cm)
APC Mark Va - 55.9 in (142.0 cm)
CPC - 63.3 in (160.8 cm)
HE 4crh - 63.9 in (162.3 cm)
HE 8crh - N/A
Shrapnel - about 63.9 in (162.3 cm)
APC Mark XIIa - 55.9 in (142.0 cm)
|Propellant Charge||World War I: 428 lbs. (194 kg) MD45
After 1927 (standard charge): 432 lbs. (196 kg) SC 280
Super charge: 490 lbs. (222.2 kg) SC 300
(see Note 1)
|World War I
APC 4crh - 2,467 fps (752 mps)
|Working Pressure||MD and SC standard charge: 20 tons/in2 (3,150 kg/cm2)
Super Charge: 23 tons/in2 (3,620 kg/cm2)
|Approximate Barrel Life
(see Note 9)
|Ammunition stowage per gun
(see Note 5)
|Queen Elizabeth, Royal Sovereign and Vanguard classes: 100 rounds
Renown, Courageous and Hood classes: 120 rounds
Marshall Soult and Erebus: 100 rounds
Abercrombie and Roberts: 110 rounds
- There are disagreements between the sources listed below as to the muzzle velocity of these guns, which I suspect has to do with whether they use "new gun" or "average gun" figures. In the table above, I have chosen to use those muzzle velocity figures given in "Warship Volume V" for MD charges and those muzzle velocity figures given in "Naval Weapons of World War Two" for standard SC charges and for SC super charges. These are "new gun" figures, while the muzzle velocities given in the range tables below represent "average gun" figures and are taken from the official British range tables.
- The 4crh projectiles are more properly defined as 3.05/4crh. The 6crh projectiles are more properly defined as 5/10crh. See the Naval Technology Board essay, Calculating crh for further information. The 8crh projectiles were only supplied to Monitors and were introduced in 1918. These had an extra ballistic cap which gave them an additional 3,000 yards (2,730 m) of range over the standard 4crh HE projectiles. As a guess, the 8crh projectiles would have been at least 75 inches (190 cm) long, which would have required specialized handling gear.
- The well-known failure of British APC to penetrate German armor at Jutland (Skagerrak) was partly due to the sensitive nature of the Lyddite bursters which caused many shells to explode immediately following impact on the target. In the next few years a new burster called "Shellite" was developed which was a mixture of Lyddite and dinitrophenol (DNP), which was a much weaker and insensitive explosive. Originally, a mixture of 50/50 was used, but this gave insufficient fragmentation. Tests with 60% Lyddite and 40% DNP bursters were satisfactory, and it was this combination that was used for the first "Greenboy" APC projectiles issued beginning in 1918. Soon after the end of the war, it was determined that a 70/30 mixture would give improved fragmentation while maintaining an adequate margin against premature explosions. This mixture was used for all subsequent British APC projectiles of this caliber.
- The 6crh projectile was introduced in 1938. Originally, these new projectiles were limited to Warspite, Renown, Valiant and Queen Elizabeth. In other words, they were only issued to those ships with the upgraded Mark I/N or Mark I*/N mountings. This was apparently because the projectile handling equipment on the non-modernized ships could not accommodate the longer 6crh shell. Those ships that did not get this handling system upgrade (including HMS Hood) could not use these longer shells, so in their place they were given projectiles with the same shell body and cap but fitted with a shorter 4crh windscreen similar to the older APC Mark Va -- the shells were heavier due to a thicker AP cap and a blunter pointed nose under it (1.3crh), but they were the same length as the earlier Mark Va shells. Following a refit in mid-1940, Barham was outfitted with 6crh projectiles and the surviving ships were modified to use them from late-1941 to mid-1943. Hood, Royal Oak and Repulse apparently never carried 6crh projectiles, as they were all sunk before the necessary modifications could take place.
- Outfits for all battleships and Renown were originally limited to APC. The Renown class later carried 60 APC and 60 CPC, then 72 APC, 24 CPC and 24 HE and at the end of the war carried carried 84 APC and 36 CPC per gun. The Courageous class were originally designed for 80 rounds per gun but this was increased to 120 rounds following the Falklands battle, where ammunition expenditure was very heavy. The Courageous class initially carried 72 APC, 24 CPC and 24 HE but all HE was replaced by mid-1917 and the immediate post-war outfit was 36 APC and 84 CPC per gun. The Royal Sovereign class may have carried 104 rounds per gun as commissioned. In the 1920s, 6 shrapnel rounds per gun were added to most battleships while the outfit for Renown was changed to 96 APC, 24 CPC and 6 shrapnel rounds per gun plus a total of 70 practice rounds. As completed, Hood had an outfit of 289 CPC, 672 APC, 30 shrapnel (stored only in the bow shell rooms) and 82 practice rounds. After her 1929-1931 refit, she carried 160 CPC (TNT burster), 640 APC (Shellite burster), 48 shrapnel and 96 practice rounds. The three follow-on "Admiral" class battlecruisers would have had their outfits reduced to 110 rounds per gun for "A" and "B" turrets and to 100 rounds for "X" and "Y" turrets due to changes in arrangement of the magazines and shell rooms - see the Mount / Turret Notes below for additional information. In the latter years of World War II, surviving ships replaced five APC rounds per gun with HE unless they were assigned to bombardment missions, in which case the proportion of HE was greatly increased. Outfits for monitors during World War I was 10 CPC and 90 HE per gun while during World War II it was 30 to 60 APC or CPC and the balance HE. Monitors usually carried 8 practice shells per gun. HMS Vanguard carried 95 APC, 5 HE and 9 practice shells per gun from the time of her completion up until she was converted to "Royal Yacht" duties in 1947, after which time she rarely carried any main gun ammunition at all.
- Propellant was in quarters for all charge types. Super charges were supplied at the rate of twenty per gun to ships with 20 degree mountings.
- During World War II "K" shell Mark Ib
K T was introduced which contained dyes for coloring the shell splashes.
These shells also had a small fuze and burster to disperse the dye.
These additions increased the APC weight to 1,944 lbs. (882 kg).
Active ships had the following colors listed in a 20 June 1946 Fleet Order:
Queen Elizabeth: Red
- At the start of World War I, a CPC projectile cost about £65, HE £37 and a full charge £40. These prices almost doubled by the start of World War II.
- The life figure given above is for APC with full charges. HE was limited to 250 EFC as the longer body and greater longitudinal inertia could result in unsteady flight if the rifling was too worn. Erosion was greatly affected by the size of the charge, with a 3/4 charge causing only 1/4 of the erosion of a full charge. The 15" (38.1 cm) guns were usually condemned when the wear reached about 0.74" (1.9 cm) at a point one inch (2.54 cm) from the start of the rifling. Guns in otherwise good condition could be relined by replacing the inner A tube.
- The USA firm of Crucible Steel supplied some APC and HE projectiles during World War II. Trials with the APC shells showed that their armor penetration was about equal to the ones manufactured by Hadfield and Firth Brown although inferior to the ones made by Cardonald. During firing missions on 06 June 1944, the monitors HMS Erebus and HMS Roberts each had one gun destroyed by bore prematures which were traced to faulty fuzes in these HE rounds.
- According to Nathan Okun, all of the APC shells in use during World War II had similar armor penetration performance with the exception of the special limited-issue APC Mark XVIIb shells developed by and manufactured by Cardonald of Scotland. These had a markedly superior penetration ability due to their harder nose and more rigid middle body. Confusingly, these shells did not get their own Mark number designation, meaning that there were other shells in service with the Mark XVIIb designation that did not have the better penetration capability.
(see Note 2)
|With 1,920 lbs. (871 kg) 4crh AP Shell
MV of 2,400 fps (732 mps) using MD or SC standard charges
|Striking Velocity||Angle of Fall|
|1.0 degree||1,920 yards (1,756 m)||---||1.0|
|2.6 degrees||5,000 yards (4,570 m)||2,074 fps (632 mps)||3.0|
|5.0 degrees||8,629 yards (7,980 m)||---||6.0|
|5.9 degrees||10,000 yards (9,140 m)||1,776 fps (541 mps)||7.3|
|10.0 degrees||14,853 yards (13,582 m)||---||13.0|
|10.1 degrees||15,000 yards (13,720 m)||1,537 fps (468 mps)||13.6|
|15.0 degrees||19,707 yards (18,020 m)||---||21.0|
|15.6 degrees||20,000 yards (18,290 m)||1,377 fps (420 mps)||22.3|
(see Note 3)
|23,734 yards (21,702 m)||---||29.0|
(see Note 3)
|23,387 yards (21,385 m)||---||---|
|22.5 degrees||25,000 yards (22,860 m)||1,317 fps (401 mps)||32.7|
|30.1 degrees||29,000 yards (26,520 m)||1,326 fps (404 mps)||42.0|
|Elevation||With 1,938 lbs. (879 kg) 6crh AP Shell
MV of 2,400 fps (732 mps) using SC standard charges
|Striking Velocity||Angle of Fall|
|2.6 degrees||5,000 yards (4,570 m)||2,144 fps (653 mps)||2.7|
|5.6 degrees||10,000 yards (9,140 m)||1,909 fps (582 mps)||6.6|
|9.3 degrees||15,000 yards (13,720 m)||1,709 fps (521 mps)||11.7|
|13.8 degrees||20,000 yards (18,290 m)||1,556 fps (474 mps)||18.3|
|19.2 degrees||25,000 yards (22,860 m)||1,461 fps (445 mps)||26.3|
|26.1 degrees||30,000 yards (27,430 m)||1,433 fps (437 mps)||35.6|
|30.5 degrees||32,500 yards (29,720 m)||1,446 fps (441 mps)||40.7|
(See Note 4)
|With 1,938 lbs. (879 kg) 6crh AP Shell
MV of 2,575 fps (785 mps) using SC super charges
|Striking Velocity||Angle of Fall|
|2.2 degrees||5,000 yards (4,570 m)||2,312 fps (705 mps)||2.4|
|4.9 degrees||10,000 yards (9,140 m)||2,063 fps (629 mps)||5.7|
|8.0 degrees||15,000 yards (13,720 m)||1,852 fps (564 mps)||10.0|
|11.7 degrees||20,000 yards (18,290 m)||1,683 fps (513 mps)||15.5|
|16.1 degrees||25,000 yards (22,860 m)||1,560 fps (475 mps)||22.2|
|20.0 degrees||28,732 yards (26,273 m)||---||---|
|21.4 degrees||30,000 yards (27,430 m)||1,497 fps (456 mps)||29.9|
|27.9 degrees||35,000 yards (32,000 m)||1,496 fps (456 mps)||38.3|
|30.3 degrees||36,500 yards (33,380 m)||1,507 fps (459 mps)||40.9|
44,150 yards (40,370 m)
New gun MV of 2,638 fps (804 mps) using SC super charges
- There are disagreements between the sources listed below as to the maximum range of these guns. I have chosen to use those figures given in "The Big Gun" for MD charges and those given in "Naval Weapons of World War Two" for SC standard and SC super charges.
- In the "With 1,920 lbs. (871 kg) 4crh AP Shell" table, elevations above 20 degrees apply only to HMS Hood and to the monitors, as these were the only ships as completed that had gun elevations greater than 20 degrees. Ships given extensive modernizations in the 1930s had their mountings modified to achieve 30 degree elevations, but those ships were then issued 6crh projectiles.
- For reasons that are not made clear in the text of "The Big Gun," two different ranges for 20 degree elevation are given for 1,920 lbs. (871 kg) 4crh shells. The first value shown above is presented as part of a table of figures and appears to be from the range tables for this weapon. There is no indication as to what the second figure represents, but I include it here for reference purposes.
- As noted above, super charges were never issued to ships whose gun mountings could elevate past 20 degrees. For that reason, in the super charge table, elevations above 20 degrees should be used only for weapons employed as Coastal Artillery.
- 8crh projectiles were used only by Monitors and only during World War I. These gave a maximum range of about 32,000 yards (29,260 m) at an elevation of 30 degrees.
- Time of Flight.
World War I and World War II performance for 1,920 lbs. (871 kg) 4crh APC Shell with MV = 2,400 fps (731.5 mps)
10,000 yards (9,140 m): 14.6 seconds
20,000 yards (18,290 m): 35.1 seconds
25,000 yards (22,860 m): 48.7 seconds
29,000 yards (26,520 m): 62.1 seconds
World War II performance using Standard Charges for 1,938 lbs. (879 kg) 6crh APC Shell with MV = 2,400 fps (731.5 mps)
10,000 yards (9,140 m): 14.1 seconds
20,000 yards (18,290 m): 32.5 seconds
30,000 yards (27,430 m): 57.3 seconds
32,500 yards (29,720 m): 65.4 seconds
World War II performance using Super Charges for 1,938 lbs. (879 kg) 6crh APC Shell with MV = 2,575 fps (785 mps)
10,000 yards (9,140 m): 13.1 seconds
20,000 yards (18,290 m): 29.8 seconds
30,000 yards (27,430 m): 51.3 seconds
36,500 yards (33,380 m): 69.2 seconds
|Range||Side Armor||Deck Armor|
|8,629 yards (7,980 m)||16.0" (406 mm)||---|
|14,853 yards (13,582 m)||12.0" (305 mm)||---|
|19,707 yards (18,020 m)||11.0" (279 mm)||---|
|23,734 yards (21,702 m)||9.0" (229 mm)||---|
This data is from "The Big Gun" and refers to World War I-era armor plate and probably refers to APC of the early World War I period, not the later, improved "Greenboy" projectiles. This table assumes 90 degree inclination, i.e., an angle of obliquity of 0 degrees. It should be noted that APC of this time did not reliably penetrate at even modest angles of obliquity and were subject to premature bursting, so these values should be used with caution.
|Range||Side Armor||Striking Velocity||Angle of Obliquity|
|0 yards (0 m)||18.0" (457 mm)||2,450 fps (869 mps)||0|
|10,000 yards (9,144 m)||14.0" (356 mm)||1,850 fps (579 mps)||0|
|10,000 yards (9,144 m)||13.2" (335 mm)||1,850 fps (579 mps)||20|
|10,000 yards (9,144 m)||12.2" (310 mm)||1,850 fps (579 mps)||30|
This data is from "British Battleships of World War Two" for uncapped AP shells against KC Plate armor of World War I and probably refers to armor piercing projectiles of the early World War I period, not the later, improved "Greenboy" projectiles. The first two rows are for a projectile striking a plate at an angle of 0 degrees, i.e., with the axis of the shell perpendicular to the face of the plate. The next two rows are for shells striking at larger angles and show the degradation in penetration performance for the same striking velocity as the angle increases. A capped shell (APC) would show about 10 to 20% improvement at low velocities and about 30 to 50% improvement at high velocities.
|Range||Side Armor||Deck Armor|
|17,200 yards (15,730 m)||14.0" (356 mm)||---|
|18,000 yards (16,460 m)||---||2.0" (51 mm)|
|19,400 yards (17,740 m)||13.0" (330 mm)||---|
|21,700 yards (19,840 m)||12.0" (305 mm)||---|
|24,000 yards (21,950 m)||---||3.0" (76 mm)|
|24,500 yards (22,400 m)||11.0" (279 mm)||---|
|28,000 yards (25,600 m)||10.0" (254 mm)||4.0" (102 mm)|
|29,500 yards (26,970 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." This table assumes 90 degree inclination and is based upon theoretical calculations performed in 1935, not actual firing trials.
- Note that the range necessary to penetrate 6.0" (152 mm) of deck armor is at or beyond the maximum range of guns firing SC standard charges at an elevation of 30 degrees.
|Range||Side Armor||Deck Armor|
|0 yards (0 m)||27.1" (687 mm)||---|
|10,000 yards (9,144 m)||16.5" (422 mm)||1.25" (32 mm)|
|15,000 yards (13,716 m)||13.9" (353 mm)||1.95" (50 mm)|
|20,000 yards (18,288 m)||11.7" (297 mm)||3.10" (72 mm)|
|25,000 yards (22,860 m)||10.2" (259 mm)||4.30" (121 mm)|
|30,000 yards (27,432 m)||9.0" (229 mm)||5.70" (145 mm)|
This data is from "Battleships: Allied Battleships in World War II" for a muzzle velocity of 2,400 fps (732 mps) and is partly based upon the USN Empirical Formula for Armor Penetration and partly based upon official data.
In 1921 the British conducted a series of gunnery trials using the last battleship completed by the Germans during World War I, the surrendered Baden. These trials were conducted as a part of the design process for the next generation of capital ships, which were later cancelled as a result of the Washington Naval Limitation Treaty. During these gunnery trials, the monitors Erebus and Terror fired a total of 31 shells using reduced charges in order to obtain striking velocities equivalent to the expected battle ranges. Two primary striking velocities were used, 1,550 fps (472 mps) simulating a range of 15,500 yards (14,170 m) and 1,380 fps (421 mps) simulating a range of 21,800 yards (19,930 m).
Tests at 1,550 fps (472 mps) with 4crh "Greenboy" APC showed that these projectiles could penetrate turret face armor of 35 cm (13.8 in) when struck at an angle of 18.5 degrees and penetrate barbette armor of 35 cm (13.8 in) when struck at an angle of 11 degrees, but that this same armor thickness on the conning tower successfully defeated an APC striking at an angle of 30 degrees. Another test at this velocity saw an APC striking at an angle of 14.5 degrees penetrating the upper armor belt of 25 cm (10 in) and this shell then traveling some 38 feet (11.6 m) before bursting on the funnel casing and damaging two boilers, having first penetrated a 3 cm (1.2 in) splinter bulkhead and the 1.2 cm (0.5 in) main deck.
Five rounds of APC were fired at 1,550 fps (472 mps) at the 10 cm (3.9 in) turret roof armor, with four of these failing to penetrate.
Tests at 1,380 fps (421 mps) with CPC projectiles showed that armor of 17 cm (6.75 in) could be penetrated, but that these shells could neither penetrate nor significantly damage the 35 cm (13.8 in) barbette armor when striking at a 12 degree angle.
There is a cautionary note in ADM 186/251 that may apply to these trials:
Unsteadiness of shells at plate proof - When firing shells with reduced charges to obtain the required S.V. [striking velocity] for the proof or trial of shells or armour, particularly with the larger natures, there is a tendency for shells to be unsteady in flight, as shown by the shape of the hole made in a jump card erected in front of the armour plate. This unsteadiness tends to vitiate the result of the trial. As each round at thick armour may cost as much as £2,000 or more, it is a serious matter to reject the evidence of a round and to repeat it on the score of unsteadiness, although this has sometimes to be done.The Admiralty's overall conclusion from these trials was that the new "Greenboy" APC projectiles had satisfactory penetration characteristics, although their fuzing was not considered successful. Neither the experimental SAPC nor the older CPC used in these trials was considered to be effective. The penetration of the SAPC was disappointing and showed no advantage over APC. The CPC projectiles had considerable blast effect, but the fragments created by their thin walls were too small to cause significant damage.
Data in this section is primarily from "Washington's Cherrytrees: The Evolution of the British 1921-22 Capital Ships" articles by John Campbell, from excerpts of ADM 186/251 provided to me and from "The Baden Trials" article by William Schleihauf.
(see Notes 1, 2 and 6)
|Capital Ship Two-gun Turrets
Queen Elizabeth (4) and Royal Sovereign [except Resolution] (4): Mark I
Monitor Two-gun Turrets
Marshall Soult (1) and Roberts (1): Modified Mark I
(see Note 4)
|Mark I and Mark I*: 770 tons (782 mt)
Mark II: 880 tons (894 mt)
Mark I/N: 815 tons (828 mt)
Mark I/N RP 12: 855 tons (869 mt)
(see Notes 3 and 6)
|Mark I and Mark I*: -5 / +20 degrees
Modified Mark I and Modified Mark I*: +2 / +30 degrees
Mark II: -5 / +30 degrees
Mark I/N, Mark I*/N and Mark I/N RP 12: -4.5 / +30 degrees
Coastal artillery: -3 / +50 or +55 degrees
|Rate of Elevation||5 degrees per second|
(see Note 9)
|-150 / +150 degrees|
|Rate of Train||2 degrees per second|
(see Note 8)
|46 in (117 cm)|
(see Notes 3 and 5)
|Marks I, I* and II: -5 to +20 degrees
Marks I/N and I*/N: -4.5 to +20 degrees
Monitors except Abercrombie: +5 degrees
- The Mark I* differed from the Mark I in that Kenyon Doors were used in place of the shell bogies, otherwise the basic design was the same. The use of thinner armor in the battlecruiser turrets gave them circular front plates while the battleship turrets had polygon shaped front plates. As built, the battleship turrets had 15 foot (4.57 m) MG8 rangefinders that were contained entirely within the gunhouse. Later, 30 foot (9.17 m) MG14 rangefinders were fitted to the rear of "B" and "X" turrets on the battleships and to "B" turret only on the battlecruisers Renown and Repulse. The twin turret mountings each sat on 48 rollers and were hydraulically powered from a ring main using a water/soluble oil mixture. Elevation was by hydraulic cylinder connected to the slide. Each gun was served by two ammunition cages, one for the projectile and one for the propellant. These were loaded separately but then hoisted together to the gunhouse. Cost of a Mark I mounting was £116,000 for the mounting and an additional £32,000 for the two guns.
- The Mark II mount was used only on HMS Hood and had a polygon shaped front plate similar in shape to the battleship turrets. The Mark II turret itself was considerably taller than the Mark I to allow for the increased gun elevations. Besides the increased elevation, the Mark II turrets differed from the Mark I by having thicker armor and as follows: All four turrets had 30 foot (9.17 m) MG14 rangefinders; improved flash-tightness; sighting hoods on gunhouse roof replaced by sighting ports in the turret face (see Note 9); armored officer's cabinet and; hydraulic run-out for the guns replaced by pneumatic run-out (see Note 6).
- The mountings for the monitors Marshal Soult and Marshal Ney had their slide trunnions raised 25.5 in (64.8 cm) in order to allow +2 / +30 elevation (please note, these guns could not depress to the horizon). Other changes involved more powerful elevation machinery, enlarging the gun ports and covering them with 0.5 in (1.27 cm) thick armored hoods and changing to fixed-angle loading. The monitors Roberts and Terror reused the mountings removed from Marshal Soult and Marshal Ney, respectively. The monitor Erebus used one of the two 15" (38.1 cm) Mark I* turrets originally built for HMS Furious in case the 18"/40 (45.7 cm) Mark I guns were unsuccessful. This was modified in a similar manner as the mountings for the other monitors to allow +2 / +30 elevation. All of these Monitors had a fixed loading angle of +5 degrees. The monitor HMS Abercrombie was given the other HMS Furious Mark I* mounting, but this was more heavily modified to the Mark I*/N standard (see Note 6). In addition, the trunk was shortened by about 7.5 feet (2.3 m), the Kenyon doors were replaced by shell bogies, a shell handling room was built with shells transferred from the shell room via four rammer trays and flashtight scuttles were added to the hoppers on the main trunk in the magazine handling room. The flash doors on the gun loading cage were also redesigned.
- There is disagreement between the sources listed below as to the revolving weight of these mountings. I have chosen to use those figures given in "Naval Weapons of World War Two."
- In the original mounting design, the chain rammer was carried on an extension to the slide which theoretically allowed loading to be performed over a large range of elevation, -5 to +20 degrees. However, it was found during World War I that the hydraulic system lacked enough capacity to both run the guns out at high elevations and handle all of the other hydraulic loads. This situation resulted in the mounts "stalling" during gun run-out, greatly slowing the loading cycle. A further problem was that the driving band on the projectiles would not always "bite" into the rifling during ramming. At the higher elevations this failure allowed the projectiles to slide back out of the breech when the rammer was withdrawn, which must have been a fairly "exciting" occurrence. For these reasons, loading was generally performed at +5 degrees or less. Turrets modernized during the 1930s had the run-out problem fixed (see Note 6), but may still have suffered from the projectiles sliding out of the breech at higher elevations. Cordite was rammed two bags at a time.
- During modernizations carried out during the 1930s, Queen Elizabeth, Valiant, Warspite and Renown had their turrets lifted off the ship and sent to the Vickers-Armstrong ordnance works at Elswick for modifications to increase the maximum elevation from 20 degrees up to 30 degrees. This was accomplished by enlarging the gun ports, raising the slide trunnions 8.75 in (22.2 cm) and moving them back 7.25 in (18.4 cm). The guns and slides were moved forward relative to the trunnions by the same amount. This change gave the necessary clearance in the gun wells but the gunloading cage rails had to be moved forward in order to reach the new breech position. There was a penalty in that a 12 ton (12.2 mt) balance weight had to be fitted to the rear collar of each gun. The elevation cylinders and elevation walking pipes also had to be redesigned to accommodate these positional changes and pneumatic run-out was fitted to eliminate the "stalling" problem at higher elevations. Sighting hoods were removed and sighting ports were added in their place, which increased the practical firing arcs (see Note 9). Modified mountings can be easily identified by the "hooded" armor fittings used to cover the larger gun port openings. These modified Mark I and Mark I* turrets were redesignated as Mark I/N and Mark I*/N, respectively.
- The 15" (38.1 cm) Mark I* mountings used on HMS Vanguard were actually old ones removed from the British Battlecruisers (or "Unorthodox Cruisers") HMS Glorious and HMS Courageous which had been placed into storage when these ships were converted into aircraft carriers. While Vanguard was being constructed, these mountings were greatly modified to bring them up to more modern standards. In general, those modifications listed above in Note 6 including increasing the elevation from 20 degrees up to 30 degrees were performed along with alterations to the cordite hoppers on the trunk to improve flashtightness. A significant new addition was having remote power control (RPC) equipment for training fitted - RPC for elevation was not fitted. HMS Vanguard was the only British battleship to have RPC installed for both main and secondary armaments. The increased elevation for the main armament required cutting larger gun port openings in the turret faceplates. To compensate for these larger openings, armored hoods were fitted over the gun ports and the face armor thickness was increased. In addition, 24.5 foot (7.47 m) FX stabilized rangefinders - not 30 foot (9.17 m) rangefinders as stated in many references - were installed on the rear of "B", "X" and "Y" turrets. The corresponding space in "A" turret was used as a secondary conning position. To increase magazine protection, Vanguard's magazines were relocated below the shell rooms (see Note 17), which was the reverse of the arrangement used for all other British capital ships with 15" (38.1 cm) guns, but was similar to the design used for the 14" (35.6 cm) mountings on the King George V class. To accommodate this change, the turret trunks now ended at the shell handling rooms and the magazine handling rooms were located above them. The magazines were connected to the handling rooms by fixed hoists, three each for turrets X and Y and four each for turrets A and B. Something else to note about these mountings is that all four were from ships that did not have superfiring turrets. So, the two mounts destined for Vanguard's "B" and "X" positions had to be substantially reworked in order for them to be used in those superfiring positions. The support structures for all four mountings were stiffened to take the greater recoil forces involved when using supercharges, but as noted above, supercharges were never issued to this or any other ship with mountings capable of 30 degree elevation. Finally, de-humidifying equipment and lagging was fitted to the gunhouse to improve habitability. Vanguard's mountings were now designated as Mark I/N RP 12 (some sources say Mark I*/N RP 12, as the turrets were originally designated as Mark I*, but I believe this to be incorrect). It should be noted that it was only the mountings themselves that came from the battlecruisers, the guns used to arm HMS Vanguard actually came from the reserve stock of spare units.
- The recoil distance given above is the nominal figure. The absolute, metal-to-metal recoil distance was 47.25 inches (120 cm).
- With the exceptions of HMS Hood and HMS Vanguard, superfiring turrets on these ships as built could not fire within 30 degrees of the axis because the blast effects would have penetrated into the lower turrets through the open sighting hoods. From an examination of photographs taken during World War II, it would appear that this problem was not corrected on the other ships except for the four that had major rebuilds during the 1930s (see Note 6). As an example of this, in 1944 the non-reconstructed HMS Malaya mounted 20 mm Oerlikon AA guns atop "A" turret which were thus located directly below the muzzles of "B" turret, which implies that she could not fire "B" turret on a forward bearing.
- After her conversion to "Royal Yacht" in 1947, HMS Vanguard rarely carried any main gun ammunition at all and little secondary or AA ammunition, as she had become badly overloaded. "X" turret was put into a state of preservation and was never made functional again while "Y" turret was rendered inoperable in order to allow the use of a sunroom on the after deck. In 1951 Vanguard was tasked as the Home Fleet flagship but she had become primarily a peacetime status symbol. In 1952 the Gunnery Division of the Naval Staff estimated that it would take seven months to get her operational as a warship again. Main armament shoots were seldom performed during this time and those that were conducted used just the forward turrets and are said to have been primarily intended as morale boosters rather than for serious gunnery training. "HMS Vanguard was a pleasant and spacious flagship, but a Naval Staff anxious to increase her combat efficiency seemed faced with a choice between filling an overweight ship with ammunition or with fuel should she actually ever be made into a fully combatant unit." - Eric Grove in "Vanguard to Trident." In 1955, Vanguard was decommissioned for a refit and weight reduction program which was intended to make three of her four turrets operational and allow them to carry their full outfit of 15 inch (38.1 cm) shells for the first time since 1946. Half of her secondary and AA armament was also to be made functional during this refit. However, this program was halted in March of 1956 and she was then placed in reserve. She was sent to the scrapyard in 1960.
- With the exception of Vanguard, none of these ships were ever fitted with RPC equipment, they continued to use "follow the pointer" gear throughout their careers. Vanguard was fitted with RPC for training, while elevation remained "follow the pointer."
- As part of the studies for new capital ships following World War I, the monitor HMS Lord Clive was used for experiments with triple mountings to test for shell interference problems. She had her 18"/40 (45.7 cm) Mark I and secondary guns removed in 1920 and was then fitted with three 15"/42 (38.1 cm) guns in a fixed broadside mount, firing to starboard. During firing trials in March 1921, one of these guns suffered a bore premature from a faulty, "old type" APC projectile. This burst the jacket and wrecked the gun, slightly injuring one crewman. Other than that disruption, the trials were successfully conducted and concluded that there were no serious shell interference problems for a triple mount.
- The 250 foot (76 m) Radio Telescope at Jodrell Bank, Chesire, England, used elevation gear salvaged from the Mark I mountings on the battleships HMS Royal Sovereign and HMS Revenge.
- "The Big Gun" states that the gun axes for the Mark I and Mark I* were both 90 in (228.6 cm) apart while "Naval Weapons of World War Two" lists them at 98 in (249 cm) apart. I believe that 98 in (228.6 cm) to be correct based upon measurements made on photographs of Mark I mountings. Both of these references and others state that the gun axes on the Mark II were 98 in (249 cm) apart.
- Typical manning of a 15" (38.1 cm)
mounting was 64 officers and men, broken down as follows:
Gunhouse - 17
Working Chamber - 6
Magazine - 12
Handling Room - 7
Shell Room - 22
- Peter Elvin, who in 1942 was appointed as the first full-time damage control officer aboard HMS Renown, reported that the "15-inch gun training hydraulic engines" did not work at list angles "far less than the designed failure angle." During damage control exercises, he was able to quickly heel Renown to a 10 degree list "in just a few minutes" and lists of 14 degrees could be obtained by bulge flooding and "a bit of cross-pumping of liquids." Although he does not specifically so state, the described main-armament training problems may have occured at these larger list angles. Renown at this time had rebuilt Mark I*/N mountings. Resolution was torpedoed in September 1940 and took up a 12 degree list after which time her turrets could not be trained. Resolution had not been upgraded as was Renown and was still armed with her original Mark I and Mark I* mountings.
- The three follow-on "Admiral" class battlecruisers were to have their magazines located below their shell rooms, the first British dreadnoughts so configured. This change was the result of testing in the Chatham float which had shown that if a mine exploded beneath the magazine then water would flood in quickly enough to give a good chance of preventing the magazine from exploding. This arrangement was used in all subsequent British capital ship designs.
- Armor thickness given in "Naval Weapons
of World War Two" and "British Battleships of World War Two":
Except as denoted below, the Mark I and Mark I* turrets were armored as follows:
Face: 12.74 in (32.4 cm) (520 lbs.)
Sides: 10.78 in (27.4 cm) (440 lbs.)
Rear: 10.78 in (27.4 cm) (440 lbs.)
Roof: 4.9 in (12.4 cm) (200 lbs.)
Face: 8.82 in (22.4 cm) (360 lbs.) - Glorious class, Repulse class
Fore Side: 8.82 in (22.4 cm) (360 lbs.) - Glorious class, Repulse class, Vanguard
Rear Side: 6.86 in (17.4 cm) (280 lbs.) - Glorious class, Repulse class, Vanguard
Roof: 5.88 in (14.9 cm) (240 lbs.) - Vanguard, Abercrombie
Roof: 4.165 in (10.6 cm) (170 lbs.) - Royal Sovereign class, Malaya, Glorious class, Repulse class, Erebus
Mark II turrets were armored as follows:
Face: 14.7 in (37.3 cm) (600 lbs.)
Fore Side: 11.76 in (29.9 cm) (480 lbs.)
Rear Side: 10.78 in (27.4 cm) (440 lbs.)
Rear: 10.78 in (27.4 cm) (440 lbs.)
Roof: 4.9 in (12.4 cm) (200 lbs.)
"Regia Marina: Italian Battleships
of World War Two" by Erminio Bagnasco and Mark Grossman
"The Design and Construction of British Warships 1939-1945: Volume I," "The Grand Fleet: Warship Design and Development 1906-1922" and "Nelson to Vanguard: Warship Design and Development 1923-1945" all by D.K. Brown
"British Battleships: 1919 - 1945" by R.A. Burt
"Big Gun Monitors: The History of the Design, Construction and Operation of the Royal Navy's Monitors" by Ian Buxton
"Warship Special 1: Battle Cruisers," "Naval Weapons of World War Two," "Washington's Cherrytrees: The Evolution of the British 1921-22 Capital Ships" article in "Warship Volume I" and "British Naval Guns 1880-1945 No 1" article in "Warship Volume V" all by John Campbell
"Battleships: Allied Battleships in World War II" by W.H. Garzke, Jr. and R.O. Dulin, Jr.
"Naval Weapons of World War One" by Norman Friedman
"Vanguard to Trident: British Naval Policy since World War Two" by Eric Grove
"The Big Gun: Battleship Main Armament 1860-1945" by Peter Hodges
"The Weird Sisters" article in "Warship 1990" by Keith McBride
"British Battleships of World War Two" by Alan Raven and John Roberts
"Anatomy of the Ship: The Battlecruiser Hood" by John Roberts
"The Baden Trials" article by William Schleihauf in "Warship 2007"
"The Battle-cruiser HMS Renown: 1916 - 1948" by Peter C. Smith
"The Royal Oak Disaster" by Gerald S. Snyder
ADM 186/251 (an on-line copy is at Royal Navy Flag Officers Website)
Jodrell Bank Observatory Radio Telescope
Special help from Nathan Okun, Phil Golin and Neil Stirling
06 August 2008 - Benchmark
07 March 2009 - Added cost of mounting and guns, added turret manning breakdown
01 April 2010 - Added burster information on HE Mark VIIIb
31 December 2011 - Added additional information about ammunition outfits and information about "Admiral" class mountings
11 February 2012 - Updated to latest template
14 February 2012 - Updated to latest template
05 March 2012 - Corrected note about shape of turret fronts, added note about armor thickness, added information on 8crh HE projectile
28 March 2012 - Added note about Renown training problems
02 April 2012 - Changed link to Wayback Archive, added photograph of Queen Elizabeth Turret Model
11 June 2012 - Minor changes to improve descriptions
10 December 2012 - Added notes about cordite ramming and firing cycle. Fixed links to HMS Hood guns and FCS pages
15 December 2013 - Added photograph of gun barrel
10 February 2014 - Added range for 8crh projectile and note about Resolution training problems after being torpedoed
27 February 2014 - Added photograph of HMS Hood
29 June 2014 - Added bow photograph of HMS Vanguard
05 October 2014 - Added information to note regarding HMS Vanguard mountings and armor thickness for Glorious class, added bow photograph of HMS Renown
01 December 2015 - Changed Vickers Photographic Archive links to point at Wayback Archive
05 March 2016 - Redid photograph of shell handling on HMS Royal Oak
23 June 2016 - Changed to HTML 5 format