1000 Days-Protection

PROTECTION

Governing the final allocation and weight of armour to be worked into this design was the typical battle-cruiser criterion. That there was to be an overall concentration on offensive power, where armour protection was to be ‘adequate’, after the principal claims of gun-power and high speed had been satisfied.

Since Lion and Princess Royal along with Queen Mary, all shared a common basic design, it is obvious that their system of armour protection should be readily seen to be very similar, and indeed identical in a number of important respects. But differences there were, and the specific details of Queen Mary’s design will now be dealt with through the following sections, dealing with her vertical, horizontal, ordnance, and control positions scale of protective armour. As will eventually be appreciated from the details below, and illustrated in my supporting artwork, the final arrangement and intended weight of armour was a complex and involved facet of this design.

As for its properties, well armour plate had to have two principal features, a firm face combined with a tough elastic back. This was to produce a barrier with a hard impregnable exterior, complemented by a yielding support structure behind: A composite both resistant to penetration, yet capable of withstanding the tremendous impact of a hit without being defeated by the terrible jolt imparted. To achieve this desired dual effect involved a long and complex treatment extending over several months, to improve the carbon content of the surface inch or so of a plate, in what was generally known as the Krupp process. The composition of such a plate comprised of the addition of balanced proportions of chromium and manganese to the basic nickel steel.

Vertical protection

For Queen Mary and her two near sisters, a far greater degree of armour was to be committed towards extending their degree of vertical armour, as compared to the two earlier designs of the lightly protected Invincible and Indefatigable classes. Now no less than 3,878t of armour was to be allocated towards just the hulls vertical protection alone. Along the waterline lay the principal component of her belt, which consisted of a 9 inch thick commitment of armour extending for 324 feet 6 inch, covering a fair proportion of her 698 feet waterline length: This main belt embraced the hull from abreast the conning tower forward, to just inside the trace of ‘Y’ mounting aft. The 11 feet 4 inch total height of this belt had its upper edge at main deck level, approximately 8 feet 5 inch above the legend waterline. This strake was composed of a series of massive sections, mounted and bolted externally onto the thin skin plating of the hull, backed by balks of teak running the full length of this section abreast the vital citadel.

Forward of this main belt there was a 61 feet 7 inch long by 11 feet 9 inch deep, 6 inch thick armoured strake covering the area to ‘B’ barbette. Which was reduced to a 5 inch thick 51 feet 8 inch long by 12 feet, 6 inch deep section just beyond this to ‘A’ mounting. These components primarily covered the ships forward shell rooms and magazines, while located beyond this was a 4 inch thick 61 feet 4 inch by 12 feet 8 inch section of plate. Aft the waterline and ‘Y’ mounting was protected by weights of 5 inch then 4 inch plate, the former adjoining the main belt being a 36 feet 4 inch by 12 feet 4 inch constituent, the latter a 39 feet 8 inch by 12 feet 7 inch one.

In this design one of the principal advances over previous layouts was in the adoption of an upper side belt. This was a significant improvement over the Invincible and Indefatigable designs where there was none above the principal waterline belt. Amidships there was a 6 inch thick upper belt allocation of armour extending over the same 324 feet 6 inch length of the citadel as the main belt, protecting the hull between the main and upper deck levels to a height of 7 feet 10 inch. Forward at this level a 5 inch thick 113 feet 5 inch by 7 feet 8 inch section was present, with a 4 inch thick 61 feet 4 inch by 8 feet portion beyond this. Aft a 5 inch thick 31 feet 5 inch by 7 feet 9 inch, then a 4 inch thick 44 feet 9 inch by 7 feet 10 inch section finished off this area of protection.

This varied and extensive vertical commitment of armour stopped 50 feet before the raked stem, while aft it ceased some 73 feet from the stern, with the upper portion of the latter forming a 10 feet step forward: Completing her principal vertical armour there were internal bulkheads forward and aft, sealing off the ends of the citadel extending between the lower and upper decks. At Frame 18 forward there was a 4 inch thick 20 feet wide by 19 feet 7 inch deep bulkhead, while aft at Frame 287 ran a 41 feet by 19 feet 6 inch bulkhead with a similar allocation of plate.

Brief mention should also be made here of some areas of light vertical protective plating set well in board: Between the upper deck and forecastle amidships there where a series of relatively thin longitudinal bulkheads, helping to protect the vulnerable funnel and vent uptakes. In Queen Mary these screens were of a uniform 0.75 inch plate, as opposed to her near sisters varying distribution of between 0.5 inch to 1.25 inch for these internal barriers to splinters and blast.

Below the waterline abreast the main magazines and shell room compartments there where additional vertical protective screens of between 1.5 inch to 2.5 inch of armour for ‘A’ and ‘B’ mountings. While ‘Q’ mounting amidships had a 1.5 inch screen set well inboard to port and a 2.5 inch screen offset to starboard nearer the shipside. ‘X’ aft had a uniform 2.5 inch set of magazine screens out board of it.

Underwater

For the hands of the submerged portion of her structure, there was no provision for a specific longitudinal torpedo bulkhead set well inboard as a defence against underwater hits, just a reliance upon the hulls extensive cellular double bottom. The principal element in Queen Mary‘s underwater defence rested on her series of lateral vertical internal bulkheads, which where un-pierced by any potentially weak watertight doors up to 9 inch above the legend waterline. These effectively formed a series of watertight compartments running athwartship the length of the ship.

As was to be seen in the war on a number of occasions, the penetration effects of a torpedo, mine, or plunging projectile, as well as hull Fragments from such contacts, could easily pierce such a lightly armoured lower hull arrangement. This is seen in the shell hit received by Lion at the Dogger Bank below the waterline. And the serious mine damage sustained by both the Inflexible off the Dardanelles and the Audacious off Rathin Island, the latter ship being lost. It was envisaged that this scheme could absorb two torpedo hits without any critical degree of flooding, although it has been accepted that this system was basic and could be defeated. However it could also survive underwater damage, as was to be clearly displayed by the Marlborough, which absorbed a torpedo hit quite well at Jutland, and remained in the line.

Horizontal protection

The overall scale and weight of protective plate dedicated towards this battle-cruisers decks was on a relatively lean scale. With the upper deck having a thickness of between 0.75 inch to 1 inch of plate covering the citadel. However this was deemed quite acceptable at this period, with all navies building capital ships, which envisaged short-range gunnery duels, were hits on the horizontal plane were expected to be minimal.

In cross section through the ship the armoured lower deck had its outer extremities sloping down at the edges in a gentle curve, with its crown at the normal waterline, and its lower curved edge joined to the bottom of the armour belt 3 feet below the legend waterline. Extending forward and aft beyond this heavy belt armoured-citadel there where increases to 2.5 inch thick deck sections towards the more exposed stem and stern.

Horizontally there were a number of significant structural openings necessary for the functioning of the ship. These where for her barbettes and those for her series of funnel uptakes and ventilator trunks servicing her numerous boilers and engineering spaces. These vents and uptakes being protected by sections of perforated armour grill designed to be effective in sealing of these openings against the entry of projectiles. But they were obviously susceptible to the entry of blast, flames, and fumes as well as to smaller Fragment and splinter entry through the grill mesh.

Ordnance protection

For the allocation of armour granted to the main 13.5 inch mountings, here there was a fairly respectable provision. For each gun-house 9 inch was provided for its face and sides, with 8 inch for the rear. The crown was provided with 4.25 inch on its forward portion, 3.5 inch across its central strip, and 2.5 inch towards the rear. A 2 inch thick floor was also provided to the after portion of the gun-house overhanging beyond the barbette. The various essential openings in a gun-house, for embrasures, manholes, sighting ports, and periscopes, were themselves all suitably protected by armoured plates, hoods and hatches. But as experience was to show in the first winter of the war, the weatherproofing seals of such features left much to be desired.

The barbettes with their 28 feet internal diameter, upon which these revolving structures rested, where given varying degrees of protection depending upon the coverage of supporting structural armour, and the expected exposure to enemy fire. For example, above the armoured deck the barbettes in ‘A’ and ‘B’ positions where given 9 inch to their most exposed portions, that is abeam and ahead, reducing to 8 inch toward their rears. While amidships ‘Q’ concentrated its armour on the beam and ‘X’ on its beam and aft face. Below this principal level of greatest exposure, the barbette armour for these mountings was thinned considerably behind areas deemed covered by Queen Mary’s vertical armour, to a light 3 inch cover for the forward mountings, and between 3 inch to just 1 inch amidships. The aft barbette was given an overall 4 inch cover for its lower portion.

As for the armour dedicated towards Queen Mary’s 4 inch secondary batteries, deployed in two widely dispersed groups of eight 4 inch pieces separated by her funnels and ‘Q’ mounting. Here only the forward battery was granted protection, which involved 3 inch plate to its sides crowned by a 1 inch roof, and a 3 inch thick partial bulkhead to its rear. This arrangement was quite adequate at defeating splinters or light hits, and was better that the position aft where nothing other than light gun shields was provided for the after 4 inch battery. It should be noted that the two Lion’s had no armour allocated to their 4 inch secondary batteries, and that they had a significantly different two story arrangement for their forward mountings. A good identification point to segregate the two groups.

Control

For the conning tower with its roughly oval shaped trace and maximum 15 feet internal dimension, 10 inch armour graced its 6 feet 8 inch high sides. Topping it a crown of 3 inch armour was present, upon which a 3 inch armoured sighting hood was located, with the position completed by a floor of 4 inch thick plate. A 2 feet 6 inch internal diameter communication tube of between 4 inch to 3 inch of armour descended down from the position to the lower conning tower. With its upper 27 feet 1 inch portion having the heavier armour allocation, while the lower 14 feet 2 inch section was of the lighter weight.

For the spotting platform located atop the foremast, just two layers of 0.75 inch plate were all that was employed, basically to splinter proof this very visible and open position. The director tower fitted during the war only had 1 inch protective plate, again only really proof against splinters. Obviously weight and stability considerations precluded any heavy armour being worked into these high commanding positions. Located to the stern of the after superstructure, the torpedo control tower was a well protected position, judging by its assigned uniform 6 inch armour to its sides along with a 3 inch roof and a 4 inch floor. This was in direct contrast to Lion’s minimal 1 inch armour overall for this position.

German projectiles

In this part of this review, it will be of pertinent interest to look at the principal devices, which this armour scheme was expected to counter, the main guns and Armour Piercing Capped (APC) shells of the German battle-cruisers.

The 11 inch SKL/50 piece carried by the Seydlitz and Moltke weighed 41 tons and had a length of 47.4 calibres. An APC shell from this device weighed 666 pounders, and its 174 pounder main, and 57 pound fore charge propellant, could enable its shell to reach 21,300 yards with 16 degrees of elevation on the piece, and had a muzzle velocity of 2,887 feet per second (fps).

The 12 inch SKL/50 piece carried by the Derfflinger by comparison were of 51 tons and had a length of 47.4 calibres. An 893 pound AP shell from this gun could achieve 22,900 yards with 16 degrees of elevation, and a muzzle velocity of 2,805 fps.

Both of the projectiles mentioned had a small internal cavity sufficient to allow a bursting charge to be inserted, which accounted for approximately just 2% to 2.5% of the shells total weight. Such a device through its streamlined and pre-stressing cap, was intended to defeat armour plate up to a 15 degree angle of contact, and still be in a condition to detonate within an enemy’s structure with a reliable fuse.

The Test

Although the basic facts and figures about the scale and weight of armour allocated to Queen Mary and her kind, has now been documented. Exactly how well did it perform, not in theoretical considerations, nor under artificial tests and shoots, but in the hard proving ground of actual battle. This was after all the telling trial under which its true qualities and deficiencies would have been fully revealed. While theories and hypothesis about this aspect of this ship’s design May be informative, it is in this question of how such an armour scheme truly withstood the rigours and demands of projectile hits and detonations in battle, which will finally produce factual results upon which to base all criticisms.

In this endeavour to discover the true weaknesses, and strengths, possessed by Queen Mary’s armour we must encompass the experiences of all her very similar 13.5 inch gunned sisters. To now draw up as wide a field of data as is possible, with which too finally define any conclusions upon. This investigation will directly involve Lion, Princess Royal, and Tiger. With a commentary on how they performed at the two Major battle-cruiser actions of the First World War, those of the Dogger Bank, and Jutland: Note that here no mention of Queen Mary herself included in this section. Since she missed the first of these actions, and was lost at the second instead this examination into the estimated hits at her end, along with their possible effects and extent, lies within the relevant chapter at the close of this book.

Lion: At the Dogger Bank, she was hit by sixteen 12 inch and 11 inch shells plus one 8.3 inch shell from the Blucher. In this the crown of ‘A’ turret was dished by the 8.3 inch shell, while of the heavier devices which hit, one defeated her 6 inch side armour and the 5 inch portion was defeated twice. Fragments of a hit on the weak junction of her 6 inch and 9 inch belts penetrated inboard: But the main 9 inch belt itself managed to defeat two projectiles and was never breached. However a number of underwater hits occurred below her armour. The principal result of this was that her port engine room became flooded. Later progressive flooding forced the shutdown of the starboard room, resulting in her having to be towed home to Rosyth by the Indomitable. But since only one man was killed from these hits, this is a clear indication of how well protected her personnel and therefore vitals where, despite this potentially serious damage to her machinery. At Jutland she was hit thirteen times by 12 inch shells from the Lutzow and Derfflinger. From this relatively acceptable impact, blast and Fragmental damage to both armour and light structures occurred, only one telling hit was received. This was on the junction of the forward section of roof and faceplate of ‘Q’ turret, which was pierced, killing and wounding all in the gun-house and knocking the turret out of action. But more seriously due to smouldering debris inside the gun-house a cordite fire commenced 28 minutes after the initial hit which completely gutted the mounting, and greatly contributed to her total of 99 men killed in this action.

Princess Royal: Not hit at the Dogger Bank. But at Jutland she received eight 12 inch and one 11 inch hits. In this inventory of blows, her 6 inch belt was penetrated twice, one of the shells expending its force in pulverising the contents of a coal bunker inboard, while the other tore a 17 feet long strip in the 1 inch main deck before being deflected to the upper deck. Another hit on her 6 inch belt broke up on impact, as did another on the junction of the 6 inch and 9 inch belts. A hit on the 9 inch armour of ‘X’ barbette was deflected down through the 1 inch deck and the resulting structural damage jammed the turret. However her ability to manoeuvre was never impaired.

Tiger: Hit by six shells during the Dogger Bank action. The most serious of which jammed ‘Q’ turret after a hit on its crown between two plates enabled Fragments to enter. At Jutland she was struck fifteen times. In this ‘Q’ turret’s roof was again holed which reduced the efficiency of the turret. ‘X’ barbette was holed at the junction of the 9 inch and 3 inch portions with the 1 inch upper deck, which dislodged a section of plate with serious effects upon the working of the turret. As for her side armour, her 5 inch portion was defeated once, while a second hit was deflected off. The 6 inch belt was pieced once, and another hit forced in a section about 3 inch, a blow on her principal 9 inch belt forced in a section about a maximum of 4 inch in the area of impact.

From the above details it is apparent that under actual battle conditions, the degree and amount of armour provided for the Royal Navy’s 13.5 inch gunned battle-cruisers, performed well and satisfactory against their German opponents. There is no instance of the direct penetration of any main plate recorded. The closest this comes was when a hit impacted upon the junction of the 9 inch portion with lighter surrounding sections. Although 5 inch and 6 inch armour could be defeated, in a number of instances it broke up or deflected a projectile. For the gun-houses the face and sides were secure, but here their crowns could be penetrated, again especially where different weights of plate joined together.

But as Lion and Tiger displayed, although penetration of a gun-house might instigate a serious cordite fed fire in that mounting, or disable a turret, it was not the automatic initiation of a subsequent fatal magazine explosion, as some would believe. Finally, horizontally all thickness of armour could be defeated. But the ability of the scheme’s arrangement of armoured levels, to slow, deflect, and minimise the effects of shell penetration is apparent, with none having telling or fatal deep penetration consequences into a ships vital citadel.

Torpedo nets

Although not usually included under a standard description of a ship protection, Include within this section is a mention of what was by then becoming a naval anachronism, anti-torpedo nets. Here Queen Mary’s possessed such a defence throughout her brief existence. This was deployed only when she was at anchor, and as will become quite manifest in the ensuing coverage on her career, the evolution of getting out and in the net defence was a frequent one, and her crew where well versed in it.

For Queen Mary this installation, totalling 68t comprised of a series of seventeen heavy wire net sections on both sides, approximately 25 feet by 28 feet in size, of a close mesh that weighed 5 pound per square foot. These where suspended from mainly 40 feet long steel booms secured to the ships side. In operation to a well-practised crew, bringing the nets inboard took just a few minutes, hoisting them up to their 2 feet wide storage shelves in one continuous roll. While lowering them would take even less.

Verdict

Through the practical experiences of her 13.5 inch gunned sisters, and an appreciation of what might have occurred to Queen Mary herself at Jutland, it is apparent that this basic protection performed well in action. Obviously its lighter weight of plate and points of union could be defeated, but indications present us with a picture of a reasonably secure citadel, and well-protected vital heart to the ship.

In closing this section about the scale of armour, the average reader might have become blind as to the full weight of plate, and amount of material actually worked into such a leviathan as this subject. To put this in very simple terms, one interesting fact puts this all into perspective. And that was just a one foot square section of 1 inch thick armour plate, some of the lightest plate encountered in this design, weighed no less than 40 pound.

This should give one a comprehensible and realistic impression of the imposing scale of the task confronting a naval architect, endeavouring to fully protect such a massive structure as a 700 feet long 89 feet beamed vessel against all eventualities. With this basic appraisal in mind, perhaps the general qualities of Queen Mary and her kind, so long the butt of adverse comments and observations, should now be seen in a more objective and favourable light. As a successful merging of the conflicting requirements which went to make up her structure, and desired performance. Admittedly the penetration effects of an enemy device did contribute to her subsequent loss, but the really fatal flaw in her fabric lay elsewhere, a factor now to be investigated.