Unlike Anything Else
The few weeks between the end of April and the middle of May 1915 saw new heights in the speed and purpose of the design department. The DNC and Admiral Fisher had found something to agree on, even if it was driven by circumstance rather than any great meeting of minds.
The design of the third ‘large light cruiser’ was recast again. A ship with three turrets emerged, each of which would mount two guns on a 34' diameter barbette and would be of a boxier appearance than the sloped-top turrets of recent years, due to the need to increase the maximum elevation of the guns to 30 degrees. As the 15" Mk.1 entered service with the Navy aboard HMS Queen Elizabeth, it was clear that the step up from 13.5" was an unqualified success. The risk had paid off, and Fisher took the same risk again, as Armstrong’s Elswick works were ordered to deliver a set of 15” 48-cal Mk.2 guns as soon as possible. As with the 15” Mk.1, the first of these would be hurried through in order to test it and to produce a set of range tables.
In the wider naval community, and even in places at the Admiralty, it would remain unclear for some time as to what this new gun was, and what it was for. However, the 15" 48-cal designation did not fool seasoned observers for long, as most could see that Fisher was taking the next step up in firepower, from 12" a few years ago, to 13.5", then to 15", then to what came next.
The hull form of
Glorious was enlarged, with plating and frames being stiffened (even this early, there were doubts about the strength of the first two ships). To further help accommodate the stresses of such a long ship, the hull was deepened by 3' 6", with positive results for the feel of mess decks and the space available for the engines. Hull frames also extended up to the shelter deck, forming a "spine" in the centre of the ship, extending from ‘B’ barbette to just aft of the break in the hull where the foc'sle deck tapered away from the sides. In service, the centre section of the ship was found to be both strong and reasonably stiff, but stresses tended to concentrate between A and B and just forward of X barbettes, resulting in damage when she was driven fast into heavy weather early in her career. Strengthening beams and additional plating later mitigated the problem, but she was always a highly stressed ship.
In place of three boiler rooms with 6 boilers each on
Glorious, there would be four with a total of 32 boilers. By widening boiler and engine rooms, much more power could be delivered without greatly lengthening the vessel, although at some cost to desired improvements in torpedo protection. Each boiler room was to be 65' wide to allow four boilers to be placed alongside each other, with an extra foot added to the outer double-skin of the internal bulge, resulting in a 98' beam. Fisher's worries over underwater defence had grown more acute in recent months, and the ship would be fitted with a 1.75" torpedo bulkhead, in place of the 1.5" fitted to
Glorious.
Machinery consisted of four sets of ‘C class’ geared turbines, with a unique arrangement of double turbines fitted to four shafts. Each shaft had two independent sets of reduction gears and turbines. The arrangement was fine, if a little cramped, for the outer shafts (the forward engine room), but the inner shafts had to be split between Nos 2 and 3 engine rooms, with a machinery room to port of No.2 and to starboard of No.3.
With new guns and machinery ‘borrowed’ from cruiser construction, much of the ship's armour had to come from leftovers or from plating intended for smaller, lightly armoured ships. Here, Fisher was forced to accept something that he would never have done otherwise. Without new orders, the only face-hardened armour available in sufficient quantity was from the now-cancelled Royal-class battleships. Armour plate takes a long time to produce, and the orders for their belt armour had merely been allocated a lower priority when the ships were put on hold at the start of the war. Most of their 6" upper belts had already been claimed by the ‘Renowns’, so with no other options available, designers used the 12" plates ordered for their main belts. Under the ruse that these immense chunks of armour might be needed to repair battle-damaged ships, the order took on a higher priority.
There were also some genuine innovations and improvements. For the first time on a major RN ship, all electrical power would be provided by turbo-generators rather than a mixture of turbine and reciprocating engines. Hydraulic plant was increased to cope with the heavier guns and to avoid problems with elevation and run-out during action. Although the hull was derived from that of the
Glorious, it was beamier, which allowed a slight increase in the depth of the ‘internal bulge’, a curved section of the double hull that protruded from the side of the ship itself. Additional crushing tubes would also be added to help reduce the force of underwater explosions and to preserve some of the buoyancy in otherwise flooded sections.
The armour belt would cover 515' of the 878’ length of the ship, from near the front of A to the rear of X barbettes. The belt itself would be 12" thick and inclined at 12 degrees with the side of the hull. However, it was only 8' deep, and there was no upper belt above it, only 3" of protective plating on the sides that extended to the upper deck over the machinery spaces. A splinter-proof 3" of plating also extended fore and aft of the belt for a total of 275' at the waterline, to provide some protection near the bow and stern. The main belt would be closed by 12" end bulkheads, again just 8' high. As detailed designs were being prepared, concerns over weight growth led to the entire belt being raised by 15", meaning that it projected slightly above the main deck.
The armament would be well protected. Turrets had 13" faces, 4" roofs, with 10" sides and rears, while the barbettes were 11" thick to where they entered the hull, with 7" extending down to the main (armour) deck. Inkeeping with their cruiser heritage, there was no full-length lower deck, and the main deck was therefore directly above the engines, magazines and boilers. As with the earlier Royals, the belt did not therefore protect the armour deck (the main deck) and consequently this was relatively heavy, with a 2" flat and 3" slopes extending down to project 18” below the bottom of the belt. Slopes over the machinery were 4”. The lower deck aft over the shafts and steering gear was 3", and there was a 1.5" lower deck running 125' forward to match the waterline protective plate. The foc'sle forward carried 1" of HT protective plate (increased to 1.5" within 15' of the sides), and the exposed upper deck aft was 1.5”, all of which also contributed to the strength of the ship.
The design reached 34,690 tons at load displacement, and an estimated 39,190 tons deep, for a draught of 25' 5" at load, or 28' 8" deep. At load draught, most of the belt was above the waterline, but at deep load the top was 3' 3" above the waves, with the rest of the huge exposed side of the ship unarmoured against anything more than 6" fire. Following minor revisions to the height of the bulge and to internal stiffening, the ship was laid down on 22nd May.
Fisher's name for his original gargantuan concept had been ‘HMS Incomparable’, however, as the third ‘large light cruiser’, she already had a name that was accepted by the government and Admiralty, and she would be built as HMS
Furious.
. All will become clear in due course...
