HMS Indomitable as completed for trials, without 4in guns atop ‘A’ and ‘X’ turrets, but with water tanks abaft the break of the forecastle, intended to measure the loss of feed water during the trials.
Inflexible shows the two main pre-1914 modifications to the class: the raised forefunnel and the horizontal cylindrical range indicator on the foretop (the one on the maintop is less visible; initially Invincible had only the forward one). Range indicators were removed from all three ships in 1912–13. The single white band on her forefunnel identified her (Invincible had white bands on each funnel, Inflexible one white band on her third funnel). The objects at the rear of ‘A’ turret appear to be foundations for a glare screen, to be erected as desired. Without the usual canvas ‘dodger’ in place, the compass platform shows its two main fittings, the standard compass and a revolving chart table (so that it could be oriented as desired to match the ship’s heading). The vertical object visible abaft the forefunnel is a mechanical semaphore, a standard Royal Navy signalling device of this era.
Indomitable shows why the forefunnel was raised. The range indicator on her foretop is barely visible with even moderate smoke from that funnel. She had her forefunnel raised in 1910, her sister Inflexible following the next year. (Photograph by Cribb via US Navy)
Working up to full speed, probably at the battle of the Falklands (December 1914), Invincible had had at least the 4in guns on ‘A’ and ‘Y’ turrets remounted in her superstructure (note the higher guns forward); it is not clear from this photograph whether the guns on ‘P’ and ‘Q’ turrets were also removed. The other guns in the forward superstructure had had their embrasures turned into protected casemates. A main-battery director has been mounted on the foremast under the foretop and the foretop extended forward, probably to accommodate a 9ft rangefinder (note that the maintop was unaltered). The roof of ‘A’ turret seems to show the bump of a rangefinder. Note the anti-rangefinding spiral on the foremast. Her forefunnel was raised on the way home from the Falklands (February 1915). The after 4in guns were not given shields until after Jutland.
Design A was given to the Committee on Designs after its first meeting. Like some of the battleship designs, it was described as the embodiment of Admiral Wilson’s tactical ideas. He emphasised the need for end-on fire in a chase, hence the two turrets placed side by side. Six of her eight guns could fire on the broadside, should she lie in the line of battle. By this time the Committee was familiar with the blast issue, which seemed to rule out the superfiring turret aft. It also pointed to the considerable target area presented by the two after turrets and to the insufficient command of the aftermost turret. The naval members of the committee objected to the side-by-side arrangement of the forward turrets due both to blast and to loss of seagoing qualities (due to the weight concentrated forward). They wanted an alternative arrangement which would still meet the requirement of ahead fire.
In the absence of complete data on blast, DNC was asked for two more designs, B and C, which adhered to Admiral Wilson’s ideas but reduced blast by eliminating superfiring aft. Design B (17,200 tons) had the two after turrets side by side rather than superfiring. An alternative Design C (15,600 tons) had only one twin turret aft, displacement being reduced to 15,600 tons. Each version showed 41,000 IHP and four single funnels. The thirteen anti-torpedo guns were all in superstructure embrasures. When the sub-committee of naval officers and Admiralty officials considered blast effects, they rejected the side-by-side turrets of B and C. Neither was therefore offered to the full Committee. No practical design could offer the desired combination of end-on and broadside fire. Given the fineness of a cruiser hull (for speed), it would be impossible to group guns near her ends. It also turned out that every further alternative offering good end-on fire also gave good broadside fire, a quality the Sub-Committee liked because ‘it makes the Armoured Cruiser all the more qualified to lie in the line of battle if required to do so’ (italics in the original).
To avoid blast, turrets had to be as far apart as possible. The Sub-Committee asked that two turrets be placed more or less side-by-side amidships. Designs D and E were presented to the Sub-Committee on 5 January 1905. In D, the midships turrets were side by side, so that the broadside was six guns and end-on fire was four (each waist turret could not fire exactly end-on, as sighting positions would become untenable). This arrangement gave the cruiser the same end-on fire as the new battleship. In Design E, the two waist turrets were splayed out fore and aft. DNC decided to move the amidships guns in E towards the centreline, keeping them as close together as possible fore and aft. Presumably that was to move their magazines as far as possible from the skin of the ship. There would be four shafts and possibly turbines (another sheet also dated 7 January indicated that a reciprocating design would have two shafts, a turbine ship four). According to the Committee report, one very great advantage of the new designs compared to those proposed by Wilson was considerable weight saving – 1000 tons – and corresponding reduction in length.
Indomitable is shown as modified by the end of the war. Her bridge structure is little changed, except for splinter mattresses around the various levels and the openwork between the charthouse and the compass platform has been filled in. Above the bridge is a rangefinder. Another rangefinder, probably with an associated director, has been mounted atop the foretop. The box abaft it is a torpedo lookout position. The most dramatic change since before the war is the movement of all 4in guns into the superstructure, in casemates. Atop ‘A’ turret is an anti-aircraft gun. Also evident are the searchlight towers built (after Jutland) around the third funnel, the aircraft take-off position atop ‘P’ turret and a large Carley float just forward of the second funnel. The deflection markings on ‘A’ turret were intended to show other ships in company where the target was; a range dial is just visible on the fore side of the foretop. A reported attempt by the Admiralty to sell this ship and her sister Inflexible to Chile in 1919 failed. Both ships were placed on the sale list before the Washington Conference opened.
At the end of the war Inflexible could be distinguished from Indomitable by the separate platform built above her bridge, around the legs of her tripod foremast. Above it to the left is a forebridge rangefinder. The bulge visible at the after end of ‘A’ turret was a 9ft rangefinder. The vertical object which seems to protrude from the platform abeam her forefunnel was a semaphore, with a searchlight in front of it. One of two 4in high-angle guns is visible on a platform abaft the second funnel. The range dial on the foretop is visible, but the deflection markings on ‘A’ turret are nearly washed out. The frames of an aircraft take-off platform are visible on the guns of ‘Q’ turret.
Inflexible at sea, 1918. Her foretopmast has been taken down. The 4in high-angle gun is between the two forward funnels, the 3in high-angle gun on the port side of her second funnel. ‘Q’ turret shows a flying-off platform with an aircraft; ‘P’ turret on the opposite side of the ship was similarly equipped. The after funnel shows post-Jutland searchlight towers.
Designs D and E were submitted to the Committee on Designs on 12 January. Watts’ cruiser designer Whiting asked what space would be needed in Design E to allow one turret to train on the opposite broadside. The report of the Committee on Designs claimed that each turret was capable of firing over the other broadside within an arc of about 30°, but that did not take blast interference into account. The winning argument seems to have been