Bellerophon shows wartime modifications in this 1918 photograph taken at Scapa Flow. The added searchlight platforms on her foremast remain, but the platforms abreast her forefunnel are gone and ‘coffee box’ searchlight platforms have been built up around the after funnel. Her foretop had been enlarged to house a rangefinder, but a larger-base one was later added atop it. A director (with coaming for splinter protection) has been added on a new platform under her foretop. Her foretopmast was landed and her maintopmast cut down, to make it more difficult for an enemy to estimate her course at long range. Note that all 4in guns are now in the superstructure, in embrasures above the original ones. This work was done in three stages. First the two 4in atop ‘A’ turret were moved to the superstructure when the searchlights were rearranged. Then the guns from the waist turrets were moved and finally the two from ‘Y’ turret. Two 4in anti-aircraft guns are visible aft. The gun right aft was originally atop ‘Y’ turret, then relocated to the quarter deck in 1918. Note the prominent funnel cap (clinker screen) and the empty casemate for 4in guns on the fore end of the after superstructure (this gun was removed in 1914–15).
A Board discussion (12 December 1906) concentrated on J4(F) and J6. Design F offered seven guns firing end-on, ten on the beam and five on the bow and quarter. Of the ten, two had arcs of training probably not exceeding 70°. J6 offered three guns firing end-on but nine on the beam and all nine would have arcs as good as those offered by eight of the ten guns of Design F. DNO stated that recent experiments showed that fire control was more difficult with four than with three turrets. He also suspected that there would be blast interference between the two waist turrets firing broadside. By way of contrast, the turrets in J6 were well separated and would not suffer blast interference. The ship would be smaller and less expensive, with shallower draught. The main objections were weak ahead and astern fire. Also, the ship would lose a greater percentage of her battery if one of her turrets was disabled. Moreover, the triple turret was very much an experimental proposition. If it failed, J6 would be reduced to six guns, but F would still have eight.
Temeraire shows all wartime modifications, at the surrender of the Russian Black Sea Fleet to the Allies, 26 November 1918. The most prominent changes visible here are the redistribution of searchlights ordered after Jutland. The raised foremast searchlight position survived from the 1914 modifications, but her compass platform did not project as far forward as in Bellerophon. (Dr David Stevens, RAN Seapower Centre)
Bellerophon in 1919, with flying-off platforms on ‘A’ and ‘Y’ turrets.
Even though end-on fire was not considered vital, it was considered undesirable to go so far as J6. Apart from increased displacement, there would be no more objection to using only triple turrets in F than to using all triples in J6, but that would give a twelve-gun ship. That might be entirely worthwhile. Watts formally submitted details of the two 1907–8 designs on 5 December 1906 and Controller told him to proceed with drawings. Design F was approved at an 11 December 1906 Board Meeting. DNO (Captain Jellicoe) asked the two gun-mounting builders, Elswick and Vickers, for designs for triple 12in turrets. On 12 December 1906 Jellicoe provided estimates of the difference in weight between twin and triple turrets. Including both fixed and rotating elements, a triple turret would weigh 1033 tons, a twin (as in Lord Nelson), 792 tons.11
The battlecruiser began as an improved Invincible with larger training arcs for the two waist turrets, so that they could fire across deck over wider arcs (60–70°) and with heavier armour.12 The first Legends were dated 21 November 1906. The design was discussed at a 22 November conference and DNC had modified it as desired at the time. The main changes were the 12in/50 and increased power to regain the 25 knots of the Invincibles.
The initial version (A) was simply lengthened (from 530ft to 550ft) to offer the larger arcs (18,100 tons), but an improved version (B) had 9in armour amidships (over a 200ft length). B might be considered an approach to a fusion design, but it (and later versions) retained the thin turret and barbette armour of the original Invincible. A further version (C) added 4in stern armour (Invincible and the others had none). It would have displaced 18,900 tons. Since the new design had the same powerplant as the original, the extra features cost speed: half a knot in A and B, three-quarters in C. At this point Invincible was still credited with 12pdr anti-torpedo guns, but the alternative designs showed sixteen 4in. None of these designs incorporated the new 12in/50 gun. A slightly later Legend added the new gun. The ships were further lengthened to 560ft, the alternatives being 9in, 6in and 4in side armour (A) and 10in, 8in and 4in side armour (B). On this basis A displaced 19,700 tons and B displaced 19,900 tons; each lost a knot compared to Invincible. A further design (C) had 10in and 8in side armour and would have been lengthened (to 565ft) to retain its 24-knot speed without extra power. This ship would have displaced 20,700 tons. A later Legend shows a slightly modified but heavier (20,900 tons) Design D.
The next step (E) was an attempt to gain back speed by increasing power from 41,000 IHP to 48,000 IHP (equivalent) and reducing the side armour to 9in. Compared to Invincible, Design E had more powerful guns (12in/50) and better protection: a 9in belt (with 7in above it to the main deck), the belt tapering forward, with a 4in bulkhead 50ft from the bow; 1½in armour was added aft. Torpedo bulkheads protected machinery and magazines, as in the Bellerophons. The ship was lengthened by 25ft (to 565ft; length overall would not exceed 600ft). She would displace 21,300 tons, 700 tons more than the Design D which had been discussed at a Sea Lords conference. Compared to D, E was faster (25 knots rather than 24 knots) and had an inch less side armour (but a longer belt). Design E was also approved at the 11 December 1906 Board meeting.
The Battleship F design was submitted to the Board in February 1907. At that point the ship would have displaced 19,750 tons and would have required the equivalent of 24,250 IHP, compared to 23,000 in the previous generation of dreadnoughts. There would be twenty 4in anti-torpedo guns. The main belt, 10in thick, extended further fore and aft than in previous ships, so as to completely protect the magazines of the guns of the triple turrets at the ends of the ship. Extending forward to the cable locker was a 7in belt closed by a 5in to 4in armour bulkhead, with 2½in armour forward of that (the cables themselves would add protection in the bow). Abaft the after end of the 10in belt the ship had 2½in armour. The lower protective deck aft was 3in thick from armour bulkhead to stern, compared to 2in flat and 3in slopes in the previous class. The main deck was made 1½in thick from the forward armour bulkhead to the forward barbette, compared to ¾in in the previous class.
On 27 April Controller set out the dates by which the Board had to approve drawings: 16 July 1907 for the contract ship (Battlecruiser E) and 1 July 1907 for the battleship (F), which was to be built by Royal Dockyards. One battleship was to be laid down in November 1907 at Portsmouth, the other at Devonport in December.
As the designs evolved, by June 1907 the estimated displacement of Battlecruiser E was 22,000 tons, about that of the earlier fusion design. Plans changed dramatically after a 12 June 1907 Board meeting intended to discuss the 1908–9 programme. Dreadnought and the three 1906–7 ships formed a homogeneous squadron. The Board decided that it wanted a second homogeneous squadron, which would consist of all three 1907–8 ships and one 1908–9 ship. The projected 1907–8 battlecruiser was therefore dropped in favour of a third battleship.13 That killed Battlecruiser E. Some time late in June DNO became convinced that the triple turret should not be adopted. On 4 July the Board decided to revert to the earlier arrangement of five twins. The improved armour distribution and the 12in/50 gun would be retained. Overtime was approved to get the new drawings out (they were already late, given Controller’s timetable).