Armour
Admiralty instructions to the Committee called for ‘adequate protection’ which had to be interpreted in terms of what was possible on an acceptable displacement and cost after priority requirements for armament and speed had been satisfied. The final armour protection of Dreadnought showed no advance over the immediately preceding Lord Nelson class, although the percentage of displacement vis-à-vis protection had increased. Dreadnought’s vertical hull armour was actually inferior, though maximum thickness of deck and internal protection was much stronger. The principal modifications over Lord Nelson were:
1. Maximum thickness of main belt was reduced by 1in, the upper level of 8in being omitted.
2. Lower side armour from fore barbettes to stem was 6in uniform against the 6in and 4in of Lord Nelson.
3. The ¾in upper deck armour amidships was omitted.
4. Middle deck armour between end barbettes increased by ¾in on slope and flat.
5. Lower deck armour forward increased by ¾in.
6. Maximum thickness of turrets reduced by 1in at rears.
7. Conning tower thickness reduced by 1in.
8. 4in and 2in magazine screens added longitudinally.
The reduced thickness of the belt, barbettes, turrets and conning tower was accepted to allow for the addition of the magazine screens which were considered essential protection against torpedo attack or mines, especially the wing magazines which could only be placed approximately fifteen feet inboard of the hull. The actions fought during the Russo-Japanese War indicated that most battleships stood a good chance of survival after being hit by a torpedo provided that an internal explosion did not occur; the screens were fitted in Dreadnought specifically for this reason. Upper side armour above the main deck was abandoned mainly because there was no secondary battery in this location. Another factor that influenced the reduction in thickness of the main belt, from 12in to 11in, was that Dreadnought required a longer strake for her hull, and a 12in belt’s tonnage (which would have added 850 tons to that in Lord Nelson) was not acceptable for the design.
Dreadnought in October 1905, just one week after being laid down.
The completed hull 3 February 1906, seven days before launch (the armour plates are not yet in place).
7 April 1906; the armour plates have just been positioned.
At the fitting-out stage, 11 August 1906.
DREADNOUGHT: FINAL LEGEND
Displacement (tons)
17,850.
Dimensions
Length: 490ft pp
Beam: 83ft
Draught: 26ft 6in
Freeboard: 28ft forward, 16ft 6in amidships, 18ft aft
Gun heights: 30ft forward, 22ft amidships, 22ft aft.
Armament
Ten 12in
Eighteen 12pdr
Five 18in torpedo tubes.
Armour
Main belt: 11in tapering to 4in
Bulkheads: 11in–3in
Turrets: 11in–3in
Barbettes: 11in–3in
Conning tower: 11in
Signal tower: 8in
Communications tube: 5in–4in
Magazines: 2½in–2in
Decks: main ¾in, middle ¾in–1¾in, inclines 4in, lower 2½in–1½in.
| Weight breakdown (tons) | |
| Hull: | 6,100 |
| Armour and backing: | 5,000 |
| Armament: | 3,100 |
| Machinery: | 2,000 |
| General equipment: | 650 |
Fuel
900 tons coal minimum; 2,400 tons maximum plus 900 tons oil.
SHP
23,000.
Complement
700.
It was anticipated that the upper shell plating would act as a ‘burster’ for striking shells, with the armoured inclines on the deck providing the principal protection for the vital parts of the ship below. The Assistant DNC, J. H. Narbeth, recorded that Philip Watts would probably have preferred to have maintained, or even increased, the Lord Nelson standard of protection for Dreadnought, but as the considerably increased displacement involved would have mitigated against the Dreadnought design’s acceptance as a relatively economical type, a lower but admittedly weaker standard was accepted at the time.
Watts had paid particular attention to the underwater protection and subdivision and stated that Dreadnought should be able to sustain hits from one or two 18in torpedoes yet remain afloat. In addition to the six main transverse bulkheads which were unpierced below the main deck level, sufficient stability had been provided to ensure against possible capsizing if some of the compartments became flooded below the middle deck level. Independent pumping, draining and ventilating systems were provided for each compartment; the usual drainage, running the full length of the ship, of previous designs being finally abolished.
Dreadnought’s main armoured belt consisted of an 11in strake which ran from the outer face of the forward barbette to abeam the after barbette. The upper edge was at middle deck level while reaching approximately five feet below the water-line at normal displacement. The 11in thickness tapered at the lower edge of the complete run to 7in.
DREADNOUGHT: LAUNCH FIGURES, 10 FEBRUARY 1906
Displacement: 6,088 tons
Length: 490ft pp
Beam: 82ft 1in
Beam as moulded: 81ft 11¼in
Depth of keel from upper deck: 43ft 2¼in
Length of boiler rooms: 132ft 0½in (144ft 0⅜in incl. cross bunkers)
Length of engine rooms: 68ft 0¼in
Weight of hull: 5,446.6 tons
Breakage at launch:
longitudinal in a distance of 407ft = 1¼in hog
transverse in a distance of 77ft 3in = nil.