Formidable Class Battleship (1898)

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Overview of 3 vessels
Citations for this data available on individual ship pages
Name Builder Laid Down Launched Completed Fate
Formidable Portsmouth Royal Dockyard 21 Mar, 1898 17 Nov, 1898 10 Oct, 1901 Torpedoed 1 Jan, 1915
Implacable Devonport Royal Dockyard 13 Jul, 1898 11 Mar, 1899 10 Sep, 1901 Sold 8 Nov, 1921
Irresistible Chatham Royal Dockyard 11 Apr, 1898 15 Dec, 1898 4 Feb, 1902 Mined 18 Mar, 1915

Two of the three Formidable class battleships would be lost in the first year of war.


In September 1914, the ships were allowed four additional pairs of Pattern 343 Service Binoculars.[1]


In early 1913, new pattern G. 329 trainer's telescopes of 2.5 power and 20 degree field were issued to these and many other capital ships, to replace the 5/12, 5/15 and 5/21 variable power G.S. telescopes that had previously been in use.[2]

During the war, along with those of other older ships, the eight 6-inch guns casemated on the first deck proved of little use in practical sea states. It was decided to remove the eight casemate guns, plate their ports over and move 4 of them to the upper deck. Four of the twelve 12-pdr guns were also surrendered due to this alteration.[3][Fact Check]

12-in Guns

The 12-in guns were Mark IX, mounted in B. VI twin turrets designated "Fore" and "Aft".[4] These guns fired the same projectiles as, but used a heavier cordite charge than the Mark VIII guns in the preceding Canopus class. The guns' recoil distance was 33-in, and they used a loading angle of 4.5 degrees rather than the previously customary 13.5 degrees. This lower angle was selected as being a better choice for the shorter ranges at which rapid fire would be most suitable (about 4,000 yards here), and it sped the firing cycle, as a return to firing elevation usually happened more quickly than the breech could be closed.[5]

The guns had 6-pdr sub-calibre guns. In late 1913, .303-in aiming rifles for use inside the sub-calibre guns were to be ordered, replacing the use of .303-in barrels that had previously been attached to the chase of the guns. Two were to be supplied by January 1914, and a further two by April.[6]

Implacable's (as in Cornwallis, Duncan, Queen, London, and probably Bulwark) sights and mountings are documented in The Sight Manual, 1916 as follows.[7] It is likely but not certain that the other two vessels were the same.

The mountings could be elevated 13.5 degrees and depressed 5 degrees.

In 1906, the ships were updated to have Africa type semi-direct sights in the centre position and vertical column sights in the side positions.

The centre sights could match the mountings' 13.5 degree elevation, which was 15,800 yards for full charge.[8] They had a range gearing constant of 43.33 and range drums provided for full charge at 2475 fps, reduced charge at 2075 fps, as well as for 6-pdr sub-calibre guns and .303-in aiming rifles. Muzzle velocity was corrected by adjustable pointer between +/- 75 fps.

The deflection gearing constant for the sights was 72.3, with 1 knot equalling 2.7 arc minutes, calculated as 2475 fps at 5000 yards. Drift was corrected by inclining the pivot 1 degree. The sighting lines were 44.03 inches above and 39 inches abreast the bore. No explicit mention is made of a temperature corrector, but there was a "C" corrector able to at least modify the ballistic coefficient by +/- 8%.

The side sighting positions had vertical column sights in which 1 degree of elevation corresponded to 1.05 inches on the strip. Strips were provided for full charge at 2525, 2500, 2475 and 2450 fps, and for reduced charge at 2150, 2125, 2100 and 2050 fps, as well as for 6-pdr sub-calibre and 1-in aiming rifles. M.V. was corrected by strip selection. A deflection gearing constant of 146.7 gave 1 knot equal to 1.4 arc minutes, or 2433 fps at 5000 yards. Drift was allowed for by inclining the sight column 1.833 degrees. The sight line was 42 inches above the bore; its lateral position is not documented. There was no temperature corrector or a "C" corrector.

In 1902, it was determined that an acceptable time for flooding the 12-in magazines was 13 to 12 hour. In April 1904, the longer duration was chosen as a standard for future construction.[9]

6-in Guns

  • twelve 6-in B.L. Mark VII guns

In early 1905, it was approved that the B.L. 6-in guns in Majestics and later battleships should have "A" class cross connected sights, with one V.P. 7 to 21 scope and one V.P.D.N. 5 to 12 scope.[10]

In February, 1913, the 6-in mountings, along with many other 4-in and 6-in mountings in various capital ships and cruisers were to have illumination added for their training index racers.[11]

Other Guns

Twelve 12-pdr guns, later reduced to eight when the 6-in casemate guns were relocated.[12][Fact Check]


The ships carried four 18-in submerged tubes:[13]

  • two forward, depressed 1 degree and angled directly abeam, axis of tube 10 foot 8 inches below load water line and 2 foot 5 inches above the deck.
  • two aft, depressed 1 degree and angled at 20 degrees abaft the beam (an earlier source says 25[14]); axis of tube 10 foot 8 inches below load water line and 2 foot 5 inches above the deck.

Fire Control

Though it may have little relevance given the age difference, the general system of wiring between the in ships prior to Lord Nelson class is illustrated in Handbook for Fire Control Instruments, 1914.[15]


Evershed Bearing Indicators

It is unlikely that this equipment was ever provided.[Inference]


These ships never received directors for main or secondary batteries.[16]

Gunnery Control

The ship's guns were organized in 3 groups:[17]

  1. Two 12-in turrets
  2. Starboard 6-in guns ("A" & "X')
  3. Port 6-in guns ("B" & "Y")

Local Control in Turrets

There was no provision in these ships for local turret control wherein the receivers in the turret could be driven by transmitters in the officer's position at the back of the turret.[18]

Transmitting Stations

In February, 1910, Implacable, the London class battleships and the armoured cruisers still had their transmitting stations aloft. It was decided that ships were to be altered to provide a plotting area with tables and stools near the T.S., equipped with tables, stools and canvas and fearnought screens. A 3-in voicepipe and a navyphone would run between the plotting position and the primary control position, and a navyphone with a telaupad headset would permit communication to the secondary control position. "Spare rate instruments" were to be converted to range instruments to run between the plotting area and the primary control position. Lastly, the primary control position would be able to buzz the plotting station by a buzzer circuit.[19]

The other ships (and perhaps, eventually, Implacable) likely had fore and aft in the pattern typical of similar ships from their period.[20][Inference]

A C.O.S. allowed[Inference] control options of

  1. Fore
  2. After
  3. Separate

Each control group had transmitters with a pair of receivers, one wired directly to the transmitter as a tell-tale, and the other fed off the wires going to the distant guns (i.e., the aft guns for the fore T.S. and vice-versa) as a repeat. "These repeat receivers are necessary to keep the idle transmitters in step; when changing back from separate control they are required to enable both halves of the group to be set alike before being paralleled on to one transmitter."[21]

Dreyer Table

These ships never received Dreyer tables.[22]

Fire Control Instruments

The three ships in this class were equipped in two separate styles.

By 1909, Formidable and Implacable were equipped with:[23]

  • Range (B. & S. Mark II): 6 transmitters, 30 receivers
  • Orders (B & S Mark I): 6 transmitters, 20 receivers
  • Rate (B. & S. Mark II): 4 transmitters, 8 receivers
  • Deflection (Vickers): 6 transmitters, 26 receivers

Additionally, this class had the following Siemens fire control equipment:[24]

  • Group Switches: 3 (converted by Chatham)
  • Turret fire gongs: 8 with 2 keys
  • Fire Gongs: 12 with 4 keys
  • Captain's Cease Fire Bells: 18 with 1 key

Irresistible was equipped with Vickers, Son and Maxim instruments for range, deflection and orders and with Barr and Stroud rate instruments[25] Detailed information is lacking, but might be similar to London class or another such.[Inference]

These ships lacked Target Visible and Gun Ready signals.[26]

In mid-1913 it was approved that these ships receive a Mark III Dumaresq, Pattern 760. Having been supplied with the Mark III variant, each was to surrender a Mark I instrument previously allotted.[27]

Torpedo Control

See Also


  1. Admiralty Weekly Order No. 331 of 8 Sep, 1914.
  2. Admiralty Weekly Orders. 28 Feb, 1913. The National Archives. ADM 182/4.
  3. The Technical History and Index, Vol. 4, Part 36. p. 9. I am inferring here that this class was treated as part of London, Duncan or Canopus classes which are unmentioned in the source, but which straddle this in time.
  4. Manual of Gunnery in H.M. Fleet (Volume I), 1907, pp. 1, 2.
  5. "The Gun Trials of the Formidable." The Times (London, England), Thursday, Jun 13, 1901; pg. 10; Issue 36480.
  6. Admiralty Weekly Order No. 683 of 28 Nov, 1913.
  7. The Sight Manual, 1916. pp. 47, 51, 108-9. Plates 17 and 20.
  8. Range Tables for His Majesty's Fleet. Volume I. 1918. p. 248.
  9. Principal Questions Dealt with by the Director of Naval Ordnance, 1904. (See G. 2520/02) p. 321.
  10. Principal Questions Dealt with by the Director of Naval Ordnance, 1905. pp. 489-91.
  11. Admiralty Weekly Orders. The National Archives. ADM 182/4. 21 Feb, 1913 entries. pp. 3-4.
  12. ditto the inference under "Armament"
  13. Torpedo Manual, Vol. III, 1909. p. 265.
  14. Annual Report of the Torpedo School, 1898. p. 598.
  15. Handbook for Fire Control Instruments, 1914. p. 50 & Plates 50 and 54(I).
  16. The Director Firing Handbook. pp. 142-3.
  17. Handbook for Fire Control Instruments, 1914. p. 8.
  18. Handbook for Fire Control Instruments, 1914. p. 50.
  19. Letter to Fleets and Dockyards G. 196/3429-59, dated 11 February, 1910. The National Archives. ADM 256/44. p. 228.
  20. Handbook for Fire Control Instruments, 1914. p. 50 & Plates 50 and 54(I).
  21. Handbook for Fire Control Instruments, 1914. pp. 50-1.
  22. Handbook of Captain F. C. Dreyer's Fire Control Tables, 1918. p. 3.
  23. Handbook for Fire Control Instruments, 1909. pp. 58-9.
  24. Handbook for Fire Control Instruments, 1909. p. 59.
  25. Handbook for Fire Control Instruments, 1909. p. 56.
  26. Handbook for Fire Control Instruments, 1914. p. 11.
  27. Admiralty Weekly Order No. 283 of 6 June, 1913.


  • Admiralty, Gunnery Branch (1910). Handbook for Fire Control Instruments, 1909. Copy No. 173 is Ja 345a at Admiralty Library, Portsmouth, United Kingdom.
  • Admiralty, Gunnery Branch (1914). Handbook for Fire Control Instruments, 1914. G. 01627/14. C.B. 1030. Copy 1235 at The National Archives. ADM 186/191.
  • Admiralty, Gunnery Branch (1917). The Director Firing Handbook. O.U. 6125 (late C.B. 1259). Copy No. 322 at The National Archives. ADM 186/227.
  • Admiralty, Gunnery Branch (1918). Handbook of Captain F. C. Dreyer's Fire Control Tables, 1918. C.B. 1456. Copy No. 10 at Admiralty Library, Portsmouth, United Kingdom.
  • Parkes, O.B.E., Ass.I.N.A., Dr. Oscar (1990). British Battleships 1860–1950. London: Pen & Sword Ltd. ISBN 0850526043. (on

Formidable Class Pre-dreadnought
  Formidable Implacable Irresistible  
<– Canopus Class Battleships (UK) London Class –>