Difference between revisions of "Capetown Class Cruiser (1918)"

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===Torpedoes===
 
===Torpedoes===
* Eight 21-in above water tubes on four twin mountings disposed in pairs abreast, bearing 60-120 degrees.
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* four [[21-in D.R. Torpedo Tube (UK)|21-in D.R. Mark II* (?)]] above water tubes (4x2) disposed in pairs abreast, bearing 60-120 degrees.
  
As the 6-in guns fired over these, they proved untenable for manned firing as the 6-in guns would have necessitated a blast shield projecting fully 18 feet from the muzzle.  The ugly expedient taken was to train the tubes to a pre-arranged bearing on coming to action stations and to use remote firing from the primary and secondary control positions.<ref> ''Annual Report of the Torpedo School, 1916'', p. 35.  I am inferring that the faults in ''Caledon'' carried through to this class.</ref>
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As the 6-in guns fired over these, they proved untenable for manned firing as the 6-in guns would have necessitated a blast shield projecting fully 18 feet from the muzzle.  The ugly expedient taken was to train the tubes to a pre-arranged bearing on coming to action stations and to use remote firing from the primary and secondary control positions.{{ARTS1916|p. 35.  I am inferring that the faults in ''Caledon'' carried through to this class}}
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In 1918, the ''Capetown'' class was one of several light cruiser classes ordered to receive refits so that their A.W. torpedo tubes would use two impulse charges firing in a cascade to increase the torpedo discharge velocity and thus reduce the angle at which the torpedoes entered the water.{{ARTS1918|p. 81}}
  
 
==Fire Control==
 
==Fire Control==

Revision as of 08:49, 13 July 2019

The five light cruisers of the Capetown Class (or, sometimes, Cairo Class) were completed between 1919 and 1922. They were follow-on units of the Ceres class, and generally completed after their design successors, the Danae class.

Overview of 5 vessels
Citations for this data available on individual ship pages
Name Builder Laid Down Launched Completed Fate
Capetown Cammell Laird 23 Feb, 1918 18 Jun, 1919 Sold Apr, 1948
Cairo Cammell Laird 28 Nov, 1917 19 Nov, 1918 10 Oct, 1919 Sunk
Calcutta Vickers 18 Oct, 1917 9 Jul, 1918 Sunk
Carlisle Fairfield Shipbuilding and Engineering Company 2 Oct, 1917 9 Jul, 1918 Sold 1948
Colombo Fairfield Shipbuilding and Engineering Company 8 Dec, 1917 18 Dec, 1918 18 Jun, 1919 Sold 22 Jan, 1948

Machinery

Generators

In 1916, it was stated that ""C" and "D" class light cruisers" have three 52.5 kw dynamos at 105 volts.[1] It is unclear whether this outfit was still deemed sufficient for this later class.

Armament

The ships were armed as follows.[2]

Guns

  • Five 6-in 45cal B.L. Mark XII guns on the centre-line with a maximum elevation of 30 degrees.[3] The guns had armoured shields of 1/4 inch on the face, 3/16 inch on sides and top, weighing 1.25 tons.[4]
  • Two 3-in 20cwt Q.F. on H.A. mountings
  • Four 3-pdr
  • Two 2-pdr pom-poms

Torpedoes

As the 6-in guns fired over these, they proved untenable for manned firing as the 6-in guns would have necessitated a blast shield projecting fully 18 feet from the muzzle. The ugly expedient taken was to train the tubes to a pre-arranged bearing on coming to action stations and to use remote firing from the primary and secondary control positions.[5]

In 1918, the Capetown class was one of several light cruiser classes ordered to receive refits so that their A.W. torpedo tubes would use two impulse charges firing in a cascade to increase the torpedo discharge velocity and thus reduce the angle at which the torpedoes entered the water.[6]

Fire Control

Mechanical Aid-to-Spotter

By 1919, all the ships were likely equipped with four Mechanical Aid-to-Spotter Mark II*s with Elliott's Bearing Transmitters. The installations generally consisted of placing one on each side of the foretop, driven by flexible shafting from a gearbox on the director tower.[7]

Supplies of these devices begane in June 1918.[8]

Range Dials

As of 1920, all five ships had two Range Dial Type Cs with 10 foot dials and a Range Dial Type L.[9]

Rangefinders

They were to be supplied an additional 9-foot rangefinder aft, specifically to augment torpedo control.[10]

Evershed Bearing Indicators

These ships almost certainly had Evershed gear for gun control from delivery, and would also feature Evershed installations for searchlight control after orders for such installations from February 1917.[11]

Gunnery Control

Control Positions

Control Groups

Directors

All ships were completed with gunnery directors in place.[12]

The director was in a tower on a pedestal mounting and was probably augmented by use of their 'X' gun as a directing gun. [13][Inference]

Transmitting Stations

Dreyer Table

All five ships are listed in the Dreyer Handbook of 1918 as having a Dreyer Table Mark III*. As of 1930's pamphlet on this table, they are all still so equipped.[14][15]

Fire Control Instruments

Torpedo Control

In 1916, it was decided that all light cruisers of Bristol class and later should have torpedo firing keys (Pattern 2333) fitted on the fore bridge, in parallel with those in the CT, and that a flexible voice pipe be fitted between these positions.[16]

By 1917, modifications to the torpedo control voice pipe system were desired. The voice pipes (port and starboard) to the CT were ordered to be removed in 1917, and in 1918, stop cocks were to be added to permit the after control position to be chopped out to improve the acoustic efficiency of the networks to the remaining rangefinder platform control position forward. [17]

In mid-1920, it was decided that the ships in this class should each receive a Renouf Torpedo Tactical Instrument Type A.[18]

See Also

Footnotes

  1. Annual Report of the Torpedo School', 1916', p. 120.
  2. Conway's All the World's Fighting Ships 1906–1921. pp. 60-61.
  3. Progress in Naval Gunnery, 1914-1918", p. 10.
  4. The Technical History and Index, Vol. 4, Part 34. p. 18. I presume this is what is referred to as "C" class.
  5. Annual Report of the Torpedo School, 1916. p. 35. I am inferring that the faults in Caledon carried through to this class.
  6. Annual Report of the Torpedo School, 1918. p. 81.
  7. Manual of Gunnery (Volume III) for His Majesty's Fleet, 1920. p. 35, 37.
  8. The Technical History and Index, Vol. 3, Part 23. pp. 25-6.
  9. Manual of Gunnery (Volume III) for His Majesty's Fleet, 1920. p. 45.
  10. Annual Report of the Torpedo School, 1917. p. 199. (possibly pertinent: C.I.O. 481/17) I am presuming this is the "repeat C" class.
  11. The Technical History and Index, Vol. 3, Part 23. p. 29.
  12. The Technical History and Index, Vol. 3, Part 23. p. 11.
  13. Handbook of Captain F.C. Dreyer's Fire Control Tables, 1918., p. 142 and plate opposite.
    It is most likely that the details were similar to those of the most recent light cruisers.
  14. Handbook of Captain F.C. Dreyer's Fire Control Tables, 1918. p. 3.
  15. Admiraly. Pamphlet on Mark III* Dreyer Table, 1930, p. 1.
  16. Annual Report of the Torpedo School, 1916. p. 146.
  17. Annual Report of the Torpedo School, 1918. p. 214. CT VP removal per C.I.O. 4037/17.
  18. Annual Report of the Torpedo School, 1919. p. 119.

Bibliography

  • 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 (1910). Handbook for Fire Control Instruments, 1909. Copy No. 173 is Ja 345a at Admiralty Library, Portsmouth, United Kingdom.
  • 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.
  • Admiralty, Technical History Section (1919). The Technical History and Index: Fire Control in H.M. Ships. Vol. 3, Part 23. C.B. 1515 (23) now O.U. 6171/14. At The National Archives. ADM 275/19.
  • Admiralty, Gunnery and Torpedo Division (July, 1919). Progress in Naval Gunnery, 1914-1918. C.B. 902. The National Archives. ADM 186/238.


Capetown Class Light Cruiser
Capetown Cairo Calcutta Carlisle Colombo
<– Danae Class Minor Cruisers (UK) Emerald Class –>