Cambrian Class Cruiser (1915)

The four light cruisers of the Cambrian Class were completed in 1915 and 1916. They were sometimes considered repeats of the earlier two-ship Calliope class.

Overview of 4 vessels
Citations for this data available on individual ship pages
Name	Builder	Laid Down	Launched	Completed	Fate
Cambrian	Pembroke Royal Dockyard	8 Dec, 1914	3 Mar, 1916	May, 1916	Sold Jul, 1934
Canterbury	John Brown & Company	14 Oct, 1914	21 Dec, 1915	May, 1916	Sold Jul, 1934
Castor	Cammell Laird	28 Oct, 1914	28 Jul, 1915	Nov, 1915	Sold Jul, 1936
Constance	Chatham Royal Dockyard	25 Jan, 1915	12 Sep, 1915	Jan, 1916	Sold Jan, 1936

Machinery

Generators

In 1916, it was stated that ""C" and "D" class light cruisers" have three 52.5 kw dynamos at 105 volts. As ever, it is anyone's guess where the "C" class designator begins top apply.

Armament

Guns

The ships of Caroline, Calliope and Cambrian classes had their gun armament increased as the war went on.

Original:

• Two 6-in 45cal B.L. Mark XII guns aft on P VII mountings (one source indicates P. VII*), able to elevate 15 degrees.
• Eight semi-automatic 4-in 45cal Q.F. Mark V guns on P. X mountings, two in tandem forward, three on each beam

This configuration drew criticism and it was proposed in 1915 to place a third gun forward in lieu of the pair of 4-in guns originally situated there as:

• the 6-in guns had superior range and hitting power
• the German 4.1-in gun on the opposing light cruisers was found to outrange the British 4-in Q.F. Mark V guns
• intelligence indicated that the next German light cruisers might move to 5.9-in guns and the older ships may also get larger weapons
• it was desired to augment the firepower in closing actions

This resulted in the configuration, decided upon in June 1916 to effect the alteration (all completed by summer 1917) for 12 ships described as the "Calliope class", but by the number 12 almost certainly indicating Calliope, Cambrian and Caroline classes:

• Two tandem 4-in guns forward replaced by third 6-in gun.
• One 4-in H.A. gun on an ad hoc "HA I" or "HA II" mounting to replace 3-pdr Vickers H.A. gun, with a second to appear when guns and proper H.A. III mountings became available.

The 6-in mountings were modified to a 20 degree elevation limit, increased from the original limit of 15 degrees, as the ships were refitted for director firing in late 1917-1918.

The original director-firing arrangements to permit mixed calibres to be commanded by the same director proved less than desireable, and this prompted a decision in mid-1918 to remove the 4-in guns in favour of an all 6-in scheme. It is not clear when and if this occurred.

In October 1916, Commodore, Harwich Force recommended removing all 4-in guns but the forward-most pair which would be converted to H.A. mountings. By removing five 4-in guns, a fourth 6-in gun could be mounted abaft the funnel. A variation on this was to be applied in 1918, though logistics slowed the work:

• all 4-in guns removed except the single H.A. mounting (presumably, H.A. III. There is no solid evidence that the second one was ever shipped)
• Fourth 6-in gun on elevated CL platform abaft funnels (on P VII* mountings, as the P VII supplies were nil)

A final 1918 rearmament was to provide two 3-in H.A. guns in the positions where 4-in H.A. guns had previously been discussed. This plan was never was put into effect.

By the end of 1918, all the Cambrians but Castor had four 6-in P. VII 20 degree mountings and one 4-in H.A. gun. Castor had merely had her three 6-in mountings modified for 20 degree elevation, but was brought up to spec after the Armistice and prior to 1921.

Torpedoes

• 2 Service Bar 21-in submerged broadside tubes amidships depressed 4 degrees and bearing 90.

In 1917, at least some of these tubes were firing 21-in Mark II**** torpedoes and 21-in Mark II***** torpedoes.

The Annual Report of the Torpedo School for 1918 implies that the ships by this date may have mounted torpedo tubes anove water, as they were 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.

Fire Control

Mechanical Aid-to-Spotter

By 1920, these ships were equipped with two Mechanical Aid-to-Spotter Mark II*s with Evershed 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.

Supplies of these devices began in June 1918.

Range Dials

In 1918, it was ordered that these and ten other classes of light cruisers should receive "range instruments for concentration of fire". Presumably, this meant range dials.

As of 1920, none of the ships seem to have been equipped.

Rangefinders

Sometime during or after 1917, an additional 9-foot rangefinder being handed down from a battleship or battlecruiser (likely an F.T. 24) was to be added specifically to augment torpedo control.

By June 1918, it was determined that the ships would probably eventually carry two 12-foot rangefinders.

A confusing decree from 1918 indicates that a traversing 9-foot R.F. on the manœuvring platform on this and three other classes is to be replaced by a fixed 12-foot R.F., "but no addition to the manœuvring platform can be accepted." Also, the roof of the after control is to be lowered and a 12-foot R.F. mounted on it, "but this alteration is not to be carried out pending the trials which are being carried out in Calliope.

By 1921, the ships were equipped as follows:

• Fore bridge: 12ft F.Q. 2 on M.P. 2 mounting
• After control: 12ft F.Q. 2 on M.Q. 1
• High Angle: 1m F.T. 28 on M.T. 9

Evershed Bearing Indicators

The Centaur class were the first light cruisers fitted with Evershed gear for gun control, but it is not clear whether older light cruisers were ever fitted.

Orders for Evershed installations for searchlight control from February 1917 first applied to the Danae class, but seem unlikely to have applied to earlier ships.

Directors

In 1916, it was approved that the ships of this class should be retrofitted with directors as time, resources and opportunity permitted. This intention was reiterated in 1917.

All four were fitted with their directors in 1917 and 1918.

The director was on a pedestal mounting without a tower. Likely, there was no directing gun.

The elevation limits of their weapons may have increased in late 1917 or early 1918, resulting in orders for adapting their director systems issued 13 November, 1917. It is not clear whether these alterations were for the entire class or just Cambrian herself, or when they were effected.

The 6-in guns had 6-in P. XIII Type Elevation Receivers with electrical tilt correction capable of indicating 15 degrees elevation, Pattern V.E. 3. The 4-in guns had 4-in P. X models with electrical tilt correction and 20 degree elevation, Pattern F. C. 5. Their Small Type Training Receivers were pattern number 22 on the 6-in gun #1, pattern number 23 on 6-in guns #2 and #3, pattern number 20 on the 4-in guns.

Dreyer Table

These ships had no fire control tables.

Fire Control Instruments

In 1916, it was approved that the Cambrian (and conceivably her class), should have range receivers in the fore top to show rangefinder ranges, presumably transmitted from the T.S.

By mid-1918, it had been approved to issue these ships, along with several other classes of light cruisers range repeat receivers for their fore bridge and control positions so that their captains and control officers could know the gun range.

Torpedo Control

Torpedo Control Circuits

Torpedo Control Circuits

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 C.T., and that a flexible voice pipe be fitted between these positions.

Additionally, all light cruisers with submerged tubes were to receive torpedo order and gyro angle instruments between torpedo flats and both control positions. The C class (which may or may not encompass the Cambrian class) was to receive Chadburn's Torpedo Telegraphs to meet this need. Otherwise, Barr and Stroud would be a likely choice.

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

See Also

• Wikipedia

Bibliography

• H.M.S. Vernon. (Jan 1916) Annual Report of the Torpedo School, 1915. C.B. 1166. Copy 1025 at The National Archives. ADM 189/35.
• 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.