Caledon Class Cruiser (1916)

The four light cruisers of the Caledon Class were completed in 1917.

In contemporary documents, often referred to as the Calypso Class.

Overview of 4 vessels
Citations for this data available on individual ship pages
Name	Builder	Laid Down	Launched	Completed	Fate
Caledon	Cammell Laird	17 Mar, 1916	25 Nov, 1916	Mar, 1917	Sold Jan, 1848
Calypso	Hawthorn Leslie	7 Feb, 1916	24 Jan, 1917	Jun, 1917	Torpedoed 12 Jun, 1940
Caradoc	Scott	21 Feb, 1916	23 Dec, 1916	Jun, 1917	Sold Apr, 1946
Cassandra	Vickers	Mar, 1916	25 Nov, 1916	Jun, 1917	Mined 5 Dec, 1918

Machinery

Generators

In 1916, it was stated that ""C" and "D" class light cruisers" have three 52.5 kw dynamos at 105 volts.

Armament

The ships were armed as follows.

Guns

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

Torpedoes

• Eight 21-in A. W. tubes on four double revolving mountings 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.

Fire Control

Arrangements were likened to those in the Centaur class, except that:

• the T.S. had a single master push for firing gongs as opposed to one for each group
• the navyphone exchange in the T.S. is a 20-line board (rather than a 15-line board as in Centaur) with a Pattern 3331 in the C.T. connected to it.
• a C.O.S. in the gun director tower can connect the main or aux firing circuits to the Henderson Firing Gear, in line with general adoption of this equipment in all ships with director firing

Mechanical Aid-to-Spotter

By 1920, the three surviving ships were likely equipped with 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

As of 1920, the three surviving ships had two Range Dial Type Cs with 10 foot dials and a single Range Dial Type L.

Rangefinders

Sometime during or after 1917, an additional 9-foot rangefinder was to be added specifically to augment torpedo control.

Evershed Bearing Indicators

These ships may have had Evershed gear for gun control from delivery, as this feature for light cruisers was inaugurated by the Centaur class. The approval for their outfits was issued in 1916.

Orders for Evershed installations for searchlight control from February 1917 first applied to the Danae class, but may not have applied to Caledon.

Gunnery Control

Control Groups

Guns 1 through 3 were a group and guns 4 and 5 a separate control group.

The T.S. had a 3 position C.O.S. for firing, elevation and training signals:

1. all guns on director tower
2. all guns on #4 directing gun
3. guns #1 - 3 on director tower, guns #4 and 5 on directing gun

Directors

Director Firing Circuits

All ships were completed with gunnery directors in place on the tripod foremast. The director was in a tower on a pedestal mounting and was augmented by use of their "X" (or number 4) gun as a directing gun.

Each gun had a local C.O.S. to switch it between director and local firing. Seemingly, these were 2-position, director or local, and lacking the customary option to cross-over the local main and aux pistols and circuits. The gunnery director tower had 3 firing pistols, main, auxiliary and "local", and a 3-position C.O.S. to govern their behavior. It is not apparent to the editor what the "local" pistol did.

The director was powered by either of a pair of motor alternators, with a C.O.S. available to choose which was to be used.

Transmitting Stations

Other than the control details mentioned above, no information on its equipment is available. Presumably, there was at least a range clock, dumaresq, and range and deflection transmitters, and likely in pairs to match the control grouping provided for director firing.

Dreyer Table

These ships had no fire control tables.

Torpedo Control

Torpedo Control, as proposed in 1916

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 Caledon class) was to receive Chadburn Torpedo Telegraphs to meet this need. Otherwise, Barr and Stroud would be a likely choice.

The C.T. and the after control position were equipped with combined deflection, order and bearing transmitters with telltale and receivers, Graham type, Mark I, which connected through C.O.S.es in the T.S. to the crew's shelter positions near the tubes. The aft T.C.P. had a Barr and Stroud Mark III range transmitter wired to a receiver in the C.T., and both control positions had fire gongs to the tubes. The C.T. had voice pipes to the after T.C.P., and both positions had pipes to the tubes. Both T.C.P.s also had Electro-Pneumatic Firing Gear to the tubes.

By 1917, modifications to the torpedo control voice pipe system were desired. The voice pipes (port and starboard) to the C.T. were ordered to be removed in 1917, and in 1918, stop cocks were to be added just abaft the after torpedo positions to allow the after control position to be chopped out to improve the acoustic efficiency of the networks to remaining the rangefinder platform control position forward.

See Also

• Wikipedia

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.