Minotaur Class Cruiser (1906)

The three armoured cruisers of the Minotaur Class were completed in 1908 and 1909.

Overview of 3 vessels
Citations for this data available on individual ship pages
Name	Builder	Laid Down	Launched	Completed	Fate
Defence	Pembroke Royal Dockyard	22 Feb, 1905	24 Apr, 1907	9 Feb, 1909	Sunk 5 Jul, 1918
Minotaur	Devonport Royal Dockyard	2 Jan, 1905	6 Jun, 1906	1 Apr, 1908	Sold 12 Apr, 1920
Shannon	Chatham Royal Dockyard	2 Jan, 1905	20 Sep, 1906	10 Mar, 1908	Sold 12 Dec, 1922

Design and Construction

A fourth member of the class, Orion, was sacrificed from the 1904-1905 estimates along with a third Lord Nelson battleship after the purchase of the two Triumph class battleships from Chile.

Armament

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.

Main Battery

This section is sourced in The Sight Manual, 1916.

The four 9.2-in guns Mark XI were arranged in two double Mark VII mountings fore and aft, able to elevate 15 degrees and depress 5 degrees.

The sights (also used in Lord Nelson class) were gear-worked with a range gearing constant of 32, graduated to 15 degrees (likely 16,300 yards for 2 CRH projectiles). Range dials were provided for full charge at 2825 fps, reduced charge at 2425 fps, another at 2300 fps (possibly only for Minotaur, but likely for all) and 3-pdr sub-calibre and .303-in aiming rifle. MV was corrected by adjustable pointer to +/- 75 fps. The deflection was on a gearing constant of 82.66, 1 knot being 2.49 arc minutes, calibrated for 2875 fps at 5000 yards.

Drift was corrected by inclining the sight carrier 1.5 degrees. The side sighting position with sight lines 32.65 inches above the bore and 32 inches abreast whereas the central position was 38 inches abreast the bore.

A "C" corrector was fitted, presumably also a temperature corrector.

Secondary Battery

This section is sourced in The Sight Manual, 1916.

The ten 7.5-in B.L. guns Mark II were arranged in five single Mark II mountings on each broadside, able to elevate 15 degrees and depress 5 degrees. They could fire 2 CRH or 4 CRH shells.

The sights (also used in Warrior class) were gear-worked with a range gearing constant of 49.28, graduated to 15 degrees (15,700 yards for 4 CRH, 14,200 for 2 CRH). Range dials were provided for full charge at 2800 fps, reduced charge at 2325 fps and 3-pdr sub-calibre and .303-in aiming rifle. MV was corrected by adjustable pointer to +/- 75 fps.

The deflection was on a gearing constant of 72.65, 1 knot being 2.70 arc minutes, calibrated for 2800 fps at 5000 yards. An arrow at 4.5 knots right deflection on the deflection dial was inscribed "Zero for sight testing".

Drift was corrected by inclining the sight carrier 2 degrees and by applying an additional 4.5 knots permanent left deflection when firing 4 CRH shells. The sighting lines with sight lines 11 inches above the bore and 32 inches abreast whereas the central position was 38 inches abreast the bore.A practice gun could be mounted ont he turret roof 65.12 inches above the gun bore.

A "C" corrector was fitted, presumably also a temperature corrector.

Other Guns

High velocity 12-pdr 18 cwt guns were mounted on P. IV* mountings, similar to those in the Lord Nelson, King Edward VII and Dreadnought classes.

The mounting could elevate to 20 degrees and depress to 10 degrees, but though its sight could match the 20 degree elevation, the range dial was only graduated to 14.5 degrees (7,900 yards). This was fine, as there was limited fire control support provided for them and the weapons proved to have little effectiveness at the ranges where torpedo attack became deeply worrying.

The gear-worked sights were similar to the P IV type, but added a cross-connected trainer's sight. They had a range gearing contant of 54 and range dials for 2550 fps, 1962 fps, and 1-in and .303-in aiming rifles. The first series produced corrected for MV with detachable cams for 2600, 2575, 2550, 2525 and 2500 fps. The second series replaced these with an adjustable pointer for +/- 50 fps.

The deflection gearing constant was 63.38 with 1 knot equal to 2.96 arc minutes, corresponding to 2600 fps at 2000 yards. Drift was corrected by inclining the sight carrier arm 2 degrees.

The layer's and trainer's sight lines were 10 inches above the bore, and 10.25 inches abreast.

The sight lacked a "C" corrector. There do not seem to be temperature correctors or open sights.

Torpedoes

In 1909, as heater torpedo supplies were still growing, these ships were to receive two 18-in Fiume Mark III** H. Torpedoes each.

In 1913, it was approved, as part of a general reallocation of 18-in torpedoes, to replace the torpedoes on Minotaur class (except Shannon, which received 18-in Fiume Mark III** H. Torpedoes), Duke of Edinburgh and Bristol classes with Fiume Mark III** torpedoes.

In early 1914, the ships had four Torpedo Director Pattern 2006s and were to have them exchanged for -A models which supported gyro angling.

Fire Control

Fire Control Circuits

Directors

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

Plans to outfit these ships with directors started in early 1915 but were slow to execute. Defence was lost before receiving hers, and the other Minotaur and Shannon received theirs in August and October 1918, respectively.

The Elevation Receivers for the 9.2-in and the 7.5-in batteries were 4-in Triple Type with mechanical tilt correctors, Pattern H. 13. They could indicate elevations up to 15 degrees.

Transmitting Stations

There were two, as one is called the fore T.S. in a 1915 source and the image above clearly can only pertain to this class.

Dreyer Table

These ships had no Dreyer table.

Fire Control Instruments

The ships in this class primarily used Barr and Stroud Mark II Fire Control Instruments.

The Handbook for Fire Control Instruments, 1909 lists their equipment as:

• Combined Range, Order, Deflection: 8 transmitters, 40 receivers
• Group Switches: 4
• Rate: 4 transmitters, 12 receivers
• Bearing: none
• Range: none

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

• Turret fire gongs: 26 with 8 keys
• Fire Gongs: 8 with 2 keys
• Captain's Cease Fire Bells: 16 with 1 key

By 1915, however, some Barr and Stroud bearing instruments had been installed.

The 9.2-in turrets each had 2 bearing receivers that could be driven by a transmitter in the fore T.S. or by one of two special master transmitters mounted port and starboard in the foretop. A C.O.S. in the fore T.S. selected whether the 9.2-in group was driven by the transmitter in the fore T.S. or by one of the masters in the foretop. The fore T.S. had 3 repeat receivers wired off the 9.2-in and both 7.5-in groups to facilitate in changing over. The 7.5-in guns each had a single receiver, and the "special bearing transmitters" in the foretop also had a repeat receiver for their group. The overall bill of fare ran to:

• 2 special bearing transmitters, Graham's type
• 3 Barr and Stroud bearing transmitters (2 in foretop, 1 in fore T.S.)
• 19 bearing receivers:
  • 4 in the two 9.2-in turrets
  • 10 at the ten 7.5-in guns
  • 3 repeats in the fore T.S.
  • 2 repeats in the foretop
• Three C.O.S. (one in fore T.S., and two in foretop)

It is not clear to me why "special" bearing transmitters were required, and how these were made compatible with the B&S receivers.

None of the ships had Target Visible or Gun Ready signals.

Flash Precautions

In early 1915 ships were called upon to report on what extemporary steps were considered necessary to prevent the ignition of charges in casemates, batteries and ammunition passages. The report from Defence read in part:

In this ship the comparative safety of the passages makes the danger less than in many other cases, and with the number of guns to be supplied it is better to accept some risk rather than reduce the rate of fire supply, which anything of real use in this line must do.

See Also

• Wikipedia

Bibliography

• Friedman, Norman (2012). British Cruisers of the Victorian Era. Annapolis: Naval Institute Press. ISBN 1591140684 (on Amazon.com and Amazon.co.uk).
• 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.
• Gray, Randal (editor) (1985). Conway's All the World's Fighting Ships 1906–1921. London: Conway Maritime Press. (on Amazon.com and Amazon.co.uk).
• 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 (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.
• R A Burt. Minotaur: Before the Battlecruiser in Warship, Volume XI Issue 42.