Acorn Class Destroyer (1910)

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Twenty destroyers of the Acorn Class were completed between 1910 and 1912.

They were re-designated as "H" class destroyers in October, 1913.[1]

From 1912-1916, they were serving in the Second and Fifth Destroyer Flotillas.[2][3]

They were the last British destroyers to feature a hand steering position.[4]

Fittings

Minstrel and Nereide had experimental water-excluding ventilators, and were asked to report on their effectiveness just as the war was about to start.[5]

In October 1914, as the Acorns were all serving in the Second Destroyer Flotilla, they were ordered to have the (hydraulic?) searchlight control system first used in H.M.S. Badger fitted.[6]

Performance

They burned oil, unlike the Beagles, delivering the same 27 knots on a displacement 200 tons lighter.[7]

While the individual ships certainly varied widely, they were described as having a radius of 2250 NM at 13 knots.[8]

Acorn achieved 4 miles to the ton of coal at 27.5 knots. Redpole topped out at a spry 30.61 knots in rough weather! Comet had the smallest tactical diameter (402 yards starboard, 536 port, advance of 354 yards), and Redpole had the worst diameters at 728 yards to starboard and 608 to port. The ships burned around 7 tons per hour at full speed and 0.75 tons per hour at cruising speed.[9]

In foul weather, the commander of Goldfinch commented, "I cannot say anything bad enough for the chart house, all charts ruined and a foot of water on deck, even battened down with all deadlights screwed down hard the water poured in, even through the keyhole..." but praised the ship as "simply perfect to handle and turns wonderfully considering her length." In especially severe seas, the Beagles came through fine, but the Acorns suffered from what was blamed as faulty riveting. The ships would often pitch up out of the sea as far back as their bridge and would slam down hard, knocking men from their feet in the stokeholds and bridge.[10]

Jellicoe was annoyed by the meager radius of action for the class: 766 miles at 25 knots. Here, as well there was considerable variation: from 630 miles for Nereide to 925 miles for Cameleon.[11]

Armament

The gun armament used here was similar to that of the preceding Beagle class, although the 12-pdrs were no longer mounted in echelon. A similar scheme would carry forward into the Acheron class with minor variations in mountings and positioning of the 12-pdrs.

In late September, 1914, the Admiralty ordered that the guns on the Tribals and later classes were to be given loading lights, initially on temporary circuits.[12]

4-in Guns

The two 4-in guns mounted fore and aft were 4-in B.L. Mark VIII on P. III mountings with 120 rounds per gun.[13][14]

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 9,300 yards (14 degrees 44 arc minutes) at 2,225 fps.

The gear-worked sight had a range gearing contant of 54 and spiral-reading range dials were provided for 2225 fps, 1-in aiming rifle and .303-in aiming rifle. M.V. could be corrected by adjustable pointer to +/- 75 fps.

The deflection gearing constant was 50.69 with 1 knot equal to 3.05 arc minutes, corresponding to 2275 fps at 2000 yards. Drift was corrected by inclining the sight 2 degrees.

Sight lines were 10 inches above the bore, and 16 inches left and 15 inches right. Open sights and temperature correctors were provided.

The addition of depth charges obligated some ships to land their aft 4-in gun.[15]

Percussion firing gear to be fitted as soon as conveniently possible in dockyard was ordered for these guns in April, 1914.[16]

12-pdr Guns

The two 12-pdr guns were mounted on the port and starboard beams.[17]

They were 12-pdr 12 cwt Q.F. guns on P. V mountings with 100 rounds per gun, the same weapon as since the "Tribal" group.[18] The mountings could elevate to 20 degrees and depress to 10.

The sights were the only cam-worked 12-pdr sights in the Royal Navy, with range dials for 2150 fps, 1-in and .303-in aiming rifles. They could elevate to 20 degrees but their graduations ended at 19.25 degrees (8100 yards full charge). MV was corrected by adjustable pointer, +/- 100 fps.

Deflection gearing constant was 43.76, with 1 knot equalling 3.76 arc minutes, corresponding to a muzzle velocity of 2197 fps at 2000 yards.

Drift was corrected by inclining the sight 2 degrees. Sighting lines on the left were 10.25 inches above the bore and 10 inches left. The trainer's sighting lines were 12.25 inches above the bore and 10 inches right. His sight could be used as a free sight. Open sights were provided (for the layer at least), but there is no sign of temperature correctors.

In late 1913, the P. Mark V and VI gun mountings had percussion firing gear ordered for them.[19]

Torpedoes

Two single 21-in tubes on the centre line, firing the Mark II torpedo.[20]

Other Weapons

In July 1912, Alarm had an explosive sweep fitted with an electrically-fired charge. In May 1918, Nymphe had sweep gear, two depth charge throwers and 4 stern chutes with 12 charges. In August, 1918, Brisk had two depth charge throwers, eight carriers, one runner and 23 charges. Paravane equipment was landed to compensate for this 7.5 tons of added weight.[21]

Depth charges were added during the war to many of the ships, requiring some to surrender their aft 4-in gun.[22]

Fire Control

By 1915, at least, these ships also had fixed voice pipes installed between decks with the last lengths being flexible (one voice pipe for gunnery, one for torpedoes) fitted between bridge and guns, torpedo tubes, and searchlights. A third voicepipe, entirely flexible, ran from bridge to the forward gun.[23]

Instruments

By 1920, the ships in Acorn to Laforey classes had Wise Pressure Telegraphy Systems in place to support fire control.[24]

Rangefinders

A 1-m base rangefinder was supplied to all destroyers of the "Tribal" class through "L" class around 1916, but this was later withdrawn.[25]

Torpedo Control

Electrical Instruments[26]
found in most or all "Acorn" class destroyers

The ships had a single sighting position located high up in the centre of the bridge, which required them to thus have only a single set of firing pushes or keys as well as keys for operating a buzzer at the forward torpedo mount and a rattler at the aft mount.[27]

The data instruments used were electrical. A single Mark I deflection transmitter at the control position, and separate order transmitters and keys, one for the forward tubes and one for the aft. Each torpedo mount had a combined receiver for these signals.[28]

See Also

Footnotes

  1. Conway's All the World's Fighting Ships 1906–1921. p. 74.
  2. Annual Report of the Torpedo School, 1916. p. 87.
  3. Conway's All the World's Fighting Ships 1906–1921. p. 74.
  4. March. British Destroyers. pp. 115.
  5. Admiralty Weekly Order No. 184 of 24 July, 1914.
  6. Admiralty Weekly Order No. 454 of 6 Oct, 1914.
  7. The Technical History and Index, Vol. 4, Part 34. p. 11.
  8. March. British Destroyers. p. 109.
  9. March. British Destroyers. p. 113.
  10. March. British Destroyers. pp. 113-114.
  11. March. British Destroyers. p. 115.
  12. Admiralty Weekly Order No. 416 of 29 Sep, 1914.
  13. March. British Destroyers. p. 109.
  14. The Sight Manual, 1916. pp. 4, 88, 108, Plate 42.
  15. The Technical History and Index, Vol. 4, Part 34. p. 14.
  16. Admiralty Weekly Order No. 1045 of 24 Apr, 1914.
  17. The Sight Manual, 1916. pp. 4, 96, 108, Plate 46.
  18. March. British Destroyers. p. 109.
  19. Admiralty Weekly Order No. 718 of 12 Dec, 1913.
  20. Annual Report of the Torpedo School, 1909. p. 32.
  21. March.
  22. The Technical History and Index, Vol. 4, Part 34. p. 14.
  23. Manual of Gunnery, Vol. III., 1915., p. 150.
  24. The Technical History and Index, Vol. 4, Part 34. pp. 15-16.
  25. The Technical History and Index, Vol. 3, Part 23. pp. 31, 32.
  26. Annual Report of the Torpedo School, 1917. Plate 84.
  27. Annual Report of the Torpedo School, 1917. p. 211.
  28. Annual Report of the Torpedo School, 1917. p. 211, Plate 84. (C.I.O. 439/17.).

Bibliography


Acorn Class Destroyer
Acorn Alarm Brisk Sheldrake Staunch
Cameleon Comet Goldfinch Nemesis Nereide
Nymphe Fury Hope Larne Lyra
Martin Minstrel Redpole Rifleman Ruby
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