Boadicea Class Cruiser (1908)

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The seven scout cruisers of the Boadicea Class were completed at Pembroke Royal Dockyard between 1910 and 1913. Today, the class is often treated as three separate classes (two Boadiceas, two Blondes and three Actives) but contemporary documents almost always seem to discuss them collectively. There are, however some significant differences. Most notably, Boadicea and Bellona had just six 4-in guns, and the others carry eight or ten. The mountings also differ as indicated below.

Overview of 2 vessels
Citations for this data available on individual ship pages
Name Builder Laid Down Launched Completed Fate
Boadicea Pembroke Royal Dockyard 1 Jun, 1907 14 May, 1908 Jun, 1909 Sold 13 Jul, 1926
Bellona Pembroke Royal Dockyard 5 Jun, 1908 20 Mar, 1909 Feb, 1910 Sold 9 May, 1921

Binoculars

In September 1914, the ships were allowed six additional pairs of Pattern 343 Service Binoculars.[1]

Habitability

In 1912 and 1913, four Bastian Radiators were obtained for a temporary trial in warming the Officers' Cabins on the Upper Deck where radiators were not already present. Based on the satisfactory reports, these radiators were kept in place permanently.[2]

Boats

The ships were ordered in July 1914 to surrender their 13.5 foot dinghy unless they'd already returned their Balsa Raft – they were not to carry both.[3]

Rangefinders

In January 1914, it was reported that a rangefinder mounted on the fore upper bridge may have been unable to work properly when the ships were steaming at high speeds. Whether this was due to vibration or spray is not made clear.[4] At the same time, it was worried that a rangefinder mounted aft had a forward arc of view obstructed by boats.[5]

Armament

Guns

Boadicea and Bellona

This section sourced from The Sight Manual, 1916.[6]

  • six 4-in B.L. Mark VII guns on P. IV (Boadicea) or P. IV* Bellona – see next section) mountings

Boadicea's P. IV mounting could elevate to 15 degrees and depress to 10 degrees, but though its sight could match the 15 degree elevation, the range dial was only graduated to 8,500 yards (8.5 degrees) at 2,225 fps. This might have been in obeisance to the Admiralty's stated desire that giving a long-ranged gun to a light cruiser is a guarantee that it will go get in a gunfight and abandon its scouting duties.[Inference][Citation needed]

The gear-worked sights, the first F.T.P. models to be introduced, had a range gearing contant of 42.95 and spiral-reading range dials for 2850 fps, 1-in aiming rifle and .303-in aiming rifle. MV could be corrected (downward only) 200 fps by adjustable scale plate.

The deflection gearing constant was 61.7 with 1 knot equal to 2.74 arc minutes, corresponding to 2824 fps at 3500 yards. Drift was corrected by inclining the sight 2 degrees.

The layer's sight line was 16.8 inches above the bore, and 15 inches left. The trainer's lines were 16.8 inches above and 14.9 inches right.

The sight lacked a "C" corrector. A number of temperature scale plates corresponding to M.V.s varying by 25 fps could be shipped with an index facing the actual M.V..

Open sights do not seem to be in the drawing.

In October 1913, it was decided that the mountings should also have buzzer for their firing circuits.[7]

Blonde and Blanche

  • ten 4-in B.L. Mark VII guns on P. IV* mountings with F.T.P. sights.[8]

These ships had the same mountings as Bellona and some Bristol class cruisers.[9]

The mounting could elevate 15 degrees and depress 10 degrees, but though its sight could match the 15 degree elevation, the range dial was only graduated to 11.5 degrees (10,000 yards).

These cam-worked F.T.P. sights had range dials for 2750 fps, and 1-in and .303-in aiming rifles. M.V. could be corrected by adjustable pointer through +/- 150 fps.

The deflection gearing constant was 64.277 with 1 knot equal to 2.41 arc minutes, corresponding to 2800 fps at 2000 yards. Drift was corrected by inclining the sight 2 degrees.

The layer's sight line was 13.73 inches above the bore, and 15.85 inches left. The trainer's sight line was 15.08 inches above and 14.9 inches right.

The sight had a temperature correcting scale plate and a "C" corrector.

The layer had an open sight. The trainer's sight could be used as a free sight with a counterweight.

In August of 1913, Portsmouth Royal Dockyard was to supply head rests for these guns, to be fitted in the dockyard when the opportunity arose.[10] In October 1913, it was decided that the mountings should also have buzzer for their firing circuits.[11]

Active and Amphion

  • ten 4-in B.L. Mark VII guns[12] on P. IV** mountings[13]

The mounts could elevate 15 degrees and depress 10 degrees, but though the sights could match the 15 degree elevation, the range dials were only graduated to 11.5 degrees (10,000 yards).

These cam-worked sights had range dials for 2750 fps, and 1-in and .303-in aiming rifles. M.V. could be corrected by adjustable pointer through +/- 150 fps.

The deflection gearing constant was 64.277 with 1 knot equal to 2.41 arc minutes, corresponding to 2800 fps at 2000 yards. Drift was corrected by inclining the sight 2 degrees.

The layer's sight line was 13.73 inches above the bore, and 15.85 inches left. The trainer's sight line was 13.83 inches above and 14.9 inches right.

The sight had a temperature correcting scale plate and a "C" corrector.

These were likely F.T.P. sights, but there is no definite indication that they were.[Inference]

The layer had an open sight. The trainer's sight could be used as a free sight with a counterweight.[14]

In August of that 1913, Portsmouth Royal Dockyard was to supply head rests for the guns on Active and Amphion, to be fitted by the ships' artificers.[15]

Fearless[16]

  • ten (possibly just eight) 4-in B.L. Mark VII guns on P. VIII mountings with F.T.P. sights.

The mounts could elevate 15 degrees and depress 10 degrees, but though the sights could match the 15 degree elevation, the range dials were only graduated to 14 degrees (11,000 yards). It appears that no other ships carried this particular mount.

These cam-worked sights had range dials for 2750 fps, and 1-in and .303-in aiming rifles. M.V. could be corrected by adjustable pointer through +/- 150 fps.

The deflection gearing constant was 59.79 with 1 knot equal to 2.41 arc minutes, corresponding to 2750 fps at 2000 yards. Drift was corrected by inclining the sight bracket 2 degrees.

The layer's sight line was 12 inches above the bore, and 22.3 inches left. The trainer's sight line was 12 inches above and 18.25 inches right.

In addition to the M.V. corrector, the sight had a temperature correcting scale plate and a "C" corrector.

There was an open sight on both sides. No mention is made of a free sight.

Control Groups

"Scout" class Gun Control Groups[17]

In 1909, these were described as being similar to the Gem class, but the forecastle and poop guns could be controlled as separate groups or attached to the nearest broadside group on either side. The middle line guns could be connected to whichever side was desired.[18]


Directors

Main Battery

Secondary Battery

Torpedo Control

In 1907, Boadicea (and perhaps Bellona), Swift and the River class destroyers were to be equipped with Fore Bridge Firing Gear.[19]

Transmitting Stations

Dreyer Table

These ships had no fire control tables.[20]

Fire Control Instruments

Fire Control Circuits[21]

By 1909, both in this class were outfitted with the latest Vickers F.T.P. Fire Control Instruments (Mark I in Boadicea, Mark II in Bellona), marking a new wrinkle in equipment by replacing the Barr and Stroud equipment that had taken hold shortly after 1906. The equipment was fitted as follows:[22][23]

  • Range Transmitters: 3
  • Deflection Transmitters: 3
  • Range Receivers: 6
  • Deflection Receivers: 6
  • C.O.S.: 1
  • Vickers Fire Gongs: 6 with 3 keys

None of the ships had Target Visible or Gun Ready signals.[24]

Alterations

By November 1918, Boadicea, Bellona, Blonde and Blanche were fitted with rails for 66 mines. The torpedo tubes and guns removed when the mines were shipped could be placed back aboard with enough notice.[25]

See Also

Footnotes

  1. ↑ Admiralty Weekly Order No. 331 of 8 Sep, 1914.
  2. ↑ Admiralty Weekly Order No. 600 of 24 October 1913.
  3. ↑ Admiralty Weekly Order No. 131 of 10 July 1914.
  4. ↑ Admiralty Weekly Order No. 790 of 9 Jan, 1914.
  5. ↑ Admiralty Weekly Order No. 791 of 9 Jan, 1914.
  6. ↑ The Sight Manual. 1916. pp. 7, 87, 108, Plate 40.
  7. ↑ Admiralty Weekly Order No. 569 of 17 Oct, 1913.
  8. ↑ The Sight Manual. 1916. p. 86.
  9. ↑ The Sight Manual. 1916. pp. 86, 108, Plate 39.
  10. ↑ Admiralty Weekly Order No. 470 of 22 Aug, 1913.
  11. ↑ Admiralty Weekly Order No. 569 of 17 Oct, 1913.
  12. ↑ The Technical History and Index, Vol. 4, Part 36. p. 4.
  13. ↑ The Sight Manual. 1916. p. 86.
  14. ↑ The Sight Manual. 1916. pp. 86, 108, Plate 39.
  15. ↑ Admiralty Weekly Order No. 470 of 22 Aug, 1913.
  16. ↑ The Sight Manual. 1916. pp. 81-82, 108, Plate 35.
  17. ↑ Handbook for Fire Control Instruments, 1909. Plate 54.
  18. ↑ Handbook for Fire Control Instruments, 1909. pp. 51-52.
  19. ↑ Annual Report of the Torpedo School, 1907. p. 31. Its design was detailed in Annual Report of the Torpedo School, 1906, p. 28.
  20. ↑ Handbook of Captain F. C. Dreyer's Fire Control Tables, 1918. p. 3.
  21. ↑ Handbook for Fire Control Instruments, 1909. Plate 52.
  22. ↑ Handbook for Fire Control Instruments, 1909. pp. 57, 60.
  23. ↑ Annual Report of the Torpedo School, 1909. p. 148.
  24. ↑ Handbook for Fire Control Instruments, 1914. p. 11.
  25. ↑ Annual Report of the Torpedo School, Mining Appendix, 1917-18. p. 11. Plate 7.

Bibliography

  • 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.


Boadicea Class Scout Cruiser
Boadicea Group
  Boadicea Bellona  
Blonde Group
  Blonde Blanche  
Active Group
  Active Amphion Fearless  
<– Sentinel Class Minor Cruisers (UK) Bristol Class –>



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