REFERENCE DOCUMENTS & RESOURCES - OFFICIAL ADMIRALTY DOCUMENTS
ADM 1/8586/70: FINAL REPORT OF THE POST-WAR QUESTIONS COMMITTEE (1920)
Updated 16-Mar-2007

This document is a modern transcription of Admiralty record ADM 1/8586/70. It concerning naval lessons learned from the First World War. It was transcribed by David Chessum on behalf of the the Royal Navy Flag Officers 1904-1945 website. The original file is held at the The National Archives at Kew, London. This Crown Copyrighted material is reproduced here by kind permission of The National Archives.

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66

INDEX TO THE LIGHT CRUISER.

 

GENERAL REMARKS

Para .

Duties

1-4

Modern types

5, 6

Good endurance essential

7

Size of ship

8, 9

Gun power

10-14

6-in. gun type

15

“Hawkins” class

16, 17

Strengthening Cruiser Squadrons abroad

18

GENERAL CHARACTERISTICS

 

Report follows terms of reference

19

SPEED.

 

Relation of speed to endurance

20

Recommendation

21

Definition of deep load*

22

ENDURANCE

 

Recommendation

23

Definition of endurance

24

Distance table

24

ARMAMENT

 

Guns

25-33

Calibre of gun

25, 26

Protection against splinters

27

Pair-gun turrets

28, 29

Recommendation

30, 31

Shell rooms and magazines

32

Anti-aircraft guns

33

Torpedoes

34, 35

Searchlights and Star Shell

36, 37

DISPLACEMENT

38

PROTECTION

 

Above-water protection

39

Recommendation

40

Under-water protection

41

Watertight subdivision

42

Pumping and flooding

43

Magazine flooding

44

SPECIAL FITTINGS AND EQUIPMENT

Bridges, masts and controls

45

Conning tower

46

C.M.B. davits

47

Aircraft

48-51

Signalling and W/T arrangements

52

Rate of fuelling

53

Fire Main

54

Steering positions

55

Battleship section, paragraphs applicable

56

“HAWKINS” CLASS COMPLETING

57, 58

INDEX TO THE CONVOY CRUISER.

 

GENERAL IDEA

1-8


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67

 

LIGHT CRUISERS.

 GENERAL REMARKS.

1. Duties.- Of ships of the Light Cruiser type it is difficult to have too many; demands for their services arise constantly in war.

2. They are required for multifarious duties, in the execution of which there is no other type that can take their place effectively.

3. In the main area of the war they are required for scouting for the Fleet, for minor operations, supporting minelayers, aircraft carriers and destroyers.

4. They are required to patrol against raiders and to hunt them down.

5. Modern Types. – Our Light Cruisers may be divided into two main types – those mounting medium calibre guns of 6-in. or below, i.e. Light Cruiser classes culminating in the E Class, and those mounting heavy calibre guns of 7.5-in. or above, i.e. “Hawkins” class.

6. The following table shows details of the latest classes, as shown in C.B. 1543(1) and C.B.1543(A):-

 

Class.

H.P.

Speed.

Displacement

Endurance

Armament

Miles

Speed

Guns

Torpedo Tubes

Bristol

22,000

25

4800

5,800

10

(2 6-in.

(10 4-in.

2 submerged

Weymouth

22,000

25

5250

5,600

10

8 6-in.

2 “

Chatham

25,000

25½

5400

4,680

10

9 6-in.

2 “

Galatea

40,000

28½

3500

3,000

10

(3 6-in and

(4 4-in. or

(2 6-in and

(6 4-in.

4 twin A.W.

Early C.

40,000

28½

3750

3,500

14

4 6-in.

4 “

Later C.

40,000

29

4190

4,000

14

5 6-in.

4 “

D.

40,000

29

4650

4,500

14

6 6-in

4 triple A.W.

E.

80,000

(33 light

(32 deep

7550

4,300

14

7 6-in

(4 triple A.W. Arranged (for four quadruple A.W.

Hawkins

60,000

30

9750

5,400

14

7 7.5-in.

(2 submerged

(4 A.W.

Note.- Torpedo armament of ‘C” class varies; in some, submerged tubes are fitted and in others A.W. tubes.

7. Good Endurance Essential. – As a future war is likely to be oceanic, good endurance is essential; therefore that of our Light Cruisers should be increased.

8. Size of Ship. – In addition to good endurance their work involves good seaworthiness, ability to maintain speed under most weather conditions, good gun platform, and an armament capable of engaging enemy light cruisers.

9. Small ships of the size of the “C” or “D” class cannot possess all these qualities. At the same time it is necessary to keep down size and cost in order to obtain numbers.

10. Gun Power. – The gun power of a Light Cruiser should depend on the types of enemy vessels she will be called upon to encounter in performing her numerous and various duties.

11. With the Fleet, her gun armament is used to drive in the enemy’s screen in the course of her scouting duties, to beat off enemy light craft attacking the Fleet with torpedoes, and to enable her to press home torpedo attack on the hostile Battle Fleet.

12. In ocean warfare she has to deal with light cruisers, disguised raiders, cruiser submarines operating on the surface, and any other light craft that the enemy may employ to operate against our lines of communication and trade.

13. In the late war, superior gun power was the decisive factor in all cruiser actions that were fought to a finish, examples of which are Heligoland Bight, Coronel, Falklands, “ Sydney” and “ Emden,” and “Carmania” and “Cap Trafalgar.”

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68

 

14. The Germans quickly took to heart the lesson of the early actions and re-armed their light cruisers with 5.9-in. guns.

15. 6-in. Gun Type. – War experience having amply proved our 6-in. Light Cruisers, our policy should be to develop this type, which, although involving additional tonnage through increased endurance, still results in a moderate displacement and allows of numbers being built.

16. “Hawkins” Class. – In “Hawkins” class we have vessels which outgun enemy light cruisers now built or building, but these vessels are most expensive units which means fewer can be built.

17. Other Naval Powers may not take up the challenge thrown down by the “Hawkins,” a type which can be easily out-gunned in turn. The 9-2-in. is the most effective counter to the 7.5-in. and, although heavier, is not prohibitive in a ship of this size.

18. Strengthening Cruiser Squadrons Abroad. – If it is required to strengthen the Cruiser Squadrons on foreign stations, the older battle cruisers might be used.

 

GENERAL CHARACTERISTICS.

19. Report follows Terms of Reference. – The order in which the main naval requirements of the Light Cruiser are dealt with is similar to that in which they are given in our Terms of Reference.

 

SPEED.

20. Relation of Speed to Endurance. – Numbers entail small individual cost, which again entails moderate dimensions, and, since displacement cannot be materially increased and endurance must be, we are forced to accept a reduction in speed in order to provide additional fuel stowage.

21. Recommendation. – We therefore recommend an improved E class, reducing the speed from 32 to 30 knots at deep load condition, the weight and space saved by this reduction being devoted to oil stowage.

22. Definition of Deep Load. – By deep load condition is implied full sea-going complement and equipment of ammunition and stores, but with only two-thirds fuel on board. (See also para. 13, Battleship Section.)

ENDURANCE.

23. Recommendation. – We recommend an official endurance of 6,000 miles at a minimum speed of 14 knots, which is based on the distances of passages across the Atlantic and Pacific Oceans. (See table below.)

24. Definition of Endurance. – It should be noted that the “official endurance” is 15 per cent. less than the maximum distance which can be steamed on the fuel carried.

DISTANCE TABLE.

ATLANTIC.

Plymouth *    -    Halifax*

2,350

       “    -    Bermuda*

2,800

       “    -    Jamaica*

3,900

       “    -    Panama Canal

4,400

       “    -    Trinidad*

3,680

       “    -    Falkland Islands*

6,730

Cape of Good Hope*    -    Falkland Islands*

4,055

       “    -    Plymouth*

5,875

Sierra Leone *    -    Plymouth*

2,750

       “    -    Cape of Good Hope*

3,185

       “    -    Falkland Islands*

4,360

* British Possessions


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69

DISTANCE TABLE – continued.

INDIAN OCEAN .

Cape of Good Hope*    -    Mauritius*

2,250

       “    -    King George’s Sound ( West Australia)*

4,675

Mauritius *    -    Colombo*

2,100

       “    -    Singapore

3,325

       “    -    King George’s Sound ( West Australia)*

3,300

PACIFIC OCEAN

Singapore * - Yokohama

2,890

       “    -    Hong Kong*

1,460

Hong Kong*    -    Honolulu

4,950

Yokohama    -    Esquimalt*

4,220

Panama    -    Fiji*

6,290

Hong Kong*    -    Fiji*

4,430

Falkland Islands*    -    Wellington*

5,000

*British Possessions.

 

ARMAMENT.

GUNS.

25. Calibre of Gun. – Rapidity of fire, long range, large danger space and large burst effect are essential requirements, and the arguments for those have already been put forward in discussing the secondary armament of the Battleship (See Battleship Section, para. 58.)

26. We consider that for a Light Cruiser the guns should be the largest calibre which can be hand worked and still maintain rapidity of fire, and this we consider to be a gun firing a shell of 100 lb. The same gun has been recommended for the secondary armament of Capital Ships. (See paras. 56 to 62 of Battleship Section which deal with this question.)

27. Protection against Splinters. – At the Battle of Jutland the personnel in the open batteries of both “ Chester” and “ Southampton” suffered very severely, although the material did not suffer correspondingly; it follows that each gun position must be isolated and adequate protection against splinters provided for both guns’ crews, and ammunition supply.

28. Pair-Gun Turrets. – The policy of mounting guns in pairs presents many advantages and has already been dealt with in the Battleship Section, paras. 66, 68 and 71. These include:-

Economy in space and protection.
Simplicity of ammunition supply.
Reduction in supply parties.

29. In the “E” class seven 6-in. guns are mounted, five of which are centre line and two broadside, giving a broadside of six guns and three on extreme bow and quarter bearings. By mounting eight guns in pairs, superimposed, forward and aft, a broadside of eight is obtained with four on extreme bearings.

30. Recommendation. – We therefore recommend that eight guns firing 100-lb. shell be mounted in pairs in light splinter-proof turrets, which not only give protection in action, but also provide shelter to personnel, materiel and ammunition; the guns should have a range of 20,000 yds.

31. The turrets to be disposed in a similar manner as the 15-in. turrets in the “Queen Elizabeth” class, or as the 13.5-in. in the “Tiger.”

32. Shell Rooms and Magazines. – Each turret to have its own shell room and magazine, with a protected ammunition supply trunk, which should supply direct from the magazines and shell room to the gun-house; flash-tight arrangements should be fitted both top and bottom. (See also para. 71 of the Battleship Section.)

33. Anti-Aircraft Guns. – Provision to be made for two 3-in. anti-aircraft guns (or of calibre supplied to Battleships). A.A. machine guns should be supplied as well, arranged so that at least three will fire on any bearing.

 

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70

TORPEDOES

34. Your Committee has rejected the idea of a special torpedo cruiser, and regards the Light Cruisers and Destroyers as the torpedo vessels of the Fleet.

35. As the bulk of the evidence we have heard is against fitting submerged tubes in Light Cruisers, we consider that the maximum numbers of above-water tubes that the design of the ship permits should be mounted; we therefore recommend an armament of two quadruple above-water revolving torpedo tubes each side.

 

SEARCHLIGHTS AND STAR SHELL.

36. Two 36-in. searchlights, to be mounted on the centre line, well abaft the bridge and separated, to avoid destruction by one shell.

37. Star shell to be fired either from A.A. guns or special howitzers. (See Battleship Section, paras. 78 to 81.)

 

DISPLACEMENT.

38. We have been given to understand that the characteristics put forward can be obtained without exceeding the displacement of the “E” class, which we recommend as the limit of size of the Light Cruiser.

 

PROTECTION.

39. Above-Water Protection. – An increase in the weight of protection beyond that fitted to the “E” class involves a much larger vessel, and the whole idea underlying the type of light cruiser recommended is to restrict size in order to obtain numbers.

40. Recommendation. – In spite of the increased efficiency of projectiles over armour, we do not recommend any increase in the weight of protective plating as fitted to the “E” class.

41. Under-Water Protection. – No form of bulge protection is considered necessary for ships of this size, but the question of working in a partial torpedo bulkhead to protect vitals should be considered in future design; it might be possible to fit such a bulkhead in wake of the main armament magazines and shell rooms.

42. Watertight Subdivision. – The watertight subdivision in the present Light Cruisers has proved satisfactory and subdivision on these lines should be adhered to.

43. Pumping and Flooding. – as at present fitted to Light Cruisers is adequate.

44. Magazine Flooding. – The same arrangements as recommended for battleships to be fitted (see Battleship Section paras. 197-202).

SPECIAL FITTINGS AND EQUIPMENT.

45. Bridges, Masts and Controls should be of the type finally decided on after the Fire Control Committee’s recommendations have been tried at sea.

46. Conning Tower. – We do not consider a conning tower necessary, but protection against machine gun fire from aircraft must be provided for the navigating bridge.

47. Coastal Motor Boat Davits. – One pair of boat’s davits each side should be capable of hoisting the smaller type Coastal Motor Boat.

48. Aircraft. – The necessity for aircraft in large numbers being immediately available on the outbreak of war makes it essential that as many as possible should be carried by Light Cruisers themselves, especially as vessels on detached service cannot expect a carrier in attendance.

49. With the proposed arrangements of guns there should be ample space on the weather deck to allow a sufficient stowage for aircraft.

50. We therefore recommend that one revolving flying-off platform, abaft the funnels, with a hangar to contain at least two machines, be fitted.

51. As at present it may be necessary to fit ships on detached service with seaplanes, it is necessary to provide suitable hoisting in and out arrangements so that either aeroplanes or seaplanes can be carried at will.

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71

52. Signalling and Wireless Arrangements. – The present arrangements in Light Cruisers are considered satisfactory, and the disposition of signalling searchlights should be adhered to.

53. Rate of Fuelling. – We recommend that the oil fuel embarking arrangements of a Light Cruiser should enable fuel to be embarked at the rate of 300 tons per hour and at half that rate using her own pumping resources.

54. Fire Main. – We consider that the arrangement of the salt water fire main now fitted in light Cruisers is satisfactory.

55. Steering Position. – We consider that the steering positions provided in Light Cruisers are satisfactory.

56. Battleship Section Paragraphs applicable. – The following paragraphs fro the Battleship Section apply equally to Light Cruisers:-

176 Stowage of anchors.
177 and 178. Boats and rafts.
182 Deck plates
183 and 184. Electric cables and fittings.
185 Electric generators.
190 Galley.
191 Gas.
192 Heating.
194 Information on buoyancy, etc.
195 Multiplicity of control instruments.
196 Magazine cooling.
203 )
to ) Marking for identification purposes.
205 )
208 ) Model
214) Alternative conning position aloft.
215) Steering gear.
219)
to ) Watertight doors, hatches and valves.
224 )

 

“HAWKINS” CLASS COMPLETING.

57. In a letter, dated 19 th November 1919, your Committee submitted certain proposals on the reversion of the “Vindictive” to a Light Cruiser. We are still of opinion that the vessels of the “Hawkins” class now completing should be fitted to carry aircraft as stated in that letter.

58. We therefore recommend that for these ships the following arrangements for carrying aircraft should be made:-

To fit a hangar forward, as in “Vindictive,” in place of No. 2 7.5-in. gun.

Four Baby seaplanes of four fighter aeroplanes could be carried here and still leave space for fitting a workshop in the hangar.

A light steel deck from after funnel, extending about 60 ft. aft. with suitable hoisting-in arrangements; this provides stowage for two two-seater seaplanes, without displacing any of the main armament.

This involves a reduction of armament of one 7.5-in. gun (No. 2) leaving a broadside of five.

 

THE CONVOY CRUISER.

GENERAL IDEA.

1. An antidote to the cruiser submarine acting on our trade routes, or blockading off our ports, is a vessel of superior or equal gun power, slightly superior surface speed, equal endurance, good seaworthiness, and superior habitability.

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72

 

2. In considering the submarine cruiser your Committee saw that about 10 per cent. of her displacement was absorbed by machinery and fittings for under-water propulsion and diving. By using Diesel engines of slightly greater power n a surface vessel of the same displacement, the saving of weight could be utilised to obtain:-

Superior gun power,
Slightly superior speed,
Equal endurance,
Better habitability,
Good seaworthiness.

3. Such a vessel will require a smaller crew and, compared to the steam-driven surface ship, will save in weight of men and the stores and fittings necessary for them.

4. This idea can be expanded, as necessary, until these vessels are capable of fighting a surface light cruiser though, for the present, inferior to her in speed.

5. Good seaworthiness is essential, she will have to be specially designed and may have to be fitted with stabilising gyroscope.

6. We recommend that she should carry:-

Similar guns to the surface light cruiser, mounted on the centre-line, with proper control.
One anti-submarine torpedo tube on either beam.
One small seaplane scout.
Anti-aircraft pom-poms or machine guns.
The best submarine detection apparatus.
Long range wireless.
Depth charges.
10-in. signalling searchlight.

7. Such a vessel could use the seaplane for ascertaining the enemy’s movements and, with submarine detection ranging to two miles or more, could remain stopped for long periods while the seaplane is scouting.

8. She could relieve the armed merchant cruiser which was so much needed for trade duties.

END OF TRANSCRIPTION