REFERENCE DOCUMENTS & RESOURCES - OFFICIAL ADMIRALTY DOCUMENTS
ADM 186/349: PROGRESS IN NAVAL GUNNERY, 1938 EDITION
Updated 18-Oct-2007

This document is a modern transcription of a portion of Admiralty record ADM 186/349. It highlights the state of Royal Navy warship gunnery as of 1938. 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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START OF TRANSCRIPTION

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CONTENTS
Page
LIST OF PLATES
3
INTRODUCTION >4
PART I. - General Review 5

PART II. - Anti-Ship Gunnery

>26
Section A. - Battleships and Battle Cruisers
Section B. - Cruisers
Section C. - Aircraft Carriers
Section D. - Leaders and Destroyers
Section E. - Submarines
Section F. - Escort Vessels, Patrol Vessels, Minesweepers & Gunboats
26
36
52
54
74
77
PART III. Anti-Aircraft Gunnery 80

Section 1. - Long Range A.A. Gunnery
Section 2. - Close Range A.A. Gunnery
Section 3. - A.A. Fire from light craft
Section 4. - General

80
89
96
98
PART IV. - Shore Attack and Defense 102

Section 1. - Naval Bombardment
Section 2. - Coast Defence

102
112
PART V. - Material 114
Section 1. - Affecting more than one class of ship
Section 2. - Affecting particular classes of ship
114
117

A. - Battleships and Battle Cruisers
B. - Cruisers
C. - Aircraft Carriers
D. - Leaders and Destroyers
E. - Submarines
F. - Escort Vessels, Patrol Vessels, Minesweepers and Gunboats

117
118
121
121
122
122

Section 3. - A.A. Material

123
APPENDIX I. - Cruiser Spotting Rules 134

Section 1. - Direct Spotting Rules
Section 2. - 6in. Cruiser Air Spotting Rules

134
136
APPENDIX II. - H.M.S. "Galatea" - Spotting Plot in Transmitting Station 138
APPENDIX III. - Comparative Analysis of the Results achieved by Mediterranean Fleet Trend Rules, the "Admiralty" Zig-zag, and Standard Rules for Destroyers 139
APPENDIX IV. - Destroyer Spotting Rules, 1938 141
APPENDIX V. - Diagrammatic Control Arrangements in Modern Cruisers 144
APPENDIX VI. - Summary of the Experimental Firings carried out by H.M.S. "Newcastle" at Shoesburyness during October, 1937 145
APPENDIX VII. - Gunnery Practice by H.M.S. "Hood," H.S.B.P.T., 30.6.37 148

 

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LIST OF PLATES

No.

To face Page

1. - Aircraft v. Ship - Summary of available Data Long Range A.A. Targets

2. - Aircraft v. Ship - Summary of available Data Close Range A.A. Targets

3. - H.M.S. Galatea - Spitting Plot in Transmitting Station

4. - Birmingham, Glasgow and Sheffield - Transmission Control - Magslip

5. - Belfast and Edinburgh - Transmission and Control - Magslip

101

101

138

144

144

At end of book -

6. - Nelson and Rodney, S.S., 16-in., Mark I, Throw-off, H.S.B.P.T., and M.A.C. at Centurion.

7. - Nelson and Rodney, Pair Ship Concentration, 16-in., Mark I, Throw-off H.S.B.P.T. and M.A.C. at Centurion

8. - Battleships and Battle Cruisers, S.S., 15-in., Mark I, as above

9. - Battleships and Battle Cruisers, Pair Ship Concentration, 15-in., Mark I, as above

10. - Battleships and Battle Cruisers, Three-Ship Concentration, 15-in., Mark I, as above

11. - Battleships and Battle Cruisers, Four-Ship Concentration, 15-in., Mark I, as above

12. - Nelson and Rodney, Secondary Armament, 6-in., Mark XXII, Throw-off H.S.B.P.T. and Centurion Firings

13. - Battleships, Secondary Armament, 6-in., Mark XII, as Plate 12

14. - Cruisers, S.S., 8-in., Mark VIII

15. - Cruisers, S.S., 6-in., Mark XXIII, Throw-off, H.S.B.P.T. and Centurion Firings.

16. - Cruisers, S.S., 6-in., Mark XII, as Plate 15.

17. - Cruisers, Pair-Ship Concentration

18. - Cruisers, Three-Ship Concentration

19. - Leaders and Destroyers, S.S., Q.F., 4.7-in., Q.F., Mark IX

20. - Leaders and Destroyers, Concentration, 4-in., Q.F., Mark V, and 4.7-in., Q.F., Mark IX

21. - Analysis Chart for Gunnery Practice by H.M.S. Hood (See Appendix VII)

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INTRODUCTION

General information and instructions for practices were issued in Admiralty letter T.S.D. 45/38/G of 10/3/38.

2. Annual Reports from Commanders-in-Chief should reach the Admiralty not later than the 31st December, 1938, those from the Home, Mediterranean and China Fleets in quadruplicate, and from other Commanders-in-Chief and Flag Officers of squadrons in duplicate.

3. Drawing up the reports in the form of "Progress in Naval Gunnery" has been of great assistance in compiling this book ; tables of statistics, however, are not required.

4. Certain minor changes in the arrangement of the book have been made in this edition. The part previously devoted to "Gunnery in Foreign Navies" has been discontinued, and items of interest on this subject will be published in future in the "Monthly Intelligence Report."

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PART I
GENERAL REVIEW

SUMMARY OF YEAR'S WORK

The international situation had its effect on practice programmes, and hindered progress throughout the year.

2. The Home Fleet's taking over the duties on the Coast of Spain during Februrary, afforded the Mediterranean Fleet their only opportunity of concentrating at Malta. On return to their station after the Coronation Review, patrols in connection with the Nyon-Paris Agreements caused dispersion of squadrons and the cancellation of the autumn practice programme of efficiency tests and "Queen Bee" firings. The Home Fleet destroyers were also required for these patrols, and could not take part in the autumn firings at Centurion.

3. Duties on the Spanish coast interefered withe Home Fleet programmes during all practice periods, but some ships not affected by these were able to make good progress.

4. Ships on other stations, except China in the latter half of the year, have had a less interrupted year than in 1936.

5. Frequent changes of personnel, due to the expansion programme have had increasing effect on individual ship efficiency, and have made the interruption in programmes more seriously felt than otherwise they might have been.

6. To some extent these difficulties have been offset by Centurion being available in the autumn for the Home Fleet, and by the provision of the high speed battle practice target in the Mediterranean.

7. "Queen Bee" firings did not suffer as much as other practices, and both the Home and Mediterranan Fleets carried out these firings in two periods during the year.

8. Barrage firings from anti-ship guns were carried out by Nelson and Rodney, the 6-in. being used to augment the long range A.A. fire on the same target. This is dealt with more fully in Part III.

9. Importance is attached to the development of barrage fire from anti-ship guns in defence of the fleet against close range air attack on targets other than those being engaged by the A.A. armament.

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Principal Object for 1938 Practices

10. The importance of the investigation of control procedure and spotting rules still predominates, and no new problems should be undertaken. Practices during 1938 are to be devoted to consolidation of recent experience in these matters, and to attaining single-ship efficiency. In this connection attention is called to C.B. 3001/37, page 15, paragraph 35.

Competitive Firings

11. No results of competitive firings have been received during the year, and the Commander-in-Chief Mediterranean, has put these practices in abeyance for the following reasons:-

(i) The investigation of control problems and spotting rules make it undesirable to allocate ammunition to this type of firing.

(ii) These firings must be of the set piece type, and should, therefore, not become the most important practice of the year to which they tend by reason of the award of a cup.

Secondary armament competitive firings, however, will be continued as opportunities occur, as these arguments do not apply to them with such force.

12. To provide the competitive incentive in maintaining the standard of gunnery, a system of awarding outwardly visible efficiency emblems, has been adopted throughout the Mediterranean Fleet, and the Commander-in-Chief is satisfied that this scheme fully achieves its purpose. He has also under consideration the award of the gunnery cups to the ships which prove themselves to be the most efficient in their squadron during the course of the year.

The proposal for the award of the cup is concurred in. The scheme of awarding efficiency emblems, however, has recurred from time to time in the past, but the arguments against it have won the day. It is desired to obtain the opinions of the other fleets on this subject before expressing any opinion as to its general adoption.

Efficiency Tests

14. Comprehensive efficiency tests have again been carried out by the 8th Cruiser Squadron; and others of a somewhat less elaborate nature by various ships on other stations.

15. Great importance is attached to this type of exercise, as it not only provides thorough and realistic training in all the ship's action functions, but gives the senior officer of a squadron an opportunity to test the fighting qualities of the ship while he himself is on board.

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16. Apart from the valuable experience obtained in general training, the following points from efficiency tests carried out are of particular interest:-

(i) hat if the expensive alternatives provided in the gunnery equipment are to be effective, a higher standard of knowledge of them, and more practice in their use, are required by the personnel generally, than is at present achieved in the majority of ships.

(ii) Due to too much supervision in other practices and drills a rating in charge of quarters showed lack of confidence in his duties in an efficiency test when there could be no supervision.

(iii) Altering course at high speed with full rudder causes so much falling off in gunnery accuracy that the amount of rudder used should be limited to the minimum necessary to achieve the tactical object.

Some more details of the 8th Cruiser Squadron Efficiency Test are given in Part II, Section B.

Prolonged Firings

17. Full advantage has been taken of the additional ammunition allowance for these instructive and usually interesting practices.

During 1937 instructions were given that prolonged firings were no longer to be considered as slowly a test of material, and the introduction of control problems, in particular the investigation of new spotting rules, has added greatly to the experience obtained.

18. The outstanding practice of this nature was a 30-rounds per gun, full charge, 16-in. firing, carried out by Rodney in November. All but 8 rounds of the ammunition allowed were expended, and all guns were in action at the end of practice. The Commander-in-Chief, Home Fleet, remarks that full confidence can now be felt in these turrets when in the hands of experienced crews.

19. The 6-in. triple turrets in the Southampton class have also been proved thoroughly reliable in a prolonged firing. Some details of these and other prolonged firings are given in Part II.

Concentration Firings

20. The difficulties of maintaining individual ship efficiency have left few opportunities for concentration practices, and little progress has been made with problems in this connection. The following are some of the most important lessons noted:-

(i) The courses and relative positions of firing ships and target should be so arranged that the amount of, and variations in, the range and P.I.L. corrections will afford a realistic test of the ability of ships to concentrate under these conditions.

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(ii) Undetected errors in the P.I.L. correction, and irregular salvo intervals, indicate that sufficient attention is not always paid to the instructions on page 100, in C.B. 3026.
(iii)  If aircraft spotting is in use, it is better that the W/T rating in the control position of the consorts should read the aircraft reports, rather than the G/C signals from the master ship.

Large Scale Fleet Firing

21. The staging of a large scale fleet firing with air spotting has been under consideration for some years, and it was hoped that it might be carried out during the spring of this year, 1938. Other commitments, expansion, and the reconstruction programme have necessitated postponing this battle exercise for another year.

22. It is important, however, that the investigation of the problems involved should not be put off any longer if this can possibly be avoided, and it has been decided that this battle exercise will be carried out in 1939, unless unexpected circumstances arise.

23. It is therefore appropriate to give a brief outline of the type of practice visualised, and the specific points to be investigated.

Type of practice

The combined Battle and Battle Cruiser Squadrons of the Home and Mediterranean Fleets, deploying into action against two divisions represented by two lines of four or five battle practice targets, towed probably by Iron Duke and Centurion. Subsidiary cruiser actions at high speed battle practice targets may be included.

Points to be Investigated

24. (a) Fire distribution and target identification without the use of counting signals and variations in the distribution of fire.

(b) Identification of the correct target by the spotting aircraft and the procedure necessary to ensure this.
(c) Communication routes for spotting aircraft, and whether confusion will arise with a large number of spotting aircraft operating over a fleet when deployed.
(d) Sending up and tuning in relief spotting aircraft.
(e) W/T organisation in battle.
(f) Comparison of methods of procedure and organisation when the two fleets differ.
(g) The full use of ammunition supply arrangements.

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25. The current annual allowance of ammunition for prolonged firings in the Home and Mediterranean Fleets will probably have to be allocated to this exercise, and possibly also that for the following year.

26. These details with some amplifying instructions were issued to the two Commanders-in-Chief in Admiralty letter N/T.S. D35/35/G of the 8th April, 1935, and it is desired that preliminary consideration should be given during the current year to the training and arrangements necessary for carrying out this exercise.

It is understood that this exercise has been discussed during the meeting of the two fleets in 1938.

Duties of Control and Spotting Officers. (C.B. 3001/37, page 11)

27. A desire to revive the lessons of war, as far as they are still applicable, and to encourage full use of the valuable equipment now fitted in the transmitting station, led to the issue of Admiralty letter PM/T.S.D./4/37/G of 28th April, 1937, on the organisation of the main armament control team in capital ships and cruisers, in which Commanders-in-Chief were asked to state their views on:-

(i) The division of duties in control positions.

(ii) The employment of additional observers.

(iii) The possibility of introducing a control officer's aid or some form of T.S. control of range spotting corrections.

28. Replies were received from several Flag Officers and Captains, as well as Commanders-in-Chief, and the views expressed considered in conjunction with previous experience, including that of war, allow the following principles to be enunciated:-

(a)  Continuous observation of fall of shot demands a degree of concentration which is incompatible with the successful application of other mental processes.

(b) For observation to be continuous more than one spotter must be employed so that alternative view points are available, to guard against failure from fatigue.

(c)  The control of fire of the main armament is the responsibility of the Gunnery Officer by virtue of his training and experience.

(d) The Control Officer should not be required to maintain continuous observation of the target.

(e)  An organisation which fails to make full use of all the "aids" available is not satisfactory.

29. Some variation in sea opinion exists as to how, and by whom the spotting orders should be applied. The majority view, which is concurred in, is that it is the responsibility of the Control Officer, working in the closest collaboration with the transmitting station.

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30. Reference in several reports to transmitting station control shows a welcome trend of thought towards taking full advantage of the valuable equipment installed there. Transmitting station control in its fullest sense would involve the Control Officer (Gunnery Officer) being stationed in the transmitting station, but for practical reasons it is preferred that the Control Officer should be able to see the enemy and full transmitting station control is therefore not favoured.

31. It is only in the transmitting station that all the information is available, however, and where the personnel are freed from the disturbances of noise and weather: in consequence an officer in the transmitting station is very well equipped to make a correct interpretation of the situation, and to suggest the appropriate application of the spotting rules. This is borne out by the desire on the part of Control Officers, who order the corrections from the control position, to duplicate in that position the graphical record already existing in the transmitting station, so that they can better appreciate the situation.

32. The correct solution is considered to be that the transmitting station should continuously appreciate the situation, and must keep the control officer informed. In some cases no doubt the control officer would forestall the advice from the transmitting station, but whether he gives specific orders or merely a general instruction, leaving the application to the transmitting station, is a matter for internal organisation. The latter method is preferred as freeing the control officer from the detailed work, but in this case he must satisfy himself that the desired corrections are properly applied.

33. This procedure will facilitate changing control positions, should the main control cease to operate, as the transmitting station can immediately supply the new control officer with all the information he requires. Also it, as anticipated, really close so-operation and understanding can be established between the control officer and the transmitting station, the need for a graphical plot in the control position will diminish, as the control officers gain confidence in the working of their transmitting stations. The spotting plot is deal with in more detail in paragraphs 38 to 40.

34. Although the rate has not been specifically mentioned, it must be remembered that the need for range corrections arises from errors in rte-keeping, and great importance is attached to the organisation of the inclination group in conjunction with that for the spotting group, to enable this element to play its full part in the control of fire.

35. There is general agreement that spotting should be carried out from a position aft, and one other position in addition to the main control. The result of spotting from outlying positions should show in the main control, and the transmitting station.

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36. It is desired that an organisation to implement the principles in paragraph 28 on the lines indicated in the foregoing, particularly paragraphs 32, 34 and 35, should be developed in all capital ships and cruisers fitted with a suitable plot in the transmitting station. The system should provide for a spotter-observer in the primary control position in addition to the control officer.

37. The following points, also raised in the reports, are under consideration, and any further information of decisions regarding them will be communicated later:-

(a) The fitting of fall of shot lamp boxes and re-arrangement of telephone groups for observer reports.

(b) The serious effect of frequent changes on the training of control personnel.

(c) The introduction of trained spotters whether officers or ratings.

(d) The serious lack of protection in the control tops of older ships.

In the meantime ships should make such local arrangements as are considered necessary to meet the requirements of (a) above.

Control Officer's Plot

38. Opinion at sea is now almost unanimous that there is a definite requirement for a control officer's plot aid in the form of a spotting plot in capital ships and cruisers. The majority want the plot in the transmitting station, but some still advocate its fitting in the control position.

39. The considerations in C.B. 3001/37, page 12, paragraph 17, however, still apply, and to these may be added the experience in Rodney's prolonged firing, when the scope of a plot of a convenient size for a D.C.T. proved too small for large initial corrections, and later when the plot became illegible due to soot from the funnel.

40. Capital ships and cruisers except those equipped with Mark V and VI Tables, have a suitable plot in the T.S., and from the foregoing paragraphs about the main armament control team, it will be seen that the aim should be to make this plot suffice instead of duplicating it in the control position.

The importance of telling the spotting officer, as salvoes are about to fall, the number of splashes to expect, has recently been emphasised in several reports. This is made easier by writing the number of guns fired on the plot against the time of firing.

The steps being taken to provide for the cruisers with Mark V and Mark VI Tables are dealt with in Part V.

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T.S Control of Inclination. (C.B. 3001/37, page 13)

41. The organisation employed in Nelson continues to give good results, and similar methods have also been found satisfactory in Rodney.

42. The fire control table for the new battleships is being designed to give facilities, including an inclinometer plot, for this method of controlling inclination (se Part V), but so far it has not been possible, owing to pressure on design staffs, to undertake either a plot or comparison instrument for existing ships.

43. A good deal, however, can be done from ships' resources, and by internal organisation, to develop improved methods of correlating all the information available, and reducing lag in applying the result.

44. The Commander-in-Chief, America and West Indies, is arranging for the 8th cruiser Squadron during the year to carry out trials of a system of T.S. control of inclination.

Remarks on the subject should be included in annual reports for 1938.

Realism in Practices

45. There is little to add under this heading, except that in high speed battle practice target firings the towing ship should be allowed the freedom of manoeuvre indicated in C.B. 3001/37, page 15, paragraph 37, within the limits of inclination between 50° and 130°. The point on this subject in C.B. 3001/37 should continue to be borne in mind.

Speed of Firing Ship. (C.B. 3001/37, page 15, paragraph 36.)

46. The increased speeds ordered by C.A.F.O. 352/37 have added greatly to the experience gained in practices. The effect of inadequate weather protection in control positions, and of the use of full wheel at high speed on the accuracy of fire, have been especially emphasised. High speeds are no doubt a contributory cause in any falling off of the results obtained during 1937.

Throw-off Firings

Reporting Fall of Shot

47. The use of the distinguishing letter, instead of the "T," is proposed, to avoid confusion in W/T reports of fall of shot in simultaneous throw-off firings. This is concurred in. Marking Fall of Shot

48. The Commander-in-Chief, Home Fleet, recommends the use of two rakes, mounted on separate turrets or control towers, and one kept set rigidly to a fixed range while the other is adjusted for

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the up to date range. The latter to be used for all fall of shot reports, and the results of both, corrected for the true range at the time of firing, to be compared for the purpose of eliminating marking errors in the subsequent analysis. When circumstances permit this method is recommended.

Photographic marking

49. The Captain, Excellent, remarks that in a throw-off concentration on the turning point of the target line, very accurate results were obtained by photographic marking, and he suggests that this method might be used again from a destroyer keeping station on the target ship, in a position 1,000 yards the other side of the fall of shot.

Photographic Records of Fall of Shot

50. When the inclination is not near 90°, the distance over or short, as measured from photographs, should be adjusted for the error (if any) in line, before plotting on the analysis chart.

Rangefinding

51. Several reports again emphasise the necessity for constant practice for rangetakers, and in one it stated that rangetakers should not be allowed to read off the range on either the internal scale or the range repeat on the E.E. gear.

52. Occasions on which firing has been possible while rangefinding was ineffective, and the frequent inconsistency of rangefinders have led to proposals to try:-

(i) Stereoscopic rangefinders of foreign manufacture; and

(ii) The strip image field for low angle rangefinders.

For (i) it is claimed that reports from other navies are good, and for (ii) that the heightfinders with strip image fields give more consistent results.

In spite of the results from previous trials, these proposals will be considered.

Initial Ranges for Opening Fire. (C.B. 3001/37, page 14, paragraph 33)

53. Although rangetakers frequently take anything up to three minutes to settle down to a reasonable spread and consistency, withholding fire, when circumstances permit, for periods of 20 to 30 seconds has in some cases provided a more accurate mean range with which to open fire. Trials of this procedure are to continue throughout the year.

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Inclinating

54. When the range is much in error the inclinometers cannot be relied on, but modern inclinometers can give very accurate results when provided with the best geometric range, and full use should be made of them under suitable conditions.

55. It follows that before hitting is established, enemy course reports from aircraft are of paramount importance. In the latter stages, reports of alterations of course should have equal priority with those of fall of shot.

Yawing of the High Speed Battle Practice Target

56. Experience shows that the high speed battle practice target will yaw on an average of up to ten degrees from the main course, which, owing to the difficulty of inclinating on this target, introduced an unrealistic element into rate keeping.

57. It has, therefore, been decided that where the free training of the inclinometer permits, inclinating may be on the towing ship. Allowance must be made for the difference in bearing, and for the time lag (approximately 11/2 minutes) of the target following the alteration of course of the towing ship. Aircraft should also report the towing ships' movements and their reports should be similarly treated.

Gyro and Director Firing

60. Director firing is still being used in preference to gyro firing, except on rare occasions, and the absence of T.I.C. gear is not sufficient reason for this.

61. One ship blames the illumination of the collimator graticule, but with the improvement in collimators there should be no difficulty for this reason.

62. Supply of T.I.C. gear will commence in July, and when fitted gyro firing is to be regarded as the primary method. In the meantime director layers are to be encouraged to fire by gyro when conditions are suitable.

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SPOTTING RULES

63. From the analysis of the year's practices carried out by all classes of ships, and remarks in the annual reports, the broad conclusions from present experience are:-

(i) The correct or incorrect application of any set of logical rules has greater effect on the results to be expected than the differences in the details of the set of rules used. From this it follows that simplicity is a basic requirement.

(ii) To obtain the best hitting results from any set of spotting rules, it is essential for the organisation to be such that the fullest use is made of all the aids in the fire control system. In particular the importance of accurate rate keeping as an adjunct to spotting must not be lost sight of.

(iii) The general requirement for some form of trend groups for single ship action at medium and long ranges, with direct or aircraft spotting, has been established.

(iv) Trend groups should not be used for concentration nor for single ship action at close range, nor at night.

(v) The standard principles, applicable to any rules, for finding deflection, finding range and regaining range are sound.

64. Progress has been made towards achieving uniformity in the rules to be used by the different types of ships, and a variety of recommendations towards this end and to improve details, have been received. These are dealt with in their appropriate sections in Part II, and where re-drafting of rules has been necessary, the new ones are published in the appendices.

Reporting Bad Shots

65. The successful application of any spotting rules, especially those in which a correction precedes each salvo, is seriously affected by bad shots, and the failure to report bad shots may cause such confusion that hitting will only occur by chance.

The vital importance of honestly reporting bad shots must be impressed on all director layers.

Application of Target travel Corrections

Range correction

66. From a detailed investigation of the theory of applying the change in target travel correction while the application of spotting corrections is also in progress, it is apparent that only a slight error will occur in one particular set of circumstances, if this correction is invariably applied.

67. It has therefore been decided, in the interests of simplicity, that the change in target travel correction for range is to be applied on all occasions of altering the enemy settings in all ships fitted with Admiralty fire control tables or Admiralty fire control clocks.

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Deflection Correction

68. Since the change in deflection correction is not cumulative, and the amount of the error in line of the fall of shot can be judged by direct spotting, the existing rules for "applying" and "not applying" this correction are to remain unaltered.

69. Annual reports, 1938, should contain remarks on these rules, and on the possibility of further simplification by including the deflection correction in the general rule "always apply."

Accuracy of Air Reports of Fall of Shot for Range

70. A collective analysis of aircraft fall of shot reports for all day firings is given below. The mean errors show an all-round improvement on those for 1936.

Signalled Report

No. of Observations

Percentage of Observations With Errors Less than 100 yards

1937 Mean Errors

1936 Mean Errors

KK

100

200

300

400

500

600

700

800

900

1,000 or over

521

532

507

435

346

185

190

87

67

18

15

Per cent.

83

86

76

66

45

35

33

32

21

38

13

Yards

57

52

69

85

117

149

170

186

192

167

206

Yards

68

72

81

101

137

178

190

257

194

229

252

71. The inherent tendency to "under-spot" has been less apparent, and in some cases the endeavour to avoid this has led to "under-spotting."

72. It is stated by the Commanding Officer, Glorious, that the erratic spreads lead to erratic spotting. While it is appreciate that erratic spreads may increase the observers' difficulties in judging the M.P.I., it is hoped that using the spread as a horizontal scale is in no way responsible for the erratic spotting. The instructions in C.A.F.O. 1753/37 should correct any tendency there may have been in this direction.

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73. That more accurate and consistent results can be achieved, is illustrated by the table below. This table gives the results obtained by one observer in all firings, spotted or witnessed by him, in the same period as that covered by the preceding table. It is noteworthy that, of the 86 observations recorded, 84 were spotted from a position on the line of fire, over or close to the firing ship.

Signalled Report

No. of Observations

Percentage of Observations With Errors Less than 100 yards

Mean Errors

KK

100

200

300

400

500

600

700

800

900

1,000 or over

12

23

19

10

6

2

3

-

5

2

4

Per cent.

100

100

96

80

83

100

100

-

40

50

0

Yards

22

39

42

70

63

95

35

-

53

88

100

Aircraft Spotting Comparisons of Mean Errors

The above diagram provides a graphical comparison of the mean errors shown in the two preceding tables.

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Aircraft Inclination Results

74. Only 42 reports of the enemy's course were made throughout all 1937 firings compared with 64 reports in 1936. The mean error of these reports was 5.1° (7.2° in 1936).

Aircraft Course Reporting

75. It is reported by observers that they find it extremely difficult to give accurate and prompt reports of the course of the high speed battle practice target, owing to the amount of yaw, and also to detect the moment at which it alters its course, due to the absence of any indication in the wake. Reporting on the towing ship they find relatively easy.

76. For these reasons and to give the observers more realistic practice, it has been decided that in all target firings aircraft are to observe on the course of the towing ship, leaving the adjustment for lag of the target in following the alterations of the course to the control in the firing ship.

These reports are of paramount importance before hitting has been established, and on subsequent alterations of course.

77. It is important that the observer should make the signal "enemy is altering course" (OPRT-OSTA) as soon as the kick in the wake is seen rather than waiting to signal the new course.

It should be noted that in reply to the signal GLT aircraft may report course or inclination.

Aircraft Reports of Large Spreads in Concentration Firings

78. Suggestions have been received for amplifying the signal to give a clearer indication to the master control officer when ships are not shooting together in concentration firings. It is considered that this situation is adequately provided for by the instructions S.P. 02159X.B., page 13, and a plain language message should be made free use of as necessary, even if it delays subsequent fall of shot reports.

Sighting at Long Range

79. As a result of a night firing on a bright moonlit night the Rear-Admiral (D) states that the Commanding Officer is faced with the following questions, if evasion is not the intention:- (a)  Closing on an appropriate bearing which will admit of identification without the use of illuminants; or (b)  Closing in to effective searchlight or star shell range before challenging; or (c)  Challenging outside illuminating range provided a range can be obtained.

- Page 19 -

80. Apart from the tactical situation and the urgency or otherwise of engaging all enemy vessels sighted, considerations which should be borne in mind are:-

(i)  Except at close range, the advantage may be with the ship which delays exposing the searchlight, since it provides an excellent ranging mark.
(ii) At long range, the searchlight may not provide sufficient illumination for ranging and spotting.
(iii) Spotting may not be possible without the use if illuminants.

From this he concludes that the provision of star shell which will be effective up to 10,000 yards is most desirable. The Commander-in-Chief remarks that more efficient star shell are necessary, and that a reduction of time of flight is more important than an increase of range.

81. The decision in all of these questions rests with the commanding officer, who must judge the situation on the information available, and the circumstances obtaining at the time. When the decision to attack has been made, illuminants should be used as freely as necessary to ensure hitting, without undue regard for the possible value they may be to the enemy.

82. Developments with Star Shell are given in Part V - "Material".

Alarm Procedure

83. The new procedure of reporting "ON" when on bearing ordered, and "TARGET" when the enemy is actually seen in the sights, proposed in Admiralty letter M. 04399/37 of 31st August, 1937, has met with general approval as far as it has been tried.

Before deciding that this procedure should supersede the old one, it is desired that it should be given further trial throughout the year.

84. In this connection the Commander-in-Chief, America and West Indies, say that ships should be prepared to open fire, training by Evershed, and laying on the horizon, if the director cannot see the target. Other opinions on this question are desired.

85. In one night firing at Centurion the alarm was given before Centurion has been sighted, and the next four minutes were devoted to ineffective sweeps with searchlights and star shell, both of which were outranged.

Under certain conditions, star shell with flashless charges may be used to search for an enemy ship whose presence is suspected, but the star shell should be set with the longest fuze, and searchlights

- Page 20 -

Must not be exposed until the enemy is located within their range. Considerations on the use of illuminants at night are given fully in C.B. 3001/1914-36, Chapter XI, in which paragraph 13 deals with a star shell search using flashless charges.

Estimating the Range at Night

86. A number of reports emphasize the errors that occur in estimating both the range for the night, and the range of the target when sighted. Common faults are failure to re-assess the range for the night as the conditions change, and to allow for variations in visibility in different directions.

87. Another frequent source of error in the initial range is not making sufficient allowance for the change in range between sighting and opening fire.

88. The drill at the clock used to overcome this in one ship is:-

Set the range for the night, own ship's settings, an estimated speed for the type of enemy likely to be encountered, and an inclination of 180 °.

At the alarm, start the clock, and as soon as possible report to T.S. "enemy going 'left' (or 'right')." The inclination is then set to 130° Left (or Right) respectively until a better estimation of the inclination can be given by the control.

89. For this drill it is claimed that, assuming a reasonably accurate range for the night, the range at open fire should be approximately correct or short, which is the best alternative. This drill appears sound, and should be equally suitable when the range is re-estimated, or a rangefinder range is obtained before opening fire.

90. It is apparent that much practice is needed in estimating range at night, and the fullest use of tactical exercises designed for this purpose is recommended. It is important in these exercises, night encounters, and firings, that individual control officers should compare their estimates of the range with the actual ranges at the time, or as soon as possible after the event.

Night Spotting Rules

91. One ship states that the probable error in initial range will make "up" corrections of 400 yards quite inadequate.

The Commander-in-Chief, Mediterranean, recommends that the present rule should not be altered, but that control officers must always be prepared to give bolder corrections in exceptional circumstances. This is concurred in.

92. Another suggestion is that the invariable use of 800 yards for "down" corrections will not always produce the best hitting results.

- Page 21 -

93. It is possible that, with improved methods of applying rate at night, a "down 400" correction would be sufficient if shots go over after straddling.

The following rules are, therefore, to be used for trial:-

(i) Finding range - Use 800 yard bracket.

(ii) Regaining range - Use single-step corrections of 400 yards.

Aircraft Spotting at Night

94. Aircraft spotting was employed in one 8-in. cruiser and one 6-in. cruiser night firing. Both firings were on dark nights and, in each the observer reported difficulty in seeing the splashes when not illuminated directly by searchlights or star shell. On the other hand, The mean errors of the fall-of-shot reports were only slightly larger than those obtained in day firings.

This confirms the view expressed in C.B. 3001/36, page 17, paragraph 30.

Rangefinder Control

95. This has been adopted as the primary method of control by night in the 1st Cruiser Squadron, backed up by observation of fall of shot only when the latter is certain. This method has been in use in destroyers for some time.

Any system of control at night, in all ships, should always allow for full use being made of rangefinder ranges when these are available.

Use of Illuminants. .(C.B. 3001/37, page 21, paragraph 67 et seq.).

Searchlights

96. Hood reports interference with the secondary armament directors caused by one S/L sweeping on forward bearings, due to the searchlights and directors being on the same level.

97. The disposition of searchlights, and the arrangements of sights are under consideration and the results of replies to Admiralty letter T.O. 715/36 of 28th April, 1937.

Information on developments in searchlights and searchlight control is contained in Part V.

98. Discussing methods of avoiding possible interference to the director in opening fire, the Commander-in-Chief, Home Fleet, suggests that the searchlight beam should not be exposed until salvos fall, and then it should be used if necessary to assist spotting.

99. On the other hand, the opinion has been expressed that all illuminants should be used until the all important rangefinder range is obtained, and that it should be the exception rather than the rule, for the searchlight shutter to closed before hitting is established.

- Page 22 -

100. Occasions will arise when the searchlight is not required, except for spotting, but the control will have to be very efficient to ensure the searchlight being effective immediately on exposing the beam, and if so it seems that it should be well enough controlled not to interfere with firing. However, the procedure should be borne in mind where difficulties are encountered.

101. In practices in which the towing ship directed a searchlight on the firing ship, some interference was caused to laying, and a great deal to spotting. Confirmation must await the fitting of a searchlight in Centurion, the development of which is now in hand.

102. In this connection it is pointed out that white or grey sails reduce the unrealistic difficulties in illuminating battle practice targets, and that such sails might be more representative of the colour of enemy ships likely to be encountered.

The Commander-in-Chief, Mediterranean, is investigating this problem.

Star Shell

Rate of fire

103. It is generally agreed that six salvos per minute from two 4-in. guns is sufficient to produce effective illumination. In some cases this is qualified to the extent that four guns may be needed for the initial salvos, which should be fired as quickly as possible, and that, as nothing less than the maximum efficiency under all conditions is acceptable, a higher rate of fire up to eight rounds per minute should be used as freely as required. When the deflection has been found six salvos per minute should be regarded as the normal rate of fire.

Time of Burning

104. The Vice-Admiral Commanding, Battle-Cruiser Squadron, recommends that, since star shell are only really effective during the middle third of their descent, the time of burning should be reduced to 10 seconds with a corresponding increase in intensity of illumination.

105. While it is agreed that this would not necessitate a higher rte of fire, it must make deflection keeping more difficult, and unavoidable inaccuracy, particularly with a high bearing rate, would more quickly render the star shell completely ineffective. This recommendation is not concurred in.

Use of Star Shell to show up Movements of an Enemy burning a searchlight. (C.B. 3001/37, page 23, paragraph 75.)

106. Little more experience has been gained on this point, but the evidence from a night target firing shows that the towing ship's searchlight may make star shell ineffective on a battle practice target. More information is required.

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Night Tracer

107. There is a demand from some quarters for night, tracer fitted, service ammunition to assist in distinguishing own fall of shot, when more than one ship is engaging the same target, and in spotting for line in a single ship action, when the glare of the enemy's searchlight may otherwise make this practically impossible. Night tracer for base fuzed shell are sill in the process of being developed, and the policy with regard to the supply and use of night tracer is as stated in C.A.F.O. 557/37.

Night Look-Out Teacher

108. Good value in training night look-outs has been obtained by the Mediterranean Fleet by the introduction of the night look-out teacher.

Use of A.A. Armament for Low Angle Fire at Night

109. This problem assumes more importance with the increase in long range A.A. armaments, and is still under consideration in the Admiralty.

110. Reports from sea indicate that serious limitations may be imposed on the engaged side from the blast from after turrets on forward bearings, and on the disengaged side by the difficulty I providing illuminants without silhouetting the ship, to the advantage of the principal enemy.

111. It is desired to pursue this problem, however, and information is required on the organisation of the control necessary to prevent these two functions conflicting, and to avoid confusion when changing from one to the other.

Points to be remembered are:-

(i) Elaborate equipment and complications to existing control gear cannot be accepted.

(ii) The existing arrangements for control of star shell are efficient, and careful consideration is required before making a change.

(iii) All the A.A. guns on the engaged side may be required for initial star shell salvos, and subsequently is may be desirable to keep one half in reserve for this purpose, while the other maintains illumination.

(iv)  Restrictions of the arcs of fire of a main armament turret, cannot be accepted to enable the A.A. mounting to remain manned.

(v)  Ammunition supply arrangements must allow for either type of star shell being instantly available, and must guard against mistakes in the type used.

(vi)  The engagement of more than one target on one side should not be considered.

- Page 24 -

112. These limitations would appear to reduce the problem to one of how best to employ the A.A. armament on the disengaged side at night, and it is desired that investigations should be more particularly devoted to this aspect.

Targets

113. The first of the 145-ft. high speed battle practice targets will shortly be available for trial in the Home Fleet.

The smaller target, although well reported on generally, is still criticised by both main fleets as being too difficult for either direct or aircraft spotting at long range. The longer sail and second mast have not produced much improvement in this respect.

114. The Centurion will be available for a full programme this year for both the main fleets.

115. The D/C motor boat for use as a target, or for towing a special target raft will shortly carry out trials.

Defence against M.T.B.s

116. Delay in supply of material has hindered progress with this problem. A pom-pom director, Mark II, was shipped to Excellent, in August, 1937, and photographically analysed trials against M.T.B. 08 were commenced.

117. Results so far have been disappointing, and owing to the impossibility of reproducing the effect of spotting, the trials have been inconclusive. When the D/C motor boat and target raft are available, this obstacle will be removed.

POINTS ON WHICH INFORMATION IS REQUIRED WHEN
OBTAINABLE FROM NORMAL PRACTICES

G.1. - Communications required for direct spotter-observers when more than one is employed (paragraph 37(a)).

G.2. - The suitability of existing plots in transmitting stations for assisting the application of spotting rules (paragraphs 38 to 40).

G.3. - Transmitting station control of inclination, and the suitability of existing facilities (paragraphs 41 to 44).

G.4. - Accuracy of marking in throw-off firings (paragraphs 48 and 49).

G. 5. Initial range at opening fire (paragraph 53).

- Page 25 -

G.6. - Inclinating on the towing ship (paragraphs 56 to 59 and 75 to 77).

G.7. - Invariable application of target travel corrections (paragraphs 66 to 67).

G. 8. - Night alarm procedure (paragraphs 83 and 85).

G. 9. - Estimating the range at night and drill in the transmitting station for opening fire (paragraphs 86 to 90).

G. 10. - Night spotting rules (paragraphs 91 to 93).

G. 11. - Rangefinder control at night (paragraph 95).

G. 12. - Use of star shell for showing up movements of an enemy using a searchlight (paragraph 106).

G. 13. - Use of A.A. armament for L.A. fire at night (paragraphs 109 to 112).

- Page 26 -

PART II
ANTI-SHIP GUNNERY

SECTION A. - BATTLESHIPS AND BATTLE CRUISERS

16-in. Prolonged Firing by "Rodney"

Rodney was allowed 30 rounds per gun with full charges with the primary object of testing modifications in the shell handling rooms and the performance of new 8-ton obdurating pages.

2. Full advantage was taken of the opportunity to exercise control positions, shifting target and quarters firing, and the practice was conducted in four phases with these results:-

Phase

Control.

Full Salvos Per Minute

Output Per Cent

Spread

Hits/Gun/Minute

1.

B.P.T. Main Control Aircraft spotting

1.63

86

390

0.1147

2

H.S.B.PT. Main Control Direct Spotting

1.95

89

285

0.0803

3

B.P.T. Main and lower Control Direct Spotting

2.00

97

262

0.0823

4

H.S.B.P.T. Main Control and Quarters firint. Direct Spotting

2.2

1.7

100

-

280

-

0.0275

-

3. Conditions for rangefinding and spotting at the beginning were very difficult, but the visibility improved as the firing progressed, and from the latter part of phase 3 onwards a fair rangefinder plot was obtained.

Fire was opening on a D.C.T. range more than 3,000 yards short, and three doubles were required to find the target as the aircraft could not estimate the distance until salvos about 1,000 yards short were obtained. In no phase were the rangefinders successful in putting the opening salvos on the target, and this with four separate phases is largely responsible for the somewhat disappointing hitting results.

- Page 27 -

4. The outstanding feature of the practice is the progressive improvement in the rate of fire and output, with all guns in action at the end. Most of the loss of output occurred at two guns, where at one a minor interlock failure indirectly resulted in double loading a cordite hoist, causing 12 salvos to be missed; and at the other scored breech threads caused 4 salvos to be missed.

5. The modified loading gear and the obdurating pads proved entirely satisfactory. OF the 270 rounds allowed, 262 were fired, but the practice was not a searching test of endurance, as intervals of up to two minutes occurred between phases, and at one time there was a delay of ten minutes waiting for a clear range.

15-in. Prolonged Firing by H.M.S. "Hood"

6. Although the range was on the short side (14,500 - 9,500) for 15-in. guns, this practice was a realistic one, and a good test of the control as well as the endurance of the turrets.

7. Owing to the initial position taken up, Hood was somewhat restricted in alterations of course, but the yaw of the ship at 26 knots taxed the layers and trainers, and alterations of course and yaw of the target, simulating a cruiser taking avoiding action, provided the control with a problem requiring careful co-ordination of all aids. Aircraft spotting was used.

8. Of 132 rounds allowed, 123 were fired in 41 salvos with these results:-

Equivalent F.G. Salvos Per Minute

Output Per cent

Spread

Hits/Gun/Minute

1.95

78.84

172

0.173

The loss of output was largely due to mistakes in drill, little time having been available for working up since last docking.

9. The conditions were good, and the rangefinders, except for "Y," where vibration was bad, produced excellent results, and the target was found with the second double.

10. The practice was generally satisfactory and most valuable experience was gained, but results could have been improved if more notice had been taken of the frequent good suggestions from the transmitting station.

- Page 28 -

11. The following tables show the results obtained in full calibre practices of which reports have been received in 1937. the figures in brackets indicate the results obtained in 1936.

SINGLE SHIP PRACTICES

Day

Target and Number of Practices

Mean Range

Full Gun Salvos Per Minute

Output Per Cent

Spread

Hits Per Gun Per Minute

Normal -N
Trend -T
Aircraft -A

16-in.

145-ft B.P.T. -2

17,700

(20,900)

1.6

(1.59)

94.44

(95.9)

276

(355)

0.057

(0.109)

A

H.S.B.P.T. -1

16,000

(15,500)

1.95

(1.74)

93.4
(91.7)

326

(244)

0.390

(0.079)

A

Throw-off -2

17,900

1.34

-

-

0.031

A

6-in with M.A.C.

145-ft B.P.T. -2

11,100

(15,200)

2.20

(2.18)

-

-

0.370

(0.230)

A

Throw-off - 2

13,600

(12,800)

1.57

(2.05)

-

-

0.050

(0.071)

A

Centurion - 2

14,800

2.34

-

-

0.095

N

15-in

145-ft B.P.T. -6

14,000

(14,400)

2.02

(1.85)

91.88

(80.5)

253

(200)

0.220

(0.190)

N

H.S.B.P.T. - 3

13,400

(20,250)

2.07

(1.82)

88.6

(100.0)

258

(213)

0.110

(0.000)

N

H.S.B.P.T. - 6

14,400

1.90

88.5

182

0.126

A

Throw-off - 3

15,700

(15,100)

1.86

(2.01)

-

-

0.073

(0.065)

A

Throw-off -1

14,000

1.91

-

-

0.064

N

6-in with 15-in M.A.C.

145-ft B.P.T. -4

9,260

2.84

-

192

0.292

N

H.S.B.P.T. - 1

9,500

2.31

-

148

0.170

A

Night

16-in

145-ft B.P.T - 3

4,200

0.645

(1.06)

100.0

(92.5)

273

0

(0.122)

N

15-in

145-ft B.P.T -6

3,100

(3,300)

2.38

(1.15)

100.0

(93.7)

195

0.459

(0.390)

N

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CONCENTRATION OF FIRE

12. Master Ship Control (G.M.S.)

Target and Number of Practices

Mean Range

Full Gun Salvos Per Minute

Output Per Cent

Spread

Hits Per Gun Per Minute

Normal -N
Trend -T
Aircraft -A

15-in Pair Ship

H.S.B.P.T. -1

16,200

(13,600)

1.64

(1.63)

97.5
(100.0)

307 - Bar

260 - QE

799 - Div

}

} 0.021

}

(0.077

AT

Individual Ship Control (G.I.C.)

(No firings carried out during 1937)

RANGEFINDING

13. Results obtained in 1936 are shown in parenthesis.

Armament

Error

Average Error of 1st Salvos

Percentage Of 1st Salvos to Straddle

Mean Range

At Open Fire

At Cease Fire

16- in

90

(368)

275

(300)

190

(364)

60

(17.6)

154

(157)

6-in with 16-in M.A.C.

317

107

250

16.7

132

15-in

380

(316)

220

(172)

480

(227)

20

(25)

143

(142)

6-in with 15-in M.A.C.

170

75

150

33

093

- Page 30 -

INCLINATING

14. Results obtained in 1936 are shown in parenthesis.

Armament

Average Error

Observed Alterations of Course

Inst

Air*

Used

Inst

Air

Per cent

Lag Secs

Per cent

Lag Secs

16-in.

5.0

(11.5)

4.8

(10.2)

7.3

(10.3)

94.0

(50.0)

12.1

(60.0)

-

-

6-in. with 16-in. M.A.C.

7.8

10.0

14.2

-

-

-

-

15-in.

10.3

(5.6)

4.5

(50.)

904

(10.8)

86.5

(76.5)

42.0

(31.0)

5 recorded

19.0

*The averages for air observation do not include the results obtained by aircraft who were only witnessing practices.

DIRECT SPOTTING RULES
(C.B. 3001/37, page 34, paragraph 29.)

15. As a result of trials during 1937 The Commander-in-Chief, Home Fleet, recommends that the further step of ladders should be fired first, and the V.A.C., Battle Cruiser Squadron and R.A. 1st Battle Squadron, agree with this view.

16. Some trials have been carried out in the Mediterranean, using a form of trending, and the recommendation from these is that, after a ladder, the next double should be spread either side of the corrected range. Subsequent spreading to depend on the circumstances at the time, and to be left to the discretion of the control officer.

17. These views are considered sound, and it is desired that the following modifications to the normal rules should be adopted for trial during the year:-

(i) All ladders to be fired with the further step first.

(ii) The next double salvo to be spread 100 yards either side of the corrected range, and subsequently the control officer should use his discretion whether "spreading" should be continued or not.

- Page 31 -

AIRCRAFT SPOTTING

Accuracy of Air Reports of Fall of Shot for Range

18. A collective analysis of aircraft fall of shot reports in "Capital Ship Firings" is shown in the following table:-

Signalled Report

No. of Observations

Percentage of observations with Errors less than 100 yards.

1937 Mean Errors

1936 Mean Errors

KK

100

200

300

400

500

600

700

800

900

1,000 or over

135

138

108

116

80

49

34

23

5

-

2

Per cent.

94

80

73

66

44

24

23

0

0

-

50

Yards

52

56

69

92

108

147

202

261

287

-

325

Yards

67

81

116

121

177

339

299

319

233

212

292

A considerable proportion of these observations was recorded by acting observers and observer's mates, who witnessed the firings. The potential value of accurate aircraft spotting is well illustrated in a gunnery practice by H.M.S. Hood, details of which are given in Appendix VII.

Aircraft Inclination Reports

19. In 14 observations, the mean error of aircraft reports of the target's course in "Capital Ship Firings" was 3.4°, compared with 9.7° in 1936. All reports were made in battle practice target firings, and those made by witnessing aircraft are included.

Aircraft Spotting Rules

20. Both fleets report that the rules given in C.B. 3001/37, page 107 et seq., have proved satisfactory and that no major modifications should be made.

21. The following recommendations in some of the detail have been made, (C.B. 3001/37, Appendix 1)

(a)   Commander-in-Chief, Home Fleet.

If the initial air report is "FAR SHORT" or "FAR OVER," implying M.P.I. more than 1,000 yards from the target, correct towards the target by 2,000 yards, and fire the "A" salvo. Apply a reverse correction of 1,000 yards and fire "B" salvo.

This is concurred in and Rule 4 for finding the range should be amended accordingly.

- Page 32 -

(b)   Rodney

Paragraph 7 on page 107 appears to give contrary instructions to those implied by paragraphs 5 and 6. This is considered a fair criticism and paragraph 7 should be amended to read:-

"7. The shorter the intervals between doubles, the more easily is the target held. The 'A' salvo must, therefore, be fired as soon as possible after the receipt of the report of the previous 'A,' unless for the reasons given in paragraph 5, this report leaves the situation in doubt, and it is desirable to await the 'B' report to avoid wasting a salvo."

(c)    Commander-in-Chief, Mediterranean, and Vice-Admiral Commanding, 1st Battle Squadron

(i) While Rule 10 permitting the control officer to modify the correction to the "B" salvo should be retained, it is not easy to apply as "spreading on the bracket" (paragraph 9) and experience indicates that the latter may be the better method of holding the target.

They recommend that "Spreading on the bracket" should be used for hitting and holding the target at the commencement of the firing. This is concurred in for trial.

(ii) Following on this proposal, and taking account of the accuracy of air reports of salvos with M.P.I. 100 yards from the target, the recommend spreading 100 yards instead of 200 yards either side of reports SSI and GGI. This appears sound and should be tried, but rule 4 will not be amended without further experience.

22. These recommendations cover the question asked in C.B. 3001/37, page 33, paragraph 25.

Collective analysis. (C.B. 3001/37, page 32, paragraph 24.)

23. From the limited number of records, it is not possible to draw conclusions from this form of analysis, but it tends to support rules 6 and 8 doubling the air report, and rule 10, modifying the correction to the "B" salvo, with "spreading on the bracket" a useful alternative.

Owing to its limitations this form of analysis is to discontinued. All the information required can best be obtained from the tables of errors of observation, and the ordinary analyses of practices.

- Page 33 -

SIMULTANEOUS ENGAGEMENTS BY MAIN AND
SECONDARY ARMAMENTS

24. With reference to C.B. 3001/35, page 30, paragraph 46, it is now considered that there is a definite requirement for the main and secondary armaments to co-operate effectively against the same target in certain conditions.

With increased ranges of secondary armaments the scope for co-operation widens, and communications for the interchange of information are being fitted in new construction of capital ships and in existing ships when re-armed.

Warspite has already been fitted with counterdrum receivers to provide the 6-in T.S. with the true range and enemy settings in use in the 15-in T.S. With the 6-in gun range already available in the 15-in T.S., these should meet requirements, accepting some error in deflection and range correction when co-operating on a common gun range.

The Commander-in-Chief, Mediterranean has been requested to arrange trials in Warspite, and to report on the sufficiency of these communications.

- Page 34 -

SECONDARY ARMAMENTS

25. The following table shows the results obtained in secondary armament practices of which reports have been received during 1937. The figure in brackets indicate the results obtained in 1936.

Day

Target and Number of Practices

Mean Range

Full Gun Salvos Per Minute

Output Per cent

Spread

Hits Per gun Per minute

6-in, XXII

145-ft. B.P.T. - 7

H.S. B.P.T. - 6

Centurion - 2

Throw-off - 8

6-in, XII

145-ft. B.P.T. - 12

H.S. B.P.T. - 7

Throw-off - 2

5.5-in

H.S. B.P.T. - 4

4-in

H.S. B.P.T. - 3

Throw-off - 2

15,300

(6,600)

10,800

(12,300)

11,400

_

11,300

(10,500)

8,500

(9,450)

9,100

(7,300)

7,700

(8,000)

12,100

(8,100)

6,500

(7,100)

7,700

(7,700)

3.08

(3.38)

3.19

(3.41)

3.74

(3.93)

3.12

4.11

3.90

(4.51)

4.39

(4.39)

3.23

(4.63)

3.73

(4.47)

5.11

(5.90)

5.53

(5.88)

91.1

(85)

92.9

(97)

93.6

(90.5)

_

92.74

(90.30)

97.11

(92.0)

_

_

87.99

(86.8)

93.92

(100)

-

-

278

(301)

300

(244)

316

(265)

-

194

(267)

241

(191)

_

_

210

(274)

268

(217)

-

-

0.014

(0.468

0.113

(0.175

0.148

(0.100)

0.039

0.147

(0.295)

0.129

(1.102)

0.051

(0.129)

0.129

(0.328)

0.171

(0.164)

0.250

0.051

Night

6-in., XXII

145-ft. B.P.T. - 9

Centurion - 1

6-in., XII

145-ft. B.P.T. - 4

5.5-in.

145-ft. B.P.T. - 2

4-in.,

145-ft. B.P.T. - 2

3,900

(3,100)

5,400

3,100

(3,900)

3,000

(3,050)

5,700

(4,700)

3.15

(2.87)

3.61

2.99

(4.51)

2.40

(3.91)

5.43

(4.77)

96.4

(91)

100

90.57

(96.9)

80

(82.5)

96.2

(94.7)

362

-

130

200

-

250

-

205

-

0.330

(0.202)

(0.620)

0.403

(0.455)

0.000

(0.750)

0.18

(0.00)

- Page 35 -

26. Rangefinding

Armament

Error

Average Error Of 1st Salvo

Per-Centage of 1st salvos to Straddle

Mean Range

At Open Fire

At Cease Fire

6-in., XXII

6-in., XII

5.5-in

4-in

475

226

208

330

227

370

146

250

523

640

577

456

901

901

0

0

124

086

121

069

27. Inclinating

Armament

Average Error In Inclination used

6-in., XXII

6-in., XII

5.5-in

4-in

18°

12°

14°

9.6°

Spotting Rules at Long Range. (C.B. 3001/37, page 25, paragraph 31.)

28. Nelson and Rodney have found the use of triple broadsides instead of rapid at ranges above 12,000 satisfactory, but while this procedure should continue for trial it is not yet desired to standardise it.

It is possible that better results may be obtained by some other procedure, such as rapid broadsides, while hitting, and reverting to triple broadsides with controlled fire for regaining.

SUMMARY OF QUESTIONS ON WHICH FURTHER INFORMATION
IS REQUIRED WHEN OBTAINABLE FROM NORMAL PRACTICES
DURING 1938

B.1. - The suitability of the rule to use a 2,000 yard step, followed by a reverse correction of 1,000 yards on an aircraft report GGF or SSF (paragraph 21(a)).

B.2. - Whether spreading the double salvo 100 yards either side of the best range, or modifying the correction to the "B" salvo, is the better method of holding the target (paragraph 21(c)).

B.3. - Is it sound to spread the double salvo immediately following a ladder, and should spreading continue with either aircraft or direct spotting? (paragraphs 16 and 21 (c) (i))

- Page 36 -

B.4. - Whether spreading 100 yards, instead of 200, on either side of reports SSI and GGI is satisfactory (paragraph and 21 (c) (ii))

B.5. - The relative advantages of triple broadsides and rapid broadsides for secondary armament at long range (paragraph 28).

Pages 36 through 147 are awaiting transcription and thus are currently not included here.

- Page 148 -

APPENDIX VII
GUNNERY PRACTICE BY H.M.S. "HOOD,"
BATTLE CRUISER SQUADRON

15-IN. FULL-CALIBRE FIRING-S.S. H.S.B.P.T.
30.6.37

(See also diagram.)

Object of the practice
1. To exercise the main armament in a high speed full charge firing using aircraft spotting.

Tactical Situation
2. The Battle Cruiser Squadron has accelerated to 27 knots to gain position in the van. Hood will be ordered to open fire at extreme range on enemy battlefleet outside Repulse's range, Repulse will be ordered to open fire on enemy cruiser.

Enemy in sight
3. At this signal armaments are to be trained on targets (Hood, B.P.T., Repulse, H.S.B.P.T.) and loading started. Fire is to be opened as soon as possible after "Flag 5" is hoisted.

Ammunition allowance
4. Hood, four rounds per gun full charge. Repulse, eight rounds per gun reduced charge. No ammunition is to be outside shell rooms or magazines until order "Enemy in sight."

Firing is to be stopped after the salvo which would have expended ammunition had a clean shoot been obtained.

5. After salvo 4, Hood is to assume that her target has been completely obscured by a smoke screen. A competent officer is to be stationed in the director to ensure that the towing ship is not endangered.

6. Owing to weather conditions and the high speed battle practice target towed by Protector only being available, the orders were amended; Hood carried out the practice at this target on opposite courses, and indirect fire was abandoned.

I-NARRATIVE OF H.M.S. "HOOD"

Conditions for the practice

7. Visibility was good, but the horizon to the south-westward was hazy.

8. Although rangefinders had been trained on the target for approximately 3 minutes before opening fire, no ranges were obtained, due to vibration and spray.

9. A wind of 60 miles per hour blowing through the foretop, together with excessive vibration, made conditions for the control exceedingly difficult.

- Page 149 -

Narrative of Events

10. In accordance with the orders for the practice, cages were not loaded. The order to load was given when the report "Enemy battleship reported on the starboard quarter" was received in the foretop.

11. At this time the armament was trained on a look-out bearing of Red 75, and own ship altered course 180° to starboard, the armament being kept trained on the look-out bearing.

12. Armament was reported loaded 1 minute and 25 seconds after the order to load.

13. The order to open fire was received at XV.59.58. No rangefinder ranges had been received (para. 8). The first double (salvos A.1 and B.1) was fired with an estimated range of 20,000 yards, spread 4 knots on either side of the calculated deflection.

14. Salvo A.1 was spotted by the control officer as far right. This was not seen by the spotting officer.
Salvo B.1 was unobserved.
Aircraft reports of G.G. 12 were received for both these salvos.

15. Control officer ordered "Left 12, down 1,400-shoot," "Left 4, up 400-shoot" for salvos A.2 and B.2, respectively.
Control officer subsequently ordered "Down 400," in order to return to the "A" range.

16. After the second double had been fired, the control officer ordered the director and T.S. not to resort to indirect fire. The transmitting station, however, had already made the signal "G.L.N." (target obscured) to the spotting aircraft.

17. Both salvos A.2 and B.2 were unobserved by the control and spotting officers. The rate officer considered the shots to have fallen in line. Aircraft reports of L.F.6 and G.G.1K L.F.7 were received for salvos A.2 and B.2, respectively.
A report of G.G.2 for A.2 was not received, owing to the signal "G.L.N." being made from the transmitting station at the same time.

18. The control officer assumed that the signal G.G.1K referred to A.2, and ordered "Right 4, no correction-shoot; down 200-shoot," before firing A.3 and B.3, subsequently ordering "Up 200," in order to return to the "A" range.
Salvos A.3 and B.3 were unobserved.
Aircraft reports of S.S.2 L.F.6 and S.S.2 L.F.6 were received.

19. The control officer considered the aircraft to be over-estimating the reports for line, and ordered, "Right 4, up 400-shoot, down 200-shoot" before firing salvos A.4 and B.4. It was considered that range had been lost, and the control officer ordered "Rate wants opening." The eighth and last salvo, however, had been fired.

20. Protector reported that the eighth salvo had straddled her.

Mistakes and Delays

Control

21. No istakes were made in obeying the spotting rules, but there were abnormal control delays due to-

(a) The extreme difficulty in spotting; and
(b) Ensuring that indirect fire was not resorted to after the second double that had been fired.

- Page 150 -

Guns

22. Left of "A."-The order "Load, load, load" was given when the armament was on a look-out bearing of Red 75°. Ship was steaming 27 knots while altering course 180° to starboard, resulting in a heel to port, i.e., a heel along the line of the guns.

While the main cage was being raised to the working chamber, the projectile moved forward, passing the surging stop. This caused the projectile to lie slightly diagonally in the cage.

No. 5 in the working chamber did not notice that the projectile was not square in the main cage.

On traversing the carrier back to the waiting position, the nose of the projectile fouled the telecopic rammer head pocket. This caused the projectile to ride over the front dog, straining and distorting the shaft carrying the dogs.

The projectile was levered back into it's normal position and rammed into the gun loading cage.

Due to the distortion of the shaft, the lever operating the dogs would not ride up the inclined cam, with the result that it was impossible to traverse the carrier fully into the hoist to withdraw the second projectile.

The main cage was out of action, necessitating repair by dockyard.

23. Right of "X."-On arrival of the main cordite cage at the working chamber, cordite was seen to be broken up and dropping out.

Examination of material before and after firing showed all gear functioning correctly.

It is considered that, due to the list of the ship when the order to load was passed to the handing room, one quarter charge was not tilted square into the main cage, due to the friction of the base of the charge against the hopper.

The handing room hopper doors were tilted back satisfactorily, and the sashpots were released. But it is considered that this charge jammed the flash-proof rotating buckets of the main cage, preventing them from rotating fully.

The charge probably fouled on the way ip, and as the main cage passed the shell waiting position, the cordite tilted out and was trapped between the cage and the waiting position.

The trunk was drenched and the officer of quarters ordered cordite to be passed up the secondary hoist. One round only was fired. Due to the presence of cordite in the trunk, the main cage was put out of action.

Summary of Salvos, Spread and Rate of Fire

Total Time Salvos
fired
Rounds
fired
Equiv.
F.G. Salvos
per minute
Output,
per cent
Spread Hits/gun/min.
4 min. 15 sec. 8 26 1.34 81.25 135
(1 salvo)
0

- Page 151 -

Analysis of Aircraft Reports

No. of
Salvo
Spread
of
Salvo
Time Lag
from
Splash
No. of
Guns in
Salvo
True M.P.I. Spotting Aircraft Report as Signalled
Range Line Range Error on Correct Report Line Error on Correct Report
1
2
3
4
5
6
7
8

135
Not known
" "
" "
" "
" "
" "
" "

7 s.
8 s.
9 s.
10 s.
12 s.
11 s.
10 s.
9 s.
4
2
4
3
4
2
4
3

+ 900
+ 790

Not known



Not known

G.G.12
G.G.12
G.G. 2
G.G.1K
S.S.2
S.S.2
S.S.2
S.S.2
300
400
-
-
-
-
-
-
-
-
L.F.6
L.F.7
L.F.6
L.F.6
L.F.9
L.F.8


-
-
-
-
-
-
-

Observer's Report
26. The target was slightly into the sun, but there was no cloud and no difficulties were experienced.

II. -REMARKS OF VICE-ADMIRAL COMMANDING, BATTLE CRUISER SQUADRON

27. The reason for shots being out of line has already been dealt with in another place.

28. Owing to the impossibility of accurate raking, no reliable data can be obtained as to the effectiveness of the spotting rules, etc.

III. -REMARKS OF COMMANDER-IN-CHIEF, MEDITERRANEAN

29. The firing was carried out under extremely difficult conditions, and it is unfortunate that a great deal of the value of the practice was lost due to errors of judgement.

30. It would be of interest to know if an occurrence similar to that which caused the loading delay in "A" turret has been reported in any listing trials or heavy weather findings.

IV. -ADMIRALTY REMARKS

31. It is of special interest that in circumstances when rangefinder ranges were infrequent, the initial estimated range was over a 1,000 yards high, and the fall of shot were unobserved from the firing ship, aircraft reports put the fall of shot on the target for range, and probably would have done for line had the reports been accepted.

32. The principal lesson to be learnt is that if the fall of shot cannot be seen, aircraft spotting must be relied on, or fire checked and a fresh start made.

33. With reference to the Commander-in-Chief's remarks, there is no record of any previous failure similar to that which caused the delay in "A" turret, and it is considered that, in view of the impractibility of re-designing the loading arrangements, such failures as those experienced in "A" and "X" turrets can best be obviated in heavy weather by vigilance and good judgement in drill.

- Page 152 -

To be continued...

END OF TRANSCRIPTION