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Official Records
ADM 1-9421 : Main Characteristics of 1937 Capital Ship Updated 03-Apr-2005 This document is a modern transcription of a portion of Admiralty record ADM 1-9421. We'd like to thank Mr David Chessum of Australia for transcribing this for the H.M.S. Hood Association 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. |
ADM 1 9354
SECRET
COPY 1 (Enclosed with MFO 1125.27)
MAIN CHARACTERISTICS
OF
1937 CAPITAL SHIP.
_______________________
Naval Staff
June 1933
Copy No. 1
Main Characteristics of 1937 Capital Ship. Addendum No. 1
To Naval Staff Memorandum dated June, 1935.
__________
Staff Requirements – Anti-Gas Measures for a Battleship.
__________
Personnel in a battleship are provided with protection against gas in the following degrees:-
- (A) Perfect collective protection by means of filtration units fitted to ventilating system of compartments occupied by personnel engaged in important duties, which prevent personnel wearing respirators.
2. It is recommended that unless technical difficulties outweigh the advantages of providing complete gas protection, “A” should include the following compartments in a battleship:-
- (i) Main armament fire control room.
(ii) Secondary armament fire control room.
(iii) A.A. armament fire control room (H.A.C.P.)
(iv) All telephone exchanges.
(v) Main switchboard.
(vi) Headquarters of Second-in-Command (usually the lower conning tower).
(vii) The strategical and tactical plotting room under armour (Flagship’s only).
3. Constructive and ventilating arrangements should permit of gas citadel being provided for B.
4. In addition, decontamination arrangements are required both for personnel and clothing.
For the former, who will be contaminated most probably when above the upper deck, showers, etc., are required in the super-structure opening out on to the upper deck. For the latter arrangements for decontaminating clothing in bathrooms and in the steam disinfecter are needed.
5. Technical requirements are stated in O.U. 5427 – Defence against Gas (Navy) – these should be examined in detail in conjunction with D.T.M’s Department.
(June 1933)
MAIN CHARACTERSTICS OF 1937 CAPITAL SHIP.
General Remarks
Although there have been few changes of real importance since the deliberations (1928) on the 1931 battleship, it is necessary to comment on certain matters which must be taken into consideration, when putting forward further proposals.
2. The most important foreign developments have been the building of the ships of the DEUTSCHLAND type in Germany; and the laying down of the French DUNKERQUE in reply. The former is an 11” gun ship, with a 4” (or 5”) belt and 2” deck, and 26 knots; the latter a 13” ship, with an 8.8” to 9.2” belt and 4” deck and 30 knots.
These ships are both of the battle cruiser type; the DEUTSCHLAND are ideal “trade” work ships, and the DUNKERQUES appear to be designed with the sole idea of opposing them.
It seems quite probable that Italy will build one or two ships of a similar type to the DUNKERQUE and in reply to that design.
3. In America the battle fleet has been modernised; among other features are, a full speed of 21 knots, a great endurance and heavy protection. In regard to the latter feature, in spite of a saving of 800 tons by the installation of modern machinery, there is an increase in displacement of 3,000 tons, expended chiefly in “blisters torpedo bulkheads and A.W. protection.”
4. In Japan the battleships and battle cruisers have been “modernised” (1926 and onwards); “in order to increase the defensive power against submarine and aerial attack, the decks have been strengthened, involving an increase of about 3,000 tons displacement.”
5. In regard to Speed; Japan will have 3 battlecruisers of 26 knots, France possibly 2 of 30 knots, and Germany 4 of 26.
It may be noted that the Japanese ships are older than any of their battleships, and presumably first due for replacement.
Battlefleet speeds are as follows – U.S.A. 21 knots, Japan 23.
6. As regards Main Armaments; U.S.A. has 3 and Japan 2, 16” ships; the remainder of the American and Japanese ships are armed with the 14” gun. The 13” guns of the new French battle cruisers and the 11” of the German DEUTSCHLANDS have already been mentioned. The Italian battleships have 12” guns.
7. In the British fleet, the BARHAM has been given additional deck protection over the magazines and the REPULSE is also being improved in tis respect. It has not been found possible to deal with our remaining battleships; their vitals are penetrable by 1,000 lb. A.P. bombs and the rest of their decks by 50 lbs. from comparatively low altitudes.
8. Fighting Methods.
Guns.
The most noticeable feature has been the development of long range fire in the American Navy.
Air.
There can be little doubt that the next 20 or 30 years will see considerable development in this form of attack. In America the form of attack most in favour at present is “Diving Bombing”, with 1,000 lb. bombs, due no doubt to the large percentage of hits obtainable and the difficult target presented. “High bombing,” with bombs up to a maximum of 2,000 lbs. remains a distinct possibility, though the number of cloudy days and the small percentage of hits detracts from its value. The “T/E attack” is not much favoured in any other country than Great Britain, partly, no doubt, because the underwater protection to meet the more powerful torpedo of the surface ship is more than able to deal with that carried by the aircraft (see also “Underwater attack”), and partly because of the easier target offered to close range A.A. guns. (“B” bomb and “Near-Miss” under the “Underwater Attack.”).
Underwater Attack.
The “1,000 lb. head” for torpedoes has not been adopted in this country, and, so far as is known, there is no suggestion of it elsewhere. We know that a 1,000 lb. head can be carried, but this is not al all likely in Destroyers or Submarines owing to difficulties of handling and space; it is impossible in aircraft; if carried at all it must be in battleships and cruisers.
Attack on the (at present) unprotected portion of the ship’s bottom is a practical certainty of the near future; the “B” bomb has already gone far enough to justify the assumption that it will be in general use during the life of any ship that we may build.
Under this heading also is the “Contact-Non-Contact” pistol for torpedoes; progress in connection with which justifies us in assuming it as a probability of the comparatively near future.
This will make the T/B attack a serious menace again, and will increase the potency of the present torpedo.
A further problem I this connection is the “Near-Miss” with large bombs; this has been investigated in America (1921), and the OSTFRIESLAND was finally sunk in this way. It is understood, however, that owing to the difficulty of “near-missing” they now prefer to hit the ship itself.
Chemical Warfare.
There have been no new developments in this direction, and it is not a form of attack which appears to be favoured in foreign Navies, with the possible exception of the U.S.S.R.
9. The life of the 1937 battleship will probably cover a transition period, curing which the results of disarmament conferences will be taking effect.
It will be necessary to watch the trend of foreign construction very closely, and not to commit ourselves to the perpetuation of a whole class, until we are satisfied that each unit is adequate in comparison with foreign powers.
It is considered that the ship, being a battleship, should meet the requirements of the type as closely as possible, whatever her displacement. Clearly, if there is to be considerable reduction, it will not be possible to meet these requirements in full until the larger ships have disappeared; in the meanwhile there are certain directions in which there is a limit below which we cannot afford to go.
Displacement and calibre of main armament may be fixed for us; the two chief factors remaining are, speed and protection. In these respects it is considered sound policy to give the ship a normal battleship speed which she is likely to retain in action; it is, in fact, preferable to have a moderate speed, but well protected, than to strain for a high speed which not only cannot be adequately protected, but which may be difficult to retain towards the end of her life.
(I), (II) and (III).
GUNNERY CHARACTERISTICS OF THE NEW CAPITAL SHIP.
Recommendations for the various armaments of the new battleship, in so far as they concern D.T.S.D, are submitted herewith.
In preparing this memorandum, the requirements laid down in 1928 have been carefully examined and when applicable the Naval Anti-Aircraft Committee’s Report has been consulted.
The only points dealt with in any detail are those in which recommendations as to armament are divergent from the conclusions of the 1928 requirements.
These points are –
(i) Disposition of Secondary Armament.
The conclusion arrived at in this paper is that for L.A. purposes it is preferable to mount the guns on battery mountings and that the elevation above 30º possibly required for A.A. purposes, should be sacrificed.
(ii) The number and calibre of guns required for the Main A.A. Armament.
As a result of the N.A.A.C.C. recommendations, it is proposed that 6 guns each side should be mounted instead of 4, and in view of the higher rates of fire recently achieved with 4-inch hand-worked buns, it is recommended that a decision on the calibre of the gun to be mounted should be deferred.
The requirements for the various armaments have been dealt with under the following headings –
- 1. Disposition of the Main Gun Armament
______________
Amendment to Naval Staff Memorandum dated June 1933.
MAIN CHARACTERISTICS OF 1937 CAPITAL SHIP.
GUNNERY CHARACTERISTICS I.
DISPOSITION OF THE MAIN GUN ARMAMENT.
In 1928, after a great deal of detailed discussion, the conclusion was that the Main Armament of the 1931 Battleships should be mounted in twin turrets, the number of turrets to be not less than four; the turrets to be placed as in the Queen Elizabeth Class.
2. This method of disposing the Main Armament is still strongly advocated.
3. If, for reasons connected with adequate protection and limited tonnage, it is found impossible to mount the armament as above, then the method of mounting the armament in three triple turrets disposed as in NELSON class, could be accepted, provided that :-
- (a) The loading cycle of each gun of the triple will not be appreciable greater than that of a similar gun mounted in a twin turret.
Note:- The above supersedes the fifth page of the Naval Staff Memorandum, dated June 1933. The Superseded page is to be destroyed.
23 Nov 1933.
- 2. CALIBRE AND DISPOSITION OF THE SECONDARY ARMAMENT.
1. The following is a summary of the requirements laid down in 1928 -
The secondary armament to consist of 12-5 inch guns, mounted 6 each side.
To be capable of 60º elevation.
Rate of fire to be 8 rounds per gun per minute.
Flashtight arrangements to be provided.
Protection to be provided against weather, blast of own guns and enemy shel or bombs, and against fragments except the heaviest.
2. The conclusion reached in 1928 was that these requirements could only be met by mounting the guns in pair turrets.
Limits of Elevation for the L.A. Secondary Armament.
3. In C.0508/33, D.N.O. states that “It is not considered impossibl to mount 6” guns in batteries with 30º of elevation.”
4. So long as the requirement for elevation exceeds 30º, the mounting of the Secondary Armament in turrets will have to be continued: the other requirements can, however, be met by arranging the guns either in batteries or groups.
5. Since the advent of the 8 inch cruiser, the policy has been to give all 8 inch and 6 inch mountings such an elevation as will allow of aircraft being engaged at long and medium range.
6. The difficulties of providing H.A. control systems and arranging for an adequate supply of H.A ammunition have, however, not been overcome at the present time.
7. If the guns in ships of new construction can be given this extra elevation without adversely affecting the general design of the ship, we are on the safe side in providing it and relying on some form of control being provided at a later date.
8. If, on the other hand, there is a definite material advantage to be gained by limiting the elevation of the Secondary Armament to meet L.A. requirements, then the possible requirement for using these guns against aircraft at logn range should be regarded as of lesser importance.
Conclusion.
9. When the secondary armament is separate to the H.A. armament, the limits of elevation for the guns should be governed mainly by the L.A. requirements.
Comparison between battery and turret mountings for the L.A. Secondary Armament.
10. The advantages and disadvantages of batteries as compared with turrets are considered to be -
(i) Broadside Batteries.
Advantages.
- (a) More reliable due to absence of machinery and probable effect of splinters.
- (b) Crews fairly well protected.
Disadvantages.
- (a) Arcs of fire not as good as turrets.
NOTE: - (i) Judging from results of LEANDER’S gun trials, rate of fire for short periods should be approximately the same with both turret and battery mountings.
- (ii) In G.0508/33, D.N.O. indicates that there would be no saving in personnel
in the turret method when supply parties are taken into account.
11. In G.0508/33, D.N.O. draws attention to the fact in the 1928 recommendations “insufficient stress is laid on reliability, in which important matter the broadside battery is superior both in respect of absence of machinery and probably effect of splinters.” This statement is fully concurred in, and whilst appreciating that the advantages and disadvantages tabulated above are very similar to these that were considered in the framing of the 928 requirements, the conclusion now drawn is that the battery mounting is preferred to the turret in spite of the possible disadvantages in respect of arcs of fire, ammunition supply and weather.
Disposition of the Secondary Battery.
12. The three disadvantages, referred to in the previous paragraph, can be partly if not entirely overcome by mounting the guns in some form of grouping on a higher level than the present battery guns in the QUEEN ELIZABETH and ROYAL SOVEREIGN Classes.
13. It is therefore recommended that the Secondary Armament should be mounted in groups on as high a level as possible.
14. Summary of Conclusions re Secondary Armament.
(1) To consist of 12-6 inch guns mounted in battery mountings.
(2) To have improved arcs of fire, ammunition supply arrangements and weather tightness as compared with QUEEN ELIZABETH and ROYAL SOVEREIGN Classes. This suggests some form of grouping and on a higher level.
(3) To be capable of (approximately) 30º elevation.
(4) Rate of supply to be 8 rounds per minute.
(5) Flashtight arrangements to be provided.
(6) Protection to be provided against blast of own guns and enemy shell or bombs, and against fragments except the heaviest.
_____________________
- 3. CALIBRE, DISPOSITION AND NUMBER.
A.A. ARMAMENT.
The requirements laid down in the 1928 recommendations were that the A.A> armament of the future battleship should be –
2. 8-4.7” H.A. guns mounted in twin between deck mountings, four guns each side. Largest possible arcs of training to be provided and elevation up to 90º. The rate of fire to be as high as possible and not less than 8 rounds per gun per minute. The guns’ crews to be provided with full protection against weather, blast of own guns, and as good protection as possible against blast and fragments of enemy shell or bombs.
3. Since these requirements were stated, the N.A.A.G.C. have rendered their report and in it they have dealt exhaustively with the whole question of A.A. defence.
4. They discuss in Chapter I; III – 32 and 33 the policy as to number and calibre of H.A. guns, adopted by Foreign Navies as follows -
“As far as our information goes, Japanese, French and Italian battleships still have from four to six 3-inch A.A. guns, but the acceptance of a policy demanding more and heavier guns is reflected in the A.A. armaments of new cruisers of these Nations (vide table below), so that a re-armament in A.A. guns in battleships may reasonably be expected.
In United States battleships a definite step forward has already been made. All ships earlier than MARYLAND originally had eight 3-inch A.A. guns. In recent years, however, over £3,000,000 has been spent on re-arming with 5-inch A.A. guns and fitting new fire control, and all United States battleships now have eight 5-inch A.A. guns (except the four oldest ships and even for these money has been voted).”
Table of Main A.A. Armament of Foreign Cruisers.
|
Ships. |
Main Armament. |
Main A.A. Armament. |
|
|
United States |
|||
|
NEW ORLEANS. |
7 |
9-8 inch. |
8-5 inch H.A. |
|
Japan |
|||
|
NACHI |
4 |
10-8 inch. |
6-4.7 inch H.A. |
|
Italy |
|||
|
TRENTO and ZARA |
7 |
8-8 inch. |
16-3.9 inch H.A. |
|
France. |
|||
|
COLBERT and FOCH. |
4 |
8-8 inch. |
8-3.5 inch H.A. |
|
ALGERIE |
1 |
8-8 inch. |
12-3.9 inch H.A. |
NOTE - Older foreign cruisers are mostly armed with 3-inch H.A. guns.
5. In Chapters 3 and 4, the N.A.A.G.C. discuss the most suitable number and calibre of guns and type of mounting for A.A. work, and their recommendations in Chapter 3 for the A.A. armament of a future capital ship are as follows -
(a) If displacement and other considerations allow -
6-5.1 inch guns each side on B.D. mountings.
- (b) Minimum armament –
4-5.1 inch guns a side.
(c) If it is impracticable to mount the 5.1 inch gun -
6-4.7 inch guns each side on B.D. mountings.
A maximum of elevation for (a), (b) and (c) to be 70º.
6. The Committee’s recommendations as to the number of guns, method of mounting and maximum elevation are concurred in but the question of the most suitable calibre of gun is further discussed below.
Calibre of Gun.
7. A point strongly stressed in the Committee’s report was that in their opinion a great advantage lay with the heavier calibre.
8. The Committee’s conclusions were that, assuming equal rates of fire for the different calibres -
One 5.1 inch gun was equivalent to three 4 inch.
One 4.7 inch gun was equivalent to two 4 inch.
9. Recent Fleet practices have shown that the Committee’s adoption of equal rates of fire is an incorrect assumption, since at elevations less than 40º (about), the 4-inch gun is capable of double the rate of fire of the other two. The assumption is, however, probably approximately correct for any calibre of power-worked A.A. guns of 4-inch calibre and above, and for the hand-worked 4-inch gun at elevations greater than about 40º.
10. It may be that by increasing the 4-inch rate of fire to its maximum, one four inch hand-worked gun will be proved equal to one 4.7” power-worked gun – sufficient data to give a decision on this point is not available at the present time since neither a power-worked 4.7 inch twin mounting nor a hand-worked 4-inch twin are yet in existence, and their respective capabilities and reliability are not, therefore, known. It must also be noted that the firing of the hand-worked 4-inch H.A. gun at high rates of fire has been carried out only under ideal conditions of elevation and weather; its full capabilities under all conditions are not yet, therefore, definitely established.
11. Conclusion as to Calibre of Gun.
As the 5.1” gun and mounting has not been developed for A.A. purposes, it cannot be considered as a possible weapon for the new capital ship.
At the present time we are not in a position to give a definite opinion as to whether the 4.7” or 4” gun should be mounted.
It is therefore recommended that the new battleships should be designed so as to permit of 4.7 inch twin mountings being fitted. If it is decided later that 4-inch hand-worked twin mountings would be preferable, there should then be no difficulty in installing them.
12. Summary of Conclusions re Main A.A. Armament.
(i) 6 guns each side or alternatively two twin mountings each side with one on the centre line.
(ii) The guns to be mounted in between deck twins to provide the guns’ crews with full protection against weather, blast of own guns, and as good protection as possible against blast and fragments of enemy shell or bombs.
(iii) The design of the ship to be such that either the 4.7 inch or 4 inch gun can be mounted. A decision to be given later as to which calibre is preferable.
- (iv) Largest possible arcs of training to be provided and elevation up to 70º.
______________________________
5. COMBINATION OF L.A. AND H.A. ARMAMENT.
1. The advantages and disadvantages of combining H.A. and Secondary armaments have been fully discussed by the N.A.A.G.C. since the 1928 Requirements were drawn up.
The Committee’s conclusions were -
- (a) That the ideal is to have separate L.A. and H.A. armaments.
2. In 1931 the late Controller stated in S.O.36449/31 -
“I consider there may be great advantages in a combined H.A. and L.A. armament of about 5 inch calibre as it is difficult to mount large numbers of different calibre guns in positions which are in all respects advantageous.”
3. Whilst fully concurring in these opinions, it is desired to emphasise that the only gun available at the present time for mounting for the dual purpose is the 4.7 inch. This gun does not possess the necessary stopping power for use against modern destroyers, and its range of splash visibility is limited to 14,000 yards. These two important factors would seriously affect L.A. efficiency.
4. Conclusion.
A combination of the L.A. H.A. armament of a smaller calibre than 5.1 inch is not recommended as it would entail too great a sacrifice of L.A. efficiency.
_____________________
4. POSSIBLE USE OF L.A. SECONDARY ARMAMENT FOR A.A. PURPOSES.
1. A secondary armament of 6-inch calibre with 30º elevation would be capable of engaging aircraft under the following conditions -
(a) 10,000 feet between 6,500 and 18,000 yards.
(b) 6,000 feet between 3,800 and 20,000 yards
2. Whilst admitting that this might be a valuable addition to the A.A. defence, no recommendation is put forward for superimposing an H.A.C.S. on these L.A. weapons owing to the difficulty of providing a control system both simple and efficient. The N.A.A.G.C. views on the subject are given in Chapter II, II-20, and are as follows -
“The trials of system H.X. for control of secondary L.A. guns against aircraft at long range demonstrated that the problem cannot be effectively solved with rough and ready fire control material. Further, unless a complete system of H.A. control such as the H.A.C.S.I. is fitted, the training required to obtain efficiency is very considerable.”
(Note - The system H.X. for control of secondary L.A. guns was fitted and tried in HOOD in 1928 and in RENOWN, REPULSE and CURACOA in 1929).
3. The Committee’s recommendations for future ships are given in Chapter 13; I – 2:-
“To augment A.A. defence, a minimum of six 6-inch guns each side with a total of four combined H.A./L.A. control positions are recommended. The 6-inch guns to be adapted for supplementary use against aircraft at long range, as proposed for NELSON and RODNEY.
(Note - The control proposed for NELSON and RODNEY was H.A.C.S.I. B.)
4. The policy now accepted for all battleships (except possibly NELSON and RODNEY, who have 60º 6-inch mountings) is that the secondary armament is not to be employed for long range A.A. purposes.
5. Owing to the expense and complication involved in giving the secondary armament a really efficient H.A.C.S. at present, it is recommended that this policy should also be adopted for the new battleships.
6. If and when an efficient form of control less elaborate than H.A.C.S.I. B. has been evolved, the question of its adoption for these weapons could be considered.
7. Conclusion.
Provided an adequate H.A. armament is mounted, no attempt should be made to include the L.A. armament for long range A.A. fire beyond the provision of 30º elevation to meet possible future developments in H.A. control.
____________________
9. Number and Type of Aircraft.
6 T.S.R. aircraft amidships; 2 catapults and 2 cranes.
10. Bridges.
Bullet proof protection; protection from wind and weather.
High and clear hoist for flags, clear arcs for S.P.; semaphores etc., clear view from signal deck.
Night fighting arrangements as in NELSON.
11. Number and Disposition of Searchlights.
2 below forebridge (or thereabouts).
4 aft in funnel positions.
12. Conning Tower.
None required.
Control Positions.
Main. (1 forward, high up.
(1 aft, low down.
Secondary. (1 forward starboard.
(1 forward port.
A.A. (1 forward.
(1 aft.
Mark “M’ Pom-Poms. 1 for each fitted.
__________________
- 6. CALIBRE, DISPOSITION AND NUMBERS OF
THE CLOSE RANGE ANTI-AIRCRAFT ARMAMENT.
1. The N.A.A.G.C. in Chapter 13 of their report state -
“It is considered that capital ships should carry four Mark M Pom-Poms (director controlled) and eight 0.5 inch multiple machine guns fitted so that they are clear f gun blast and so that as far as possible two pom-poms and four machine guns can fire on any one bearing at the same time.”
2. These requirements are concurred in, but it is appreciated that other considerations may necessitate a weaker armament.
_________________
- 7. NUMBER OF CONTROL POSITIONS AND APPROXIMATE
LOCATION FOR EACH TYPE OF ARMAMENT.
It does not appear that this subject was discussed when the 1928 requirements were put forward; the control arrangements of NELSON have, therefore, been taken as the basis from which to work in proposing control arrangements for the new battleships.
A comparison between NELSON’S arrangements and the arrangements proposed for the new battleships is given below.
The proposals for each type of armament are the minimum requirements, in order to reduce as much as possible the amount of control material fitted in these ships.
Unless this policy is adopted, the maintenance of the control material will be such a large consideration that normal training of personnel will suffer, and difficulty will be found in manning all the control positions.
|
NELSON’s Control Positions. (When fitted with second set of H.A.C.S.I and second pom-pom). |
Proposed Control Positions for New Battleships |
|
Main Armament. |
|
|
1 forward and high up. 1 aft and low down. 1 forward on top of the conning tower. |
1 forward and high up. 1 aft and low down. |
|
Secondary Armament. |
|
|
1 forward starboard side. 1 aft starboard side. 1 forward port side. 1 aft port side. |
1 forward starboard side. 1 forward port side. Simple arrangements to be Made for local control of group. |
|
Main A.A. Armament. |
|
|
1 forward. 1 aft. |
1 forward. 1 aft. |
|
Mark “M” Pom-Poms. |
|
|
1 for each gun fitted. Total 2. |
1 for each gun fitted. Maximum 4. |
|
Total – 11 |
Total - 10 |
Possible Combination of Control Positions and Transmitting Stations for the Secondary and Main A.A. armaments in New Battleships.
On a separate paper a scheme has been proposed to D.N.O. to combine the control positions and to combine the Transmitting Stations of these two armaments. If this scheme is practicable, two less control positions and two less transmitting stations would be required.
- (IV) THE TORPEDO ARMAMENT: WHETHER ANY AT ALL IS TO BE FITTED, AND IF SO, ITS DISPOSITION.
When the main characteristics of the design of 1931 battleships were laid down in 1928, the arguments for and against a torpedo armament were set out at some length.
2. The following conclusion was reached:-
“It is therefore considered that it would be unwise to abandon a part of the main offensive armament of capital ships unless an adequate increase can be obtained in the other part, namely the gun armament.”
3. Since that date circumstances have changed and it is considered that the advantages offered today by a torpedo armament are greater than they were five years ago, whilst the disadvantages then put forward have diminished materially. Also it is now considered that there is a serious under-statement in the assessment of damage to be expected to result from a hit with a modern torpedo which was used in the previous arguments on this subject, and which is published in C.B.3011 – “War Game Rules, 1929”. This matter is being taken up on a separate paper, T.D.12/33.
4. The arguments for and against the carriage of torpedoes in capital ships were fully discussed on T.D. 50/33.
5. Since the 1928 discussions, it is considered that the changes in the situation which have taken place all lead to a strengthening of the arguments in favour of the provision of torpedoes.
The principal change, which has already been referred to is the possibility of actions being fought at night in which case the importance of an adequate torpedo armament could not be disregarded.
6. On the assumption that no restriction is involved in the numbers and disposition of the guns of the secondary and H.A. armaments, it is proposed that the following should be the general features of the torpedo armament:-
(a) Torpedoes running on normal air should be provided, every endeavour being made to provide for an increase in speed. The weight of explosive in the head should be limited to 750 lbs., unless future developments point to an increase being necessary.
(b) Tubes to be fitted above water. One quintuple mounting should be installed each side with arrangements for reloading tubes on the engaged side from the other mounting if desired, the warheads will be outboard in action.
(V) ARMOUR PROTECTION.
(a) Against gun attack.
(b) Against air attack by bombs.
____________
1. The protection proposed in 1928 was for a 16” capital ship. The proposals included protection of the magazines against 16” shell between 12,000 and 30,000 yards, and against the 2,000 lb. bomb from 10,000 feet; the main armament to be protected against 16” shell between 12,000 and 26,000 yards; the machinery spaces against 16” plunging fire up to 26,000 yards, the side armour not being penetrable outside 12,000 yards (@70º), against the 2,000 lb. bomb from 4,000 feet and against the 500 lb. bomb from 10,000 feet and below. The steering gear was to be protected against all but direct hits near the normal, and the secondary armament, control positions etc., against splinters, blast of 16” shell burst or 2,000 lb. bomb burst, and from weather.
2. So far as the 16” ship is concerned, the only development which affects the situation is that of “terminal diving” with 1,000 lb. bomb in U.S.A., already carried out and a certainty in the near future. It is therefore considered that the protection given to the machinery spaces should be increased to read “against the 1,000 lb. terminal velocity dive” bomb attack. Remainder as before.
3. For a battleship of less displacement, different proposals are required, and the standard of protection must be reduced as much as is possible while still retaining the essential characteristics of a battleship.
4. In the investigations into a smaller capital ship on S.O.3649/31 the proposals in regard to protection were:- “Belt and barbette armour of a thickness corresponding to the calibre of the main armament; 4” deck against bombs”. This design was for a 30 knot battle cruiser; the protection is insufficient for a battleship, and the tonnage saved on speed (battleship, 23 knots), will be available to bring it up to the standard required.
5. As regards protection against gun attack; there are only 5-16” battleships in the world apart from our own 2, (i.e. 3 U.S.A. and 2 Japanese), and it is not at all probable that we shall be faced with a combination of these 2 powers.
It is, of course, possible that any Treaty may subsequently be abrogated, and larger ships again built; but this is a contingency which cannot be fully guarded against in the design of a smaller ship.
The remaining Japanese and American battleships carry 14” guns, other nations less; and this will, presumably, be the principal gun afloat during the transition period over which the new ship’s life will extend.
It is considered that the standard of protection against gun attack, should be against the 14” gun.
6. The scale of Bomb attack can only be limited by what is practicable, and so far as seaborne aircraft are concerned, this may be taken as the 2,000 lb. bomb.
If an A.P. bomb penetrates into the magazine of a ship she will be blown up; it is therefore a fundamental requirement that protection be provided against penetration by the largest bombs that can be carried in carriers, (i.e., 2,000 lbs).
“Terminal velocity dive” bombing with 1,000 lb. bombs has already been mentioned, and there is little doubt that a high percentage of hits will be obtained by this means, and that it will be difficult to counter by active defence. It will be necessary for the machinery spaces to be protected against this form of attack.
NOTE:- Approximate thickness of N.C. steel penetrated by a 1,000 lb. A.P. bomb has been calculated as follows:-
|
Aircraft speed at end of dive. |
Height of Release. |
|
|
m.p.h.
|
1,200 ft. |
2,000 ft. |
|
320 |
3.43” |
3.86” |
|
400 |
4.20” |
4.5” |
Present performance is reported as 320 m.p.h. with 1,000 lb. bomb, but the higher speed is regarded as probable in the near future.
7. The requirements for protection against gun and bomb (in the case of a capital ship of reduced displacement) may now be stated as follows:-
Magazines. (1) Against penetration by 14” shell between 12,000 and 30,000
yards
(Note:- Penetrable by 16” shell under 14,000 yards).
- (2) Against 2,000 lb. A.P. bomb dropped from 10,000 feet and below.
(Note:- Impenetrable by 16” and smaller shell under 33,000 yards).
Engine and Boiler Rooms.
- (i) Against 14” plunging fire up to 26,000 yards; the side armour not being
penetrable outside 12,000 yards at 70º inclination.
(Note:- Penetrable by 16 shell under 14,000 yards at 70º inclination).
- (ii) Against the 2,000 lb. bomb when dropped from 4,000’ and below.
(Note:- Impenetrable by 16” and smaller shell under 25,000 yards).
- (iii) Against the 1,000 lb. “terminal velocity dive” bomb.
Main Armament.
Ammunition supply arrangements as well as gun house to be protected from 14” shell at ranges between 12,000 and 26,000 yards at 70º inclination.
Same protection against bombs as for Engine and Boiler Rooms.
Secondary Armament, Ship and Armament Control Positions.
To be protected against splinters, blast of 14” shell or 2,000 lbs. bombs bursting in their vicinity, against weather, blast of own guns and machine gun attack by aircraft.
Steering Gear.
To be protected against all but direct hits near the normal.
- (VI) UNDERWATER PROTECTION.
1. The decisions reached as a result of the 1928 discussions, were as follows:-
Anti-torpedo.
To provide against 750 lbs. charge in contact with the ship’s side.
Anti-mine.
To accept 5 feet between bottoms unless D.N.C. could improve on this.
The anti-torpedo protection was to be built in and fitted internally, and would be extended as far forward as possible.
As regards the anti-mine protection, it was stated that t had been found necessary to have a depth of 7 feet between the inner and outer bottoms to give effective protection against eh modern mine. This, in practice, was found impossible to provide on the tonnage allowed, consequently 5 feet had been allowed in the NELSON Class.
2. In the investigations (S.O.3649/31) into a smaller capital ship in 1931, “underwater protection against 750 lb. mine or torpedo was envisaged.
3. As regards anti-torpedo protection, it was stated (1928) that to achieve the 750 lb. protection in NELSON, the maximum limits of beam, compatible with docking facilities and the Panama Canal, were reached.
On the other hand, although the 1,000 lb. offensive has not developed as yet, a charge of this size can be carried in a torpedo; and in view of the progress in torpedo design during recent years it is not unreasonable to expect that this ma be a normal practice during the lifetime of the ship under consideration.
It is considered that progress in under-water protection should aim at providing protection against the 1,000 lb. head without increase in dimension.
4. As regards anti-mine protection; the “B” bomb has been referred to, and its production in the near future is certain.
The charge requirement for this bomb is stated as “sufficient to damage the inner bottom of the NELSON”.
There seems no reason why a much larger bomb of this type should not be developed.
The “contact-non-contact” pistol will also, probably, be in production in the near future and there appears to be no reason why it should not be fitted in the warheads of any torpedoes carried.
5. It is understood that experiments are in progress in regard to anti-mine protection, but it seems evident that it will never be possible to give full protection to the inner bottoms f ships against attacks on the scale visualised in the preceding paragraph. In these circumstances, the only
Policy to adopt would appear to be to provide the best anti-mine protection possible, and it is considered that the original requirement of 7 feet between bottoms should be incorporated. In addition, special attention to be paid to the sub-division of compartments for the localisation of damage and flooding.
6. The “near-miss” by heavy bombs was mentioned in previous discussions. In 1921 the ex-German battleship OSTFRIESLAND was sunk by two-2,000 lbs. in this way. Commenting on this the D.N.C. (Sir T.D’Eyncourt) remarked:-
“It is certain that a vessel where protected by bulges as designed for capital ships is in no danger of sinking. At the ends of the vessel, before and abaft the bulges, the sub-division will localise the entry of water following damage to the outer plating. It is probably that some slight modifications in construction of such parts of a ship may have to be arranged for if the danger of such explosions is to be guarded against.”
7. The underwater protection of a battleship is an “essential characteristic”, for if lower standards are accepted, the ship becomes exposed to extraneous weapons. It is therefore recommended that reduction in total displacement shall not involve a reduction in the standard of this protection.
8. The requirements for underwater protection are, therefore, as follows:-
- (a) Anti-Torpedo.
To provide against a 1,000 lbs. charge in contact with the ship’s side.
To afford the best protection possible, the standard provided in NELSON being regarded as an absolute minimum. Special attention being paid to the subdivision of compartments in this area.
To provide against the effects of a near-miss by 2,000 lb. bomb, outside the area covered by the anti-torpedo protection.
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- (VII) SPEED
1. In 1928 the Staff Memorandum examined this requirement from the viewpoint of the tactical value of a superior battlefleet speed.
The conclusion reached was that “a slight superiority in battlefleet speed on either side is of little account”; whilst, therefore, it would be desirable to attain equality with the designed speed of the fastest foreign vessels, and to maintain the previous British battleship standard, it is considered that a minimum designed speed of 21 knots could be accepted provided that an adequate increase of offensive or defensive power results; the report added “It is important, however, that the machinery should be designed so as to be sure of maintaining the initial speed as far as possible during the life of the ship.”
At the Sea Lords Meeting of 12th October, 1928, the above requirement was discussed, and the two following alternatives were considered:-
“Either design for 21 knots with the purpose of maintaining that speed throughout the life fo the ship, or design for 23 knots, which would be obtained by forcing the boilers, and which would be subject to reduction with age.”
The conclusion reached was “that the best policy was to aim at a speed of 23 knots in standard condition and that a greater forcing of the boilers than has heretofore been accepted should be allowed”.
2. The above requirements and decision in regard to speed were in regard to a 35,000 ton 16” battleship.
On 15th March, 1929, however, a Sea Lord’s meeting investigated the matter of a smaller battleship.
The A.C.N.S. gave the Staff view in regard to speed “The Staff were unable to recommend a policy of increasing speed at the expense of main battleship requirements”; and be later emphasised the value of “balance” in speed from the tactical point of view, and pointed out that “if the battlefleet speed went up, there would be a demand for the speeds of other vessels to rise in proportion.”
This view was opposed, and the D.N.C. was finally instructed to investigate what sacrifice would be necessary if a speed of 23 knots was exceeded.
At this meeting the D.N.C. stated that an increase of speed from 23 to 25 knots would involve an extra 1,000 tons displacement.
3. Little has happened since these investigations took place, to cause the Staff to alter their view that very little advantage is to be expected from a superiority of 2 or 3 knots in battlefleet speed.
The arguments in favour of high speed were based on the supposition that speeds would increase in the future in all classes of ships, and that high speed was essential to deal with the attack by “extraneous weapons”.
Although no capital ships have been built since that date, the position in regard to 8“ cruisers is illuminating; all foreign countries have gradually reduced speed in favour of protection.
As regards “extraneous weapons”, the chief of these is the aircraft, and in this case it has already been clearly shown that attacks are made with ease on a ship moving at 28 knots and with full freedom of manoeuvre; in fact, no possible battleship speed can seriously affect it. The defence against submarines is chiefly by auxiliary craft, and in any case, this threat is not a serious one in battle when full speeds are being used.
On the whole, therefore, there is no good reason to depart from the views previously expressed.
If there is to be a reduction in displacement, all other items will presumably be reduced in standard, and it would obviously be impossible to increase the speed under such conditions without seriously impairing other essential battleship qualities.
The speed of the Japanese fleet is 23 knots, and it is considered that this should be regarded as the maximum requirement for our replacement ships, and that if this speed can be obtained without considerable sacrifice of offensive or defensive power, it should be adopted.
- (VIII) ENDURANCE
It is proposed that the fuel carried should be as follows:-
- (i) Sufficient to steam at 20 hours @ 16 knots with steam for 18 knots.
+ 8 hours @ full speed.
+ 16 hours at 18 knots with steam for full speed.
+ 12 hours @ 16 knots with steam for full speed.
All on the hypothesis of 6 months out of dock.
- (ii) An addition of about 35% to above (E. in C. being consulted on this matter)
to allow for abnormal consumption, due to weather, damage, and
oil left in tanks.
_________
- (IX) NUMBER AND TYPE OF AIRCRAFT TO BE CARRIED.
1. This is the first opportunity that has occurred to include in the design of new ships, proper and adequate facilities for the stowage and operation of aircraft.
2. Available space in existing Capital Ships makes it impossible, without extensive alterations, to accommodate more than one or two aircraft, but it is considered that for several reasons it is most necessary to utilise to the maximum the aircraft carrying capacity of ships other than carriers.
These reasons may be briefly stated as follows:-
- (a) The extreme vulnerability of the carriers which makes it possible that they will not be available when required to launch Striking Forces.
3. It is proposed that space should be allotted in the new battleship for 6 “Torpedo Spotter Reconnaissance” type aircraft and either one or two catapults to launch them. The number of catapults to be provided will depend on whether a single catapult could be re-loaded quickly. This could be done if a lift were provided immediately in rear of the catapult, but if rapid loading facilities cannot be provided, then 2 catapults will be necessary. The aircraft should be housed in a hangar and either 1 or 2 cranes will be required to hoist them in.
4. The “Torpedo Spotter Reconnaissance” type is proposed as being the most suitable type to fulfil all the requirements mentioned in paragraph 2 above in addition to spotting.
5. These proposal entail provision of offensive armament (Torpedoes, Bombs and ‘B’ Bombs) for the aircraft and of suitable workshop and maintenance facilities.
6. The use of towed canvas ramp is envisaged for use when recovering aircraft which would normally operate on floats.
7. Spotting aircraft would continue to be provided as at present, but he ships for which they will spot, and the remaining aircraft would form a powerful Striking Force for use against the enemy’s aircraft carriers or Battlefleet according to circumstances.
8. As it appears probable that the turrets in the new ship will be disposed as in the “QUEEN ELIZABETH class, it is proposed that space should be allocated amidships for 6 “Torpedo Spotter Reconnaissance” aircraft with either one or two catapults and one or two cranes.
It is, however, desired to point out that the most convenient part of the ship from which to operate aircraft is
the stern and had the lay out of the main armament followed the practice adopted in the NELSON class, the whole of the space normally occupied by the quarter deck and immediately beneath it could have been used for accommodation of a hangar and for mounting the catapult to launch the aircraft and a crane for their recovery.
- (X) BRIDGES – PROTECTION, SIGNALLING ARRANGMENTS,
NIGHT-FIGHTING ARRANGEMENTS, ETC.
Protection.
Bullet proof protection to all exposed personnel.
General Arrangements.
The essential requirement is protection from wind and weather; it is considered that full protection under action conditions should be provided.
Signalling Arrangements.
Essential requirements.
- (i) High and clear hoist for flags.
Desired requirements.
- (i) Concentration of visual signalling equipment on one deck in order to:-
- (a) Economise in apparatus.
Night Fighting Arrangements.
The arrangements in NELSON Class are considered to be satisfactory. It is desirable to have the torpedo control on the Captain’s bridge if this can be done without undue crowding.
_______
- (XI) NUMBER AND DISPOSITION OF SEARCHLIGHTS.
In former designs searchlights have not been included amongst the preliminary requirements, so that it may be convenient, in deciding upon the equipment to be provided to discuss the purposes for which searchlights will be required.
2. In addition, some mention must be made of the various considerations governing the positioning of the lights in the ship and the methods of using them, observing that it seems possible that certain erroneous ideas crept in during the years following the War, and have not come to be accepted as facts
3. Searchlights are carried in capital ships with three objects:-
- (a) To light up enemy vessels in order that they may be destroyed by gunfire. For this purpose arrangements are necessary to enable two targets on the same side to be illuminated simultaneously.
4. Remarks on the positioning of Searchlights.
The positions of the searchlights in the Fleet to-day are the result of the recommendations of the Grand Fleet Searchlight Committee, who were assembled after the Battle of Jutland to consider what improvements could be made in the Searchlight Installations of the Grand Fleet.
5. The following points stand out amongst the conclusions reached by the Committee:-
- (a) Efficiently controlled Searchlights combined with rapid fire present the greatest difficulty to the attacking vessels in the opinion of our Destroyer Officers, though they are of assistance to Destroyers, not actually under fire or illuminated, in providing them with a definite point of aim.
6. It was reported by the Battle Cruiser Fleet Committee, at the same time, that the use of two Searchlights, widely separated, gives away the position of the ship and her alterations of course, and it was noted, in the case of SOUTHAMPTON, who was burning two lights well separated, that the majority of the damage she sustained occurred between the lights.
7. Due weight must be give to the views of this Committee which was assembled with the incidents of the recent Battle fresh in their minds. It is considered now, however, that the recommendations concerning the positioning of the lights must have been heavily influenced by the fate of H.M.S. SOUTHAMPTON.
8. This ship, leading her Squadron, encountered an enemy Cruiser Squadron of five ships on a converging course. SOUTHAMPTON switched on two searchlights, on aft and one forward, whereupon five German ships also switched on their lights. The other three ships of the Second Light Cruiser Squadron did not switch on Searchlights but used the enemy lights as a point of aim. The five enemy ships concentrated their fire on SOUTHAMPTON and the Second ship with the result that the whole of the upper works of SOUTHAMPTON suffered very severely. Damage was not confined to the vicinity of the forebridge although it was remarked that the majority occurred between the two lights.
9. Numbers and Positions of Searchlights proposed.
In order to meet the requirements set out in paragraph 3 above, it is considered that 3 Searchlights should be provided each side.
One light each side must be situated forward near the forebridge, and two lights each side on platforms near the funnels, well clear of blast, with as much arc of forward training as possible, and capable of covering arcs up to the stern.
10. Remarks on positions proposed.
- (a) In recommending that two searchlights should be fitted forward, SOUTHAMPTON’s
action has been borne in mind, but it is considered that he importance
of being able to locate, engage and dazzle destroyers coming in
to attack from forward bearings before they reach their firing
point, without the existence of any blind arc, outweighs the disadvantage
of providing a point of aim near the bridge.
The decision to burn a Searchlight and so provide a point of aim at all is the vital matter and, under night conditions, there is no reason to suppose that the damage from destroyer gunfire will be caused at the actual point used as an aiming mark. In point of fact, one part of the ship is just as likely to suffer as another.
It is not desirable, however, that the forward Searchlight should be used for purposes other than repelling torpedo attacks developing from ahead.
(b) In order to meet requirement 3(a), it is desirable, in order to provide satisfactory illumination, that the directors who will use the searchlights, and the controllers who will lay the lights, should be in the same relative position to the projectors. In the case of the forward Searchlights, this points to the desirability of their being placed as far below the control position as possible, subject to sufficient freedom from blast being provided.
This lower position will have the added advantage of giving illumination over a large area, owing to the beam being nearly horizontal.
11. Control Positions.
It is considered that one control position should be provided each side, each position being provided with two controllers.
The forward controller should be connected to the Searchlight fitted near the forebridge or to the forward Searchlight on the funnel structure, by means of change over arrangements, and the after controller should control the after light at the funnel position.
The control position should be place don or near the forebridge, in close contact with the Captain and just abaft the Captain’s E.B.I. (Note:- The control position in NELSON is reported to be very satisfactory).
Arrangements must be made for the forward controller to have a clear arc of vision up to 2º or 3º across the bow.
12. Stabilising Arrangements.
All Searchlights should be stabilised both in azimuth and elevation. Stabilisation in elevation is of the greatest importance, since the firing of the main armament always causes ship to heel. If stabilisation is not provided this heel throws Searchlights off the target just at the moment when the operator is blinded by flash and smoke, and is unable consequently to apply the necessary correction to the sight.
13. Use for A.A. Defence.
It is desirable that one Searchlight each side should be capable of use against aircraft up to 70º of elevation.
14. Summary of Proposals.
- (a) The Searchlights should be capable of use on any bearing, from right ahead to right astern.
_________
- (XII) CONNING TOWER, NUMBER OF CONTROL POSITIONS
AND APPROXIMATE LOCATION FOR EACH TYPE OF
GUN ARMAMENT.
Conning Tower.
In view of the fact that all control positions are protected, and assuming that bullet proof protection is provided for the bridge as proposed, there do not appear to be adequate grounds for fitting a conning tower.
Owing to the poor view obtained, there has always been great reluctance to use this position in any case. So far as the protection it affords is concerned, it is almost certain that a direct hit would place the enclosed personnel out of action; for splinters no such protection is necessary.
Steering, etc., are now carried out from a lower conning tower; Captain, Navigating Officer, etc., will be behind bullet proof protection on the bridge [sic]; control personnel are already protected, and it is therefore proposed that no conning tower be fitted.
Control Positions.
See under Sections (I) to (III), heading 7.
_________
BRIEF SUMMARY OF MAIN CHARACTERISTCS OF
1937 CAPITAL SHIP
1. Disposition of Main Armament
Not less than 4 twin turrets, placed as in QUEEN ELIZABETH Class.
2. Calibre and Disposition of Secondary Armament.
12-6” guns in battery mountings, capable of 30º elevation.
3. Anti-Aircraft Armament.
6 guns each side, or 2 twin mountings each side and one on centre line.
Design of ship to be such that 4.7” or 4” can be mounted; decision as to which calibre to be given later.
To be mounted in Between Deck Twins.
5 Mark M Pom Poms and 8, 0.5” Multiple Machine Guns if possible; a minimum of 2 Pom Poms and 4 Multiple Machine Guns if it is necessary to reduce numbers.
4. Torpedo Armament.
Torpedoes to be carried; above water tubes, quintuple mountings.
5. Armour Protection.
- (a) If displacement is not reduced, 1928 proposals to be accepted, i.e., against 16” shell and 2,000 lb. bomb; but protection to be given to machinery spaces against 1,000 lb. “Terminal velocity dive” bomb attack.
6. Under-water Protection.
- (a) Anti-Torpedo. Against 1,000 lb. charge in contact with the ship’s side.
7. Speed.
A maximum of 23 knots.
(Endurance required at various speeds is detailed.)
8. Endurance.
14,000 miles @ 10 knots.