REFERENCE DOCUMENTS & RESOURCES - OFFICIAL ADMIRALTY DOCUMENTS
ADM 1/8586/70: FINAL REPORT OF THE POST-WAR QUESTIONS COMMITTEE (1920)
Updated 16-Mar-2007
This document is a modern transcription of Admiralty record ADM 1/8586/70. It concerning naval lessons learned from the First World War. It was transcribed by David Chessum on behalf of the the Royal Navy Flag Officers 1904-1945 website. The original file is held at the The National Archives at Kew, London. This Crown Copyrighted material is reproduced here by kind permission of The National Archives.
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REPORT ON PARAGRAPH 3 OF TERMS OF REFERENCE.
“3. To consider and advise as to the main naval requirements of each type, e.g., speed, endurance,* armament, protection, displacement, special fittings, and equipment, etc., giving reasons for each requirement. In so doing, to investigate thoroughly and report upon the naval and tactical considerations arising out of:-
(a) The increased efficiency of projectiles over armour;
(b) The increased efficiency of hull protection against the effects of torpedoes;
(c) The part likely to be taken in future by aircraft, both in attack and defence.
(in connection with (a) and (b), certain secret papers will be referred to the Committee).”
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Report on Paragraph 3 of Terms of Reference is dealt with under the following headings:-
The BATTLESHIP.
The BATTLECRUISER.
The LIGHT CRUISER AND CONVOY CRUISER.
The FLEET AIRCRAFT CARRIER.
The DESTROYER AND FLOTILLA LEADERS.
The SUBMARINE.
P. and P.C. BOATS
C.M.B.’S.
D.C.B.’S.
General remarks on:-
Armament.
Machinery.
Fuel.
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INDEX TO THE BATTLESHIP.
GENERAL CHARACTERISTICS |
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SPEED |
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MAIN ARMAMENT |
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*Admiralty letter M.03895 of 26th July, 1919 |
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INDEX TO THE BATTLESHIP – continued.
MAIN ARMAMENT –continued. |
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SECONDARY ARMAMENT |
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ANTI-AIRCRAFT ARMAMENT |
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STAR SHELL GUNS |
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SEARCHLIGHTS |
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TORPEDO ARMAMENT. |
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INDEX TO THE BATTLESHIP - continued
GUNNERY AND TORPEDO CONTROL POSITIONS. |
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CONNING TOWER |
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PROTECTION. |
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INDEX TO THE BATTLESHIP - continued
DISPLACEMENT. |
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SPECIAL FITTINGS AND EQUIPMENT. |
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THE BATTLESHIP.
GENERAL CHARACTERISTICS.
1. Importance of Protection and what it embraces.
As the first point to be included under the heading of “General Characteristics,” we wish to emphasis the importance of protection in its widest application, that is to say, the arrangements provided to keep a ship afloat in spite of sever damage from any weapon which may be used against her. In our opinion, a ship is of no value as a Capital Ship unless she is capable of receiving heavy blows without sinking, blowing up, or loss of motive power, and of being kept upright in spite of underwater damage, and thus of continuing to steam and fight and being able to give and receive further punishment without the disadvantage caused by heel. From these requirements others follow as a matter of course; these include good torpedo protection and water-tight subdivision, which should be as uniform as practicable throughout the ship; strong and well-supported bulkheads, which can be relied upon to remain water-tight when the compartment they enclose is flooded; facilities for rapidly correcting heel and, more slowly, for correcting trim; pumping power sufficient to deal with considerable leakage through damaged bulkheads and decks.
2. Relation of Size and Form to Protection. – Unless the design and equipment of the ship are such that she can be considered to be safely protected from under-water attack, size should be limited in order to reduce the torpedo target and lessen the magnitude of the disaster in case she is lost. Likewise special attention should be paid to manoeuvring powers in order that she may be able to avoid torpedoes If, however, safety against under-water damage is made the first consideration in the design, then length and handiness to manoeuvre may come second.
3. Gun Platform. – The ship should be a good heavy gun platform whatever her size.
4. Limitations to Beam and Draught. – In order that the Constructive Department at the Admiralty may be in a position to produce the best designs for new Capital Ships, we strongly recommend that the limitations as to beam, which have hitherto handicapped us, be removed to the fullest possible extent. We are informed that the limiting beam for ships using the Panama Canal is 106 f. and the beam of the new U.S.A. battleships of the “ Connecticut” class and battle cruisers of the “ Lexington” class, 106 ft. and 105½ ft. respectively, confirms this figure. We consider that this limit should be adopted for our new capital ships, and, with it, a reduction in draught to 30 ft. in the deep-load condition, or to such draught in the future as will permit of passage through the Suez Canal. With these dimensions, both of the principal artificial waterways of the world will be open to our ships, a factor which may be vital in a future war. But, apart from the above, increased beam and decreased draught of first-rate importance as affecting design and stability, while decreased draught also confers navigational and possibly operational advantages. The wider ship is more easy to protect structurally against under-water damage because of the greater space available, stability is likewise improved by the larger beam; speed will not suffer by the change in shape if we can judge by results in “Revenge” class or the speed of German battleships.
5. Docks. – We realise that the policy recommended above is a serious one from the point of view of our existing docks, but, after full consideration, we do not think this should be allowed to weight against it; the advantages to be gained in the matter of ship efficiency are so far-reaching that we feel the step to be an essential one. It follows that, if our proposals are approved, orders for new floating docks will be required at the same time as those for new capital ships.
The Portsmouth floating dock, having a lift of 32,000 tons, cost £258,000 in 1914, of £8 per ton lift; the same dock would now probably cost three times as much. Allowing £6,000,000 for the cost of a new battleship, a floating dock with 50,000 tons lift could be built for approximately £1,200,000 or 20 per cent. of her cost.
6. The serious disadvantages of being without adequate docks was shown clearly in the early months of the war before the floating docks were taken to Invergordon and the Tyne, and the Rosyth docks were completed. Had they not been available
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the Fleet could not have been kept so efficient, ships proceeding to distant ports to dock would have been unavoidable exposed to additional dangers from submarines and mines, and much delay must have taken place in getting ships repaired after damage.
7. Displacement. – We should prefer a ship having a displacement of approximately 35,000 tons in the deep-load condition, but fully realise the figure can only be determined after all the main characteristics of the ship are decided; it is mentioned, therefore, as an indication of what the Committee consider to be desirable.
8. Experimental Ships needed to Test Designs. – So much has occurred during the war to show up old weaknesses in our material and to improve destructive agents of all kinds, that we believe extensive trials are needed to prove or disprove new theories of ship design. We recommend, therefore, that two of the older battleships most suited for the purpose be selected for experimental work in connection with construction and protection and all that these involve. The lessons learned would not be only defensive. Weapons would improve as a result of severe practical tests. That there is a need for such tests is borne out by the facts that it was only after Jutland that we realised our heavy projectiles needed improvement, and that our magazine protection was dangerously inadequate.
9. Summary of Main Characteristics. – The principal features which should be found in the design of a battleship are discussed at length under their separate heads in the remarks which follow, but, broadly, they may be summarised as follows:-
The design should be such that the ship is strong in all essentials; no primary characteristics should be sacrificed for a secondary one. In armament, protection, endurance, speed and equipment she should compare favourably with contemporary foreign ships she need not necessarily be superior in each of these, because in order to keep down cost, displacement and therefore dimensions must be moderate. The conception takes the form of the “Royal Sovereign” class, but with improvements, as described hereafter.
10. Report follows Terms of Reference. – The order in which the main naval requirements of the battleship are dealt with is similar to that in which they are given in our Terms of Reference.
SPEED.
11. Reason for High Speed. – Superior speed always confers advantage for tactical reasons; high speed greatly increases the mobility of a Fleet. In war it is always the unexpected that happens; battle at sea is largely a contest of wits, and it is impossible to foresee every eventuality. At Jutland, for example, the manner of the Battle Fleets meeting was uncertain up to the last moment and, after contact was made, rapid deployment was of supreme importance to the British Fleet. The larger the Fleet the more important becomes speed, or the whole becomes unwieldy, due to the time required to form line of battle. Thus the wing columns, which will probably be composed of the newest and most powerful ships, need some excess over the older ships in the centre; otherwise new battle tactics need devising to compensate for unavoidable delay in deployment.
12. Speed Recommended. – We recommend at the present time a speed of 23 knots for the Battleship, this being a slight advance on the “Revenge” class, although not as much as in the “Queen Elizabeth” class. It is also the designed speed of the new U.S.A. battleships. In our opinion, our ships must have at least equal speed to those of foreign navies.
13. Relation of Speed and Draught. – This speed of 23 knots should be obtained in the deep, i.e., the real normal load condition, which should imply full sea-going complement and equipment of ammunition and stores, but with only two-thirds fuel on board. Speeds obtained at lighter draughts may by valuable for constructive and engineering purposes as affecting designs, but they are only misleading in working out tactical and strategical problems.
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ENDURANCE.
14. Reason for Large Endurance. – The two strongest foreign Naval Powers are now the U.S.A. and Japan. War against either would entail operations at a great distance from home and probably also at a distance from the main Fleet base.
Whatever be our relations with these countries, we should possess a Fleet capable of guarding our interests in any part of the world, and it is incumbent upon us to design ships for that purpose.
15. Endurance Recommended. – We recommend, therefore, that our battleships should have an endurance amply sufficient to steam across the Atlantic and back, or from Canadian Harbours to the West Indies and back; or from Singapore to Japanese waters and back; and put this at 6,000 miles.
We recommend 14 knots as the speed to be used for calculating endurance, giving a fleet speed of 13 knots on passage.
It should be noted that the official endurance is 15 per cent. less than the maximum distance which can be steamed for the total quantity of fuel carried, this margin being allowed for unfavourable weather and for fuel which is unavailable, e.g., the oil fuel pumps will not take the tanks down to the last ton or so. Thus a ship having an official endurance of 6,000 miles must carry fuel sufficient for rather more than 7,000 miles.
If 15 per cent. of the displacement be taken as being as much as can be allotted to fuel in a battleship, a ship of 35,000 tons can carry 5,250 tons, which should be more than sufficient to steam her 7,000 miles at 14 or 15 knots. This is based on the consumption of “Royal Sovereign” and “Queen Elizabeth” classes being 10½ tons per hour at 15 knots, and takes into account a heavier ship but with improved economy owing to geared turbines.
MAIN ARMAMENT.
16. Policy. – We consider that it would be very erroneous policy to permit any foreign navy to out-gun ours.
By out-gunning is meant the power, firstly, to hit hard enough to diminish an opponent’s fighting power and, secondly, to hit frequently enough to destroy it.
17. The out-gunning of one ship by another does not necessarily follow because her guns are of larger calibre, or because they are more numerous; but, with the continuance of fairly uniform progress in gun armaments by all nations, we should be very sure of our ground before allowing other navies to get ahead of us in either respect. The probability is that, within reasonable limits, a ship mounting heavier guns or a greater number of guns of equal calibre than her opponent will have the advantage. It has generally happened that, with an increase in calibre, the number of guns or number of turrets, or both, has been reduced. Consequently the adoption of a 16-in. gun and triple-gun turrets by the U.S.A. for their new battleships is a notable development.
18. Factors affecting Strength of Armament. – If we could fix on a certain thickness of armour as being the maximum likely to be employed in a ship for some years to come, and if we also decided the maximum range at which we wished to be able to penetrate this armour, the minimum calibre of gun necessary to do the work could be determined. Having arrived at this, and knowing approximately the weight of main armament which can be carried for any particular size of ship, various armaments could be compared.
In practice, however, decision as to armament is always affected by other considerations, the principal one being armaments of foreign ships. A natural tendency exists to go one better, especially in calibre, in the belief that the heaviest gun is the most likely to be successful when put to the proof. But there is a limit to this because no one would agree to the adoption of such a large calibre that number of guns become disproportionate, e.g., two 24-in. for eight 15-in.
We have to recognise, therefore, that the result is always a compromise and is always likely to be, even if radical change in gun design materialises, for this would soon be universally followed.
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19. Possibility of New Developments in Gun Design. – An example of radical change in gun design was furnished during the war by the German long-range guns which bombarded Paris at a range of 75 miles.
These guns are of 8.28-in. calibre, are believed to have had a muzzle velocity of 5,000 f.s., and fired a rifled shell of very pointed shape (10 c.r.h.). The high velocity could only be attained by high pressure and a shell light in proportion to the gun and weight of propellant; therefore the gun was much heavier and much longer than normal for the same calibre, while the shells were made of specially strong (zirconium) steel.
It would be unwise to dismiss guns of this type as freaks, because, whatever their disadvantages in respect to accuracy and the small burster which can be carried in their shell, they do mark a definite stage forward in the attempt to increase the power of the gun.
In the following paragraphs, which deal with naval guns of the present time, endeavour is made to analyse gun power, and ti will be seen how much importance attaches to high velocity as a means of obtaining a large danger space and, therefore, of hitting, and a high striking velocity in order to penetrate armour.
It would be premature to say that the limit to calibre is in sight, but at the present rate of progress it cannot be very far distant. When it is reached, or more probably before, means will almost certainly be found to increase gun power in some other way. The obvious way is by increasing muzzle velocity, which is what the Germans did.
The invention of the rifled B.L. gun in the days of muzzle loaders was the last great step forward; the next is hardly likely to be so revolutionary.
In the belief that progress must ultimately lie in the direction indicated, we recommend that research on these lines be commenced, quite irrespective of the trials we have recommended in paras. 25 and 31 for guns of normal design.
Calibre Considerations.
20. Meaning of Gun Efficiency. – The first thing to be decided is the power requisite for the individual gun; that is, its efficiency as an engine measured by its ability to hit with the shell it discharges and the ability of its shell to penetrate and to destroy.
There is no difficulty in working gun machinery. What men of one nation can do those of another can, but nationality and training really tell under fire. If the gun is not the best, the most efficient and the most modern, and is put against one that is, too much is being asked of the human element, whatever the result may be.
21. Ability to it depends on range, accuracy and danger space; to penetrate on armour-piercing qualities; to destroy on the destructive effect of the shell burst. These will therefore be considered separately.
22. Range. – There is no doubt that the 15-in. gun and ship’s mounting can be developed to give the maximum range required for ship versus ship action.
23. Accuracy. – Accuracy has two sides: the absolute accuracy of the gun, as determined on the proving ground, and the accuracy of the armament in the hands of the personnel.
As regards the individual gun, it is highly probable that the larger the gun the better the accuracy. This is not only based on experience, but the effect of manufacturing inexactitudes is proportionally less, and the ballistics are more stable because the projectile is less affected by wind and other external causes.
As the accuracy of a gun is measured by its performance, the accuracy of the projectile and propellant have to be taken into consideration. These are dealt with elsewhere in our report, but may be mentioned here because the regularity of internal ballistics depends upon the propellant. With a low muzzle velocity, as given to the 15-in. Mark I, accuracy is good, either because the vibrations set up in the chase on firing are insufficient materially to affect the steadiness of the flight of the shell, or because a low mean difference of velocity between rounds can be obtained (2 f.s.); with a higher velocity, vibration will be greater and a larger mean difference in
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velocity from round to round must be expected, accuracy will therefore fall off. The point is that the gun, projectile and propellant are one, and to get the best result from the gun the ammunition must be suited to it.
The accuracy of the armament in the hands of the personnel is remarked upon in para. 39.
24. Danger Space. The figures for the existing 15-in. gun are low and could be improved by reducing the weight of the shell so as to obtain a higher muzzle velocity; but this advantage will be gained t the expense of burst effect, and possibly of accuracy and life of gun. What can be done with a 15-in. gun can be done also with larger calibres, so the latter will retain other advantages they already possess.
So far as we are able to judge, the best obtainable danger space figures for new designs of all calibres, 15-in. to 18-in., with normal as opposed to exceptional ballistics, would not differ appreciably form one another (although decidedly superior to the 15-in. Mark I) and, therefore, from this point of view, there is little or nothing to choose in respect to calibre.
We wish to emphasise, however, that every yard of danger space is so valuable, especially at long ranges, that it is a factor which should always be given great weight. The reasons are that it minimises the effect of errors in sighting and compensates also for inaccuracy. The former is self-evident; the latter is explained by the relations between danger space and the 50 per cent. zone, for, if the zone is 300 yd. a danger space of 30 yd. must give more hits than one of 20 yd.
25. Armour-piercing Qualities. – These have become very difficult to forecast for various reasons, which are briefly stated below.
For a long time progress in the attack or armour by shell was so slow that armour improved in quality at a greater rate, culminating with the introduction of K.C. armour. During this period various formulae were built up to enable penetrations and resisting powers to be calculated, but only normal impact was considered.
It was generally agreed that striking energy was the principal factor in obtaining penetration, and thus, for any two shell with approximately similar striking velocity, the heavier had the advantage.
With the introduction of larger calibre guns, immense improvement in shell, and a wider outlook on the question generally, including the attack of armour by shell striking at angles to the normal, these old formulae have been shown to be obsolete, and up to the present insufficient trials have been carried out to enable new formulae to be constructed. There is therefore now no recognised accurate method of assessing results of hypothetical guns and shell; trial si the only means by which reliable information can be obtained.
Such trials as have been carried out do show, however, that striking energy may be by no means f the same dominating importance that it used to be; better results have been obtained by combining with a high striking velocity a design of shell able to resist the stresses set up on impact with armour. Long, i.e. heavy, shell are more difficult to get through an inclined plate that shorter, i.e. lighter, ones because the base may be wrenched off in the effort of the shell to turn in the plate. A 13.5-in., 1,250-lb. APC. shell is just as good, if not better, than a 13.5-in. 1,500-lb APC. Shell against a plate at 20 deg. to the normal, in spite of lesser striking energy.
The fact is, we don not know what relation between the weight and diameter of a shell is best for all-round A.P. qualities and, until this is known, we cannot really decide the best design of shell for our heavy guns. Nor do we know the limit of calibre beyond which A.P. qualities fall off on account of the size and length of the shell.
The difference in weight between the shell supplied to British and German 15-in. guns, 1,920-lb. and 1,653-lb. respectively shows what different views are held as to the best method of obtaining maximum efficiency from heavy guns.
26. In spite of what has been written above, in default of anything better there is no alternative but to make us of the old methods of calculation in the belief that figures deduced from them are better than nothing.
The muzzle velocity of our 15-in. gun is low compared to some foreign guns, the U.S.A. 16-in. for example, and although it fires a relatively heavier projectile, its calculated penetrations are decidedly smaller, e.g., 14.1 in. at 15,000 yds. as against
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19.6-in. (See table in next para.) Our 15-in. has actually penetrated 10-in. at 20 deg. to the normal at 15,000 yds. An improved design of 15-in. gun would undoubtedly obtain better results, but these will not quite come up to the U.S.A. 16-in.; an the latter improved would probably retain much the same margin of superiority. We understand that U.S.A. shell are equally as good as ours, so that we have nothing in hand in that respect. There is, however, no object in mounting guns which are unnecessarily powerful, and this appears to be the critical factor. With armour far behind the gun in efficiency, ships cannot carry it either of sufficient thickness or in sufficient quantity to keep out modern shell. We think it probable that armour and methods of disposing it will improve, but there is no immediate prospect of the former and it is also probably that guns and shell will improve. Our 15-in. Mark I gun, as already shown, is distinctly inferior in penetration to the U.S.A. 16-in. and, allowing that ships can quite will carry side armour 14-in. thick abreast their vitals (“Baden” has 13¾-in.), it is not capable of delivering a knock-out blow at ranges greater than 15,000 yds.; this range for the American gun is well over 20,000 yds.
27. Table showing Calculated Penetrations of K.C. Armour.
Gun. |
10,000 yds. |
15,000 yds. |
20,000 yds. |
25,000 yds. |
15-inch Mark I (as now mounted in H.M. Ships.) |
17.7” At 7° |
14.1” at 13° |
11.5” at 21° |
9.6” at 31° |
15-inch 50 calibre |
22.5” at 5° |
18.9” at 9° |
16” at 14½° |
13” at 22° |
16-inch American |
23.4” at 5° |
19.6” at 9° |
16.4” at 14° |
13.3” at 21° |
16-inch New Gun |
23.9” at 7° |
20.3” at 9° |
17.3” at 14½° |
14.3” at 21½° |
18-inch Mark I (“Furious” Guns) |
21.8” at 7° |
18.7” at 12½ |
15.1” at 19° |
13.8” at 27° |
18-inch New Gun |
25.5’ at 6° |
22.1” at 10° |
19’ at 15° |
16” at 22½° |
As already explained, this table is not reliable and the figures it gives cannot be checked with certainty except by actual trial. It shows, however, what great advantage the heavier guns possess theoretically.
28. Burst Effect. – This depends on size of shell, nature and weight of burster; obviously, if gun and shell designs are normal, and bursters of similar explosive, the heavier gun fires the heavier shell and gets the advantage. But burst and A.P. qualities to some extent conflict because, if shell are made very strong in order to penetrate armour, their fragmentation on bursting may be poor.
29. Summary. – To obtain results from a 15-in. gun comparable to those from a 16-in. or larger, the 15-in. must either be forced or lengthened to increase muzzle velocity, or some radical change in ballastics must be made. A forced gun loses in accuracy, which means loss of hits. If the length of a 15-in. gun can be increased, so probably can that of a larger, consequently the gain will be similar; it is merely a question of whether the increased weight necessitate by greater length gives results sufficiently better to justify it. There is no immediate prospect of radical change in ballastics materialising; it would need several years to investigate and try to a conclusion.
Research and experiment carried out on a large scale may prove that there is limit of calibre and length beyond which there is no advantage n going, or which is imposed for manufacturing reasons. Difficulties have in fact already been experienced with ammunition for the 15-in. gun, and the plant now available in the country is inadequate to manufacture guns of much increased calibre in numbers; but we are on the way to overcome the former and the latter is only a question of outlay. No sufficient reason is see to suppose that the limit of calibre of maximum efficiency has yet been reached.
30. Other Arguments which may be cited for and against increase in calibre include the following:-
For:- The moral effect of the heavier gun is considerable, not so much perhaps in action (because few see what is going on) but as engendering confidence in the material and in the forethought at the Admiralty. Officers and men do not doubt their ability to make the most of the material provided but they do undoubtedly compare that material with that of other ships, and especially foreign ships, which they may have to fight. This
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argument can, of course, be exaggerated unless equality is assumed in some respects, for example a 15-in. gun able to penetrate the enemy’s armour t any range, firing tie as fast and having twice as much ammunition as (say) an 18-in. gun would be a better weapon for a ship.
We think that, during the war, the 13.5-in. and 15-in. gun ships were of great moral strength to us, for we know that the German personnel with their 12-in. guns felt themselves inferior in spite of all that was told them to prove the contrary. Von Tirpitz completely failed to convince German naval opinion on this point.
Against: - Increased calibre by one nation has inevitably led to others following suit. Both the U.S.A. and Japan have adopted a 16-in. gun, and it is said that the U.S.A. is making an 18-in. or it ma be a 20-in. gun for trial. If we join in the competition, we may be forced to follow step by step, or we could take the lead by making a large increase, in the hope that this will prove to be the limit for a number of years.
With small guns weight is less all round, thus, affecting size of ship and reducing expense. If size of ship and cost are of secondary importance more guns might be carried for the same weight.
Manufacture and supply of ammunition is simplified by adherence to one calibre for as long as possible; where supply involves transport over long distances by sea, standardisation pays both economically and practically because occasional delays or losses of transports will not be of supreme importance. From this point of view it is also better to take one large step instead of several smaller ones.
Peace cost for practice ammunition and replacement of guns will be smaller.
31. Conclusion. – We consider that the 15-in. gun now mounted in H.M. ships is insufficiently powerful to be pitted against the latest foreign guns.
We consider, therefore, that the right policy is to increase calibre so that our guns may at least equal those of foreign Powers in range, danger space, and armoured penetration, whilst at the same time retaining accuracy.
We think that it would be wise to commence at once investigation of an 18-in. gun, even if there is no immediate intention to adopt it. It is not as if an 18-in. gun had not already been built; the step has been taken and is therefore more likely to be followed by other nations. By doing so we should gain information which will enable us to build efficiently if we need to, and will be nearly as valuable for new guns of a rather smaller calibre if this be ultimately decided upon.
We recommend, further, that trials be initiated at once with the 15-in. gun in order to obtain full information on the relative merits of heavy and light shell within wide limits, which may serve as a guide for the heavier gun, and, if the results are important, might also enable us to re-arm our 15-in. ships with shell of superior types.
The Gun Mounting.
32. Maximum efficiency cannot be obtained from the gun unless its mounting and all that this includes, are capable of supplying it with ammunition at a uniformly rapid rate, or enabling it to be trained and elevated with precision, and of permitting adjustments to be made to correct for inaccuracies peculiar to an individual gun or its ammunition.
33. Rate of Fire can only be judged comparatively; there is no theoretically best. It has always been recognised as a factor of primary importance because rapid hitting breaks down the enemy’s resistance; the war showed that with fairly evenly-matched ships nothing short of maximum rapidity was sufficient for success.
At the present time it is generally recognised that the rate of loading obtainable from a 15-in. turret is a few seconds slower than from a 13.5-in., and from a 13.5-in. than from a 12-in. This, no doubt, is due in part to the heavier weight of moving parts all through the turret, but there is reason to suppose there are other causes.
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34. Speed of Loading depends upon Design of Machinery and Power available to work it. – There is no uniformity either of turret machinery design or source of power amongst the Navies of the Great Powers; each has its own designs and the power use may be hydraulic, electric, pneumatic, or a combination of the three. The fact that differences exist shows that finality has not been reached.
In our Navy, the introduction of director firing led to difficulty being experience in maintaining hydraulic pressure, due to the number of machines put in operation simultaneously in order to reload after each salve. The older ships were undoubtedly under-pumped and, in order to improve matters, pneumatic run-out has been substituted for hydraulic in a number of mountings. But this does not afford a complete explanation, because the design of the pump and its steam engine does not lend itself to maintenance of high pressure under very variable loads; its speed falls so low that it does not respond sufficiently quickly to sudden large demands.
Another point is that, unless each turret has its own pump, some turrets are nearer the source of power and therefore better supplied than those more distant. Again, all turrets are not on the same level and it stands to reason that there must be greater loss of pressure in the longer pipes of the higher turrets.
35. Arrangements for Transport of Ammunition. – The transport of ammunition will affect rate of loading only in any portion of it has to be man-handled; at present, all cordite is man-handled in the magazine and handing room. For the 15-in. Mark I gun the weight of the charge is 428 lb., made up in four quarters for convenience. These 107-lb. charges are about the limiting weight for man-handling. An 18-in. charge would weight 700 to 800 lb. If calibre is increased, therefore, either the charge must be made up in sixths or power working must be adopted in the magazines and handing rooms.
36. Training Machinery is not at present satisfactory as trouble is experienced, especially in the heavier turrets, with the long spindles and frictional gear. The control is good.
37. Elevating Machinery and Control. – We believe these to be very efficient and have no suggestions to make in respect of them.
38. Summary. – We do not think that a heavier gun than the 15-in. can be ruled out on the grounds of insufficient rapidity until it has been proved that it is impracticable to provide machinery to load it sufficiently quickly.
39. Accuracy of Armament. – As, in practice, guns are not fired singly, hits depend less upon the accuracy of the individual gun than upon the accuracy of the armament as a whole That the latter is much less than the former is shown by the very small percentage of hits obtained to rounds fired. The causes and effects of inaccuracy when the whole or part of the broadside is fired simultaneously are therefore important.
Hits are obtained by correcting the sights after seeing the fall of shot, and the fact that the broadside has “spread” assists this correction. If spread is very large, hits per salvo will be few, or even nil, because the target may be straddled without being hit. If the spread is nil, few hits will be obtained, owing to the difficulty of placing the mean point of impact exactly on the target. Consequently, some minimum spread or dispersion is advantageous.
Spread is affected by the accuracy of the individual gun, the accuracy (or calibration) on the broadside and the average error of the personnel. Considering existing guns, spread is larger than the most advantageous minimum, which is generally held to be 150 to 200 yds. It is not sufficient for the individual gun to be accurate if our methods of calibration are not; in the widest sense, calibration includes allowances for decrease of muzzle velocity due to wear, temperature of magazines, etc. The error of the personnel, which is invariably the largest of the tree, varies with the skill and knowledge of the personnel, and of the control personnel, in a special degree.
So far as ship design is concerned, no more can be done than to provide control positions, which are the best that experience can evolve, and efficient arrangements for controlling magazine temperatures.
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Considerations respecting Number of Guns.
40. The number of guns which can be carried by a ship is governed by their weight (equals calibre) the manner of arranging them, the displacement and other primary characteristics. Because volume of fire is of first importance, the number of guns should be as large as possible.
41. Minimum Number for Efficient Fire Control not the Deciding Factor. – For efficient fire control the least number of guns which should fire in each salvo is four; this necessitates a ship carrying eight guns. But it is not sufficient to accept this; the real question is what number are needed to prevent a ship being out-gunned by a foreign contemporary. As the director system is no longer exclusive to us, our fire control methods are known in their entirety to the U.S.A. Navy, and as we have no reason to think that our gun mountings are capable of more rapid fire than those of other navies, it follows that we shall be out-gunned unless we either have an equal number of guns or mount a smaller number in a more efficient manner.
42. Number of Turrets carried in Modern Ships. – To judge by recent construction, both at home an abroad, it appears to have been more or less accepted that four turrets is as many as can be built into a Capital Ship without unduly increasing both size and cost or sacrificing some other very important characteristic, and that two of these turrets should be forward of the machinery and boiler room spaces and two aft.
43. This arrangement is a development founded on experience of earlier types such as “Dreadnought” and “Indomitable,” “ Neptune,” “Orion” and “Lion,” and finally “Repulse.” The fifth centre-line turret, which first appeared in “Orion” class and was continued in later classes mounting 13.5-in. guns, was an undoubted advantage from the point of view of offensive power; but, with the introduction of the 15-in. gun and at the same tie a demand for higher speed, it was omitted from later ships in order to keep down size. All navies have been faced with this problem and although some, notably those of the U.S.A. and Japan, adhered to a fifth or even a sixth turret for some of their later designs, each now appears to have come round to the four-turret battleship, eg., U.S.A. “Colorado,” “South Dakota” and “North Carolina” classes (10 ships); Japanese “Kaga” class (four ships); Italian “Caracciolo” (one ship); German “Baden” (two ships).
44. Recommendation. – However desirable the four-turret design may be for constructional reasons, we consider that these must be subordinated to military reasons if we are unable to mount efficiently in four turrets the number of guns required. Should this prove to be the case, we think that if a six centre-line turret design is altogether impracticable for the ship of the size we are recommending (approximately 35,000 tons displacement), a gun margin against us of not more than 12 guns in four triple-gun turrets to 10 guns in five pair-gun turrets should be accepted. Although gun power would be less, there would be advantage in distributing the armament into a larger number of separate units.
45. Number of Guns mounted per Turret in Modern Ships. – Like our ships, all the foreign battleship mentioned in para. 43 have pair-gun turrets with 15-in. or 16-in guns, except the six U.S.A. ships of “ South Dakota” and “ North Carolina” classes, which are to have triple-gun turrets. These however are not the first vessels to be so armed, since the triple-gun turret was a feature in the design of earlier U.S.A. ships as well as in Austrian, Italian and Russian.
Note. – The latest projected French battleships were to have four-gun turrets; the designs must have been worked out.
46. Triple-gun Turrets. – Unfortunately we have very little reliable evidence upon which to base an opinion as to the practical advantages of triple-gun turrets. None of the ships mounting them have been in action during the war and we know nothing of the results of their target practices. Years of experience with the pair-gun turret have enabled us to produce an efficient type, easy to maintain in good order, simple to manipulate, and capable of prolonged working at a uniform and rapid rate of loading; doubtless, many improvements can still be made, especially in speed of loading, but taken generally and relatively to foreign navies, these claims do not exaggerate. The preference for the pair-gun turret has not been altogether conservatism; designs for a triple turret have been considered at various times during
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the past 12 years and have been turned down on account of unsatisfactory features; neither the Germans nor the Japanese have adopted them, though we must assume they have fully considered the problem. We think it would be unwise to alter radically our turret design before being sure that the advantages to be gained by the change make it worth while.
47. The chief points to be considered in respect to a three-gun turret are whether:-
(i) The third gun will enable a great rapidity of accurate fire to be obtained;
(ii) The present high rate of loading can be arranged for reach gun;
(iii) The turrets as a whole will be as simple and reliable as the present type.
(iv) With guns of 16-in. or larger calibre, ti would not be more economical of weight and space to mount five pair-gun turrets rather than four triple.As regards these:-
(i) Assuming that the time of loading is the same for all guns of a turret, director firing should ensure that a proportionately greater volume of fire is obtained from three guns than from two; it requires to be proved that accuracy will not suffer materially on account of the discharge of two or three guns mounted close together as would be necessary to take full advantage of the number of guns in the armament; trials are therefore necessary.
(ii) and (iii) are questions principally of design and until satisfactory designs have been produced there is little profit in offering opinion; probably, however, useful information of practical working of triple-gun turrets could be obtained from foreign navies. It is on threes three accounts that the Committee has pressed for trials to be carried out in the Russian battleship “General Alexieff.”
(iv) is a constructive question and we have been informed by the D.N.C. that it would be lighter to mount ten 16-in. guns in pairs than twelve as triples; but, to be able to give an authoritative opinion on the matter, the designs need working out fully so that it may be seen how they compare in the matter of space and protection.
48. Conclusion and Recommendation. – We are not prepared that new battleships should carry only four pair-gun turrets as against the U.S.A. four triple-gun turrets, the adverse preponderance would be altogether too great. Nor are we prepared to advise the acceptance of any margin against us if our number of guns per turret is the same as in foreign navies, i.e., if we adopt triple-gun turrets and 16-in. guns we should mount 12 guns in four turrets similar to the U.S.A. If the U.S.A. reverts to pair-gun turrets, we can be content to adhere to them.
If, however, trials should prove that the triple-gun turret is not satisfactory, then we consider that, provided our ships have the superiority in numbers of turrets, we can then allow a gun margin against us of not more than 12 to 10, i.e. a British fire pair-gun turret against a foreign four triple-gun turret ship.
Outfit of Ammunition
49. War experience not sufficient guide. – The war threw very little light on this question because, except at the Battle of Falkland Islands, no action between Capital Ships was fought to a finish. At the Falklands “Invincible” and “Inflexible” had little ammunition left when the action was over although they had filled up to maximum stowage before leaving England, “Inflexible” actually firing 661 rounds, 21 more than her pre-war outfit.
50. Causes affecting size of outfit. – The range of opening fire has much increased as the result of war experience and is now limited only by ability to spot. Development of aerial spotting may increase it further; director firing has greatly improved rapidity of fire.
Accuracy has progressed due to the director and to experience gained in firing at long ranges. It is not, however, sufficient by itself to obtain hits at long ranges, because the danger space of the target is so small.
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It follows therefore that if fire is opened at extreme ranges and continued at the normal rate, a large expenditure of ammunition must be expected before decisive results are obtained.
51. Increase during War. – Our ammunition outfits were increased during the war from 80 rounds per gun in all Capital Ships to 120 rounds per gun in battle cruisers and 100 rounds per gun in battleships, the extra 20 rounds in battle cruisers being carried because of the probability that these ships would have more frequent opportunities of engaging.
52. Recommendation. – Taking all circumstances into consideration, and especially the present tendency to increase the range of opening fire, we are of opinion that outfits ought to be increased and recommend 120 rounds per gun for battleships and 140 for battle cruisers.
SECONDARY ARMAMENT
53. Relative importance. – We consider that the secondary armament of a battleship must be subordinated to her essential characteristic, namely primary armament, protection, speed and size.
54. The conditions of warfare are constantly changing and developing with the introduction of new, or improvements in existing weapons. In greater or less degree these changes affect ships in almost every important particular, and consequently most of all in design. This point is mentioned here because of its bearing on the manner in which guns are mounted on board ships; every requirement cannot be me and secondary armament must to some extent be fitted in.
55. Functions of Secondary Armament. – The following include all the purposes for which the secondary armament may be employed. The order in which they are placed should not be taken as the order of importance because, the secondary armament being defensive, its object is to beat off whatever form of attack is delivered.
(i) To employ against aircraft of all descriptions which come within range, and especially against low-flying aircraft such as torpedo carrying planes.
(ii) To repel destroyer attack at night or in low visibility when time or circumstances do not permit of evading tactics.
(iii) To employ, in addition to the primary armament, against vessels of any description which may be engaged at night or in low visibility.
(iv) To repel destroyer attack during day action with other Capital Ships.
(v) To employ against light cruisers when their number is too great for the primary armament to deal with or when the latter is engaged with heavy enemy ships.
(vi) To repel attack by mosquito craft, such as coastal motor boats and distant control boats.
(vii) To employ against submarines.
(vii) For protection in harbour against any form of attack.
(ix) For firing shell required for special purposes, such as star and smoke shell.
Lastly, without including it amongst the functions of the secondary armament, may be added its moral value as a deterrent to all smaller vessels to take liberties.
Calibre of Gun.
56. Service opinion divided. – The evidence we have heard and seen shows that Service opinion is not agreed upon secondary armament questions, the chief point of difference lying in the calibre of gun to be mounted. This divergence of opinion is not new, for it existed before the war, and it is doubtless owing to the war having thrown insufficient light on the subject that opinions remain divided.
One school of though favours the heaviest gun capable of being loaded and manipulated as rapidly as our present 6-in., and the other a lighter gun having a very high rate of fire and a very easily manipulated mounting.
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Those in favour of the heavier gun, who are in a large majority, are of opinion that the necessary range will not be obtained with a gun of less that 5.5-in. calibre. Further, they consider that, in practice, the difference between the rate of controlled fire for guns varying form 6-in to 4-in. calibre is too small to be of consequence, thus leaving the advantage with the heavier gun in nearly all other respects.
Those who differ from the above and favour the smaller gun do so chiefly on the grounds that ti saves weight and space, thus permitting a larger number to be mounted, and that it has been proved by experience with the triple mounting that the lighter gun is capable of a considerably higher rate of fire than the 6-in., especially at high elevations. They do not attach the same importance to range and consider that the calibre of the secondary armament of battleships need not be influenced by the armament of light cruisers, and believe that a lighter, handier and faster-firing gun can be more effectively used against destroyers, mosquito and torpedo-carrying aircraft; the last may become on of the most serious menaces to the Capital Ship.
57. Recommendation. – We recommend that calibre of gun from which the best results are obtained firing a 100-lb. shell.
We consider that the 100-lb. shell has so amply demonstrated its effectiveness during the war that it would be unwise to discard it for one too heavy for hand loading, or for one which being materially lighter does not possess the same ballistic advantages. Both these points are dealt with more fully in the next paragraph.
We note that the conclusion drawn from recent loading trials in “Excellent” is that projectiles weighing 90 lb. are the heaviest which average men can handle quickly during sustained firing. We do not think, however, that this is in accord with war experience. Many years of experience at Gunlayer’s Test did not suggest a projectile lighter than 100 lb. for there was no difficulty in finding loaders who could work faster than the gun could be fired, and could do so quite easily. At present day mountings the breech of the gun is certainly higher than it used to be, because of the increased elevation allowed for, and therefore the effort to load is greater. But height can be reduced by different design of mounting, and loading may be made easier by the use of loading trays. If 100-lb. shell are the best for their purpose, they ought not to be given up to suit a particular design of gun-mounting or to satisfy exacting conditions of firing.
58. Effect of calibre and eight of shell upon rate of fire and ballistics: - Rapidity of fire is essential since the opportunity to fire may last only a short time and it is necessary to take full advantage of it. Experience has shown that light craft are not always stopped by a hit even from the heaviest shell; it is more important that blows should be frequent so that their effect is cumulative; rapid fire is more disconcerting to exposed personnel.
The maximum rate of fire from a battery of hand-loaded guns of medium calibre is dependent on, (i) the rate of ammunition supply, (ii) the time required for loading, and (iii) the efficiency of the control. In a big ship, which is usually a very steady platform and where there is ample room for the ammunition hoists and loading operations, (i) and (ii) will not differ very materially for medium calibre guns provided that the arrangements are good and the ammunition is not too heavy for quick handling; (iii) is altogether independent of the calibre of the gun and depends on the director layer and control officer.
In practice, the maximum rate of fire from a 6-in. (100-lb. shell) battery is, at best, eight salvos per minute; six is as many as it is safe to count upon. From a batter of 4-in. (31-lb. shell) twelve salvos per minute is possible, eight are easily obtained. The 5.5-in. gun (80-lb. shell) is a little quicker than the 6-in., but slower than the 4-in.
Long Range is necessary to meet the attack of modern weapons; the war proved that guns can be effective up to the extreme range at which their shot can be spotted. A range of 20,000 yds. is recommended. Advantage lies with the larger calibre gun and its heavier shell; in fact, unless very large angles of elevation are allowed on the mounting, guns of less than 5.5-in calibre will not give sufficient range.
Danger Space. – The importance of danger space has already been alluded to under Main Armament (see para. 24). With the secondary armament, which has to deal with fast moving targets, hitting is, if anything, more dependent on size of danger space. The heavier gun has a good deal the best of it especially as range lengthens.
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Accuracy. – Accuracy is less important for secondary than for main armament guns because range is often short and then danger space counts for more than accuracy. The point is that, although accuracy is desirable, ti should not be pressed to the disadvantage of danger space. Another reason is that inaccuracies of control are in any case likely to be so large that the accuracy of the individual gun is not of first importance. The probability is that the heavier the gun the better the accuracy.
Burst Effect should be as large as practicable to obtain decisive results. In this respect the gun firing the heavier shell must be superior.
Armour-piercing Qualities. – These may or may not be necessary for secondary armament shell as high capacity shell have greater effect on unprotected ships. The heavier gun, however, again ha the advantage.
59. Opinion. – We consider that a rate of fire of six salvos per minute is sufficient and, this being so, that the great advantages of range, facility in spotting and danger space of the heavier gun and the greater burst effect of its shell far outweigh the greater rapidity of the smaller calibre.
60. Reason for not recommending Exact Calibre. – At present, guns of medium calibre (6-in. to 4-in.) are not using shell of the f