A Cruiser Program

Before the Washington treaty, the design of cruisers was influenced by the needs of the individual nations and the “styles” prevailing at the time, but it was limited only by financial considerations. Theoretically (assuming superhuman intelligence, including the ability to forecast naval needs) it was possible to design one or more “ideal” types and then build as many of each type as required for its specific purpose.

The Washington treaty first imposed limitations on cruiser design by fixing the maximum standard displacement at 10,000 tons and the maximum caliber of gun at eight inches. The London treaty provided two more limitations. First, it limited the gun caliber of a certain portion of our cruiser tonnage to six inches. Secondly, it established total tonnage limits on each of the subcategories of cruisers—the 8-inch and the 6-inch. This latter limitation— that of total tonnage in a given class— makes it necessary to consider not only what the “ideal type” for a given duty is, but how many of that type we should build without encroaching on the tonnage requirements of other types. This question is all the more important because the London treaty, in two or three cases, permits a certain amount of flexibility; and it becomes necessary to determine the most advantageous course to follow in each of these cases. For example, one of the flexible provisions is that which permits us to build “flight-deck” cruisers up to a total of 25 per cent of the total cruiser tonnage, i.e., about 80,900 tons. We must decide not only the optimum characteristics for such a ship, but also how many we should build.

This whole question of types and numbers is an exceedingly difficult problem, and is one on which a great many varying opinions will be found. This paper is not presented as a perfect solution to a knotty problem; it merely represents the personal convictions of one writer. Nevertheless, it is hoped that it will stimulate discussion. We all trust that careful consideration of the question now will lead to the adoption of a definite cruiser program which will ultimately give us the maximum value for our allotment of cruiser tonnage.

In attacking this problem it is convenient, first, to analyze the courses open to the United States under the London treaty; then to decide upon the characteristics of the types most needed by the Navy; and finally, to prepare a program which gives us adequate numbers of each type.

In this analysis we need consider only those ships which can be laid down up to December 31, 1936, the expiration date of the London treaty. The basic tonnage limits set by this treaty are for 8-inch cruisers, 180,000 tons; for 6-inch cruisers, 143,500 tons.

Under this treaty the following courses are open to the United States:

Course I. Build up to a total of eighteen 10,000-ton, 8-inch cruisers, using the remaining tonnage for “straight” 6-inch cruisers (as opposed to “flight-deck” cruisers).

Course II. Build up to a total of fifteen 10,000-ton, 8-inch cruisers, using the remaining tonnage for “straight” 6-inch cruisers, with the provision that the 30,000 tons of 8-inch cruisers not built may be exchanged for 45,498 tons of 6-inch cruisers.

Under either Course I or Course II “flight-deck” cruisers may be built instead of “straight” 6-inch cruisers, to a total of about 80,900 tons. For convenience in discussion these will be treated as two separate courses, defined as follows:

Course III. Same as Course I, with the substitution of a certain number of “flight- deck” cruisers for “straight” 6-inch cruisers.

Course IV. Same as Course II with the substitution of a certain number of “flight- deck” cruisers for “straight” 6-inch cruisers.

	Course I		Course II		Course III			Course IV
	a	b	a	b	a	b	c	a	b	c	d
8-inch cruisers..........	18	18	15	15	18	18	18	15	15	15	15
6-inch 7,200-ton.......	12	—	18	—	—	9	—	7	—	15	—
6-inch 10,000-ton.....	—	8	—	13	—	—	6	—	5	—	11
6-inch flight-deck cruisers	—	—	—	—	8	2	2	8	8	2	2
Omahas....................	8	8	8	8	8	8	8	8	8	8	8
Total units................	38	34	41	36	34	37	34	38	36	40	36
Surplus tonnage........	700	7,100	2,998	2,598	7,100	2,300	7,100	2,198	2,598	4,598	2,598

The treaty permits a transfer of destroyer tonnage to 6-inch cruiser tonnage to the extent of 10 per cent of the 6-inch cruiser tonnage, that is 14,350 tons. This might be highly desirable, but may be disregarded here as the option may be exercised under any one of the aforementioned courses.

We have built and operating ten cruisers of the Omaha class, two of which may be replaced by ships to be laid down prior to December 31, 1936. Thus we have eight Omahas of a total standard displacement of 56,400 tons. There remains a total of 143,500 minus 56,400, or 87,100 tons to devote to new 6-inch cruisers under Course I, or 132,598 tons under Course II.

The question of size enters the problem. For reasons to be discussed later, 7,200 tons is taken as the minimum size. The maximum, by the terms of the treaty, is 10,000 tons. For simplicity only two sizes, 7,200 and 10,000 tons are considered.

We are permitted to build 80,900 tons of “flight-deck” cruisers. In order to secure all the necessary features such ships will require the full 10,000 tons allowed. We may build eight units of this type as a maximum and, for reasons to be stated later, we may set a minimum of two units.

The following table shows our total cruiser force possible under the various courses open to us, with subcourses providing for the choice of the 7,200- or the 10,000-ton, 6-inch cruiser.

The figures for surplus tonnage are given to show how nearly each subcourse uses up the total allowed tonnage. This tonnage does not need to be wasted. In the subcourses where 7,200-ton ships are considered, the surplus could be spread over these ships to make each a little larger, but still in the same general class as far as military characteristics are concerned. It must be remembered that additional tonnage cannot be added directly to useful weight, such as armament or protection. If, for example, 300 tons be added to the displacement, only from 125 to 150 tons can be added as useful weight. The remainder goes into hull weight to support the added useful weight. In the three cases where 7,100 tons remain as a surplus this would probably be used for an additional vessel, either a “straight” 6-inch cruiser, or some special type for a particular service. The surplus of 2,598 tons remaining in three cases might also be used in some such manner, but the need for a special ship of this size would be considerably less. In any case, in the discussion which follows the general considerations involved are considered to outweigh any consideration of the distribution of surplus tonnage.

Characteristics of types.-—One of the first questions which confronts us, in looking over the courses open to us, is whether we should include “flight-deck” cruisers in our program. This type has been roundly criticized, and staunchly supported. An entire paper could well be devoted to a discussion of the advantages and disadvantages of this so-called “hybrid,” but the subject must be treated very briefly here. It is merely intended to point out a few facts which are considered to justify the inclusion of such a type in our cruiser program.

In the first place, to fall within the limits of the treaty, such a ship must be primarily a cruiser—she must have cruiser speed, cruiser protection, and above all cruiser battery. It may not be the maximum cruiser battery, but it must be a good substantial battery for a cruiser of its size. This statement is meant to include the anti-aircraft battery, which should be similar to that installed on the best modern cruisers. So much for the cruiser features. Now if we endow such a ship with a flight deck and a good complement of planes we have a powerful cruiser with “long arms” and greatly extended vision. We hear it argued that in bad weather she would be unable to use her planes. This is granted, but in such weather she is still essentially a cruiser. In good weather she has the tremendous advantage of long range of vision and additional striking power. Success in battle often lies in being able to take advantage of a favorable opportunity. The advantage of a large number of planes to a cruiser engaged in locating enemy commerce raiders, in patrolling commerce lanes, or in strategical scouting can hardly be overestimated. She has the advantage over cruisers with catapults in being able to keep a continuous patrol of planes in the air and in the ability to land planes without stopping and operate them in weather when seaplanes could not come alongside to be picked up. The only other way that these advantages can be obtained is by sending an airplane carrier with each cruiser, and this would obviously necessitate more carriers than we are permitted under the treaty.

For excellent discussions of the possible uses of flight-deck cruisers the reader is referred to an article by Lieutenant Commander Sherman in the November, 1930, issue and a discussion by Commander Turner in the May, 1931, issue of the Naval Institute Proceedings.

Another point to consider in connection with flight-deck cruisers is that possible developments in aeronautics may permit the use of a smaller flight deck than is now contemplated, thus giving improved cruiser characteristics with the same aviation facilities. Consider the advantages which might accrue to such a ship if the autogiro were found to be practicable for naval uses.

However, all these advantages cannot be had for nothing. There must be a sacrifice in one or more of the cruiser characteristics. Furthermore, it must be recognized that this is a new type, never actually built and tested in service. It would be rather a bold prophecy to state at this time that the advantages will greatly outweigh the disadvantages. But the converse is equally true. The type gives great promise of being a valuable adjunct to the fleet, and the possible advantages are considered so important that we should not be satisfied until it has been built and thoroughly tested. Service tests of any type invariably lead to improvement. Service tests of this type may lead to such improvement as to dispel all doubt as to its value. For this service test, it is considered advisable to include only two of these ships in our present program. Two are specified because with two ships we can make parallel installations of two types of gear—elevators—for example, and determine the better from actual service. We can also obtain service reports from two sets of personnel operating under different conditions and accelerate the test. Having built two such ships, the end of 1936 would be about as soon as we could hope to have conclusive reports on their performance. Further ships of this type would then be laid down in 1937, and would fall outside the limits of the present discussion.

With two flight-deck cruisers established in our program we have narrowed the problem down to a consideration of the courses shown in the tabulation as Course III (b) and (c), and Course IV (c) and (d). That is to say, we now have to choose between eighteen 8-inch-gun cruisers with six to nine new 6-inch cruisers, or fifteen 8-inch-gun cruisers with eleven to fifteen 6-inch cruisers. This problem, of course, opens up the whole question of cruiser duties and the best type for each duty.

As a motto for an article entitled “The Cruiser Problem” in the Naval Institute Proceedings for May, 1930, Lieutenant Percival chose the following quotation from Mahan: “In the designing of a cruiser as of any class of warship, the first step before which none should be taken is to decide the primary object to be realized—- what is the ship meant to do?” This is indeed an admirable principle and none of us could question it. Yet how many cruisers have been designed with a label attached “This ship is intended to perform solely, or even primarily, such and such duties.” The cruiser, by its very nature, is a “Jack- of-all-trades”—the diversity of its uses is only exceeded by the diversity of opinions regarding its characteristics for those uses.

A study of articles appearing in the Naval Institute Proceedings during the past ten years reveals some very interesting things; first, the wide diversity of opinion on cruiser design, and, second, the fact that very few writers attempt to prescribe definite types for definite cruiser functions.

A brief review of the conclusions of some of these writers should be worth while.

In an article entitled “The Cruiser” in the issue of April, 1926, Lieutenant Webster lists cruiser duties as follows (omitting certain very special duties such as mine laying):

(a) The destruction of enemy commerce
(b) The protection of commerce
(c) Showing the flag (peace time)
(d) Dispatch and communication service and patrol duties of various kinds
(e) Raids—bombardment of enemy coasts etc.
(f) Blockade
(g) Scouting for a fleet
(h) Beating off enemy destroyers
(i) Supporting our own destroyers
(j) Torpedo attack (which should be no logical function of a cruiser)

Without attempting to specify the type of ship to be assigned to any given duty Lieutenant Webster summarized his conclusions as follows:

The vital requirements of any cruiser are seaworthiness, speed, radius, cheapness, which represents numbers, and hitting power.

These requirements would seem to be best met by building cruisers of two types:

(a) Numerous ships—as small as consistent with the above
(b)  A number of cruisers that are as powerful as may be built

In an article entitled “Cruiser Types” in the issue for March, 1927, Lieutenant Percival arrived at three distinct types, as follows:

(1) The destroyer scout, similar to the destroyer leader, but of about 3,000-ton displacement

Proposed duties:

(a) Scouting
(b) Torpedo attacks, counterattacks
(c) For conversion to carry coastal motor boats or mines
(d) Raiding convoys or communication lines
(e) Gunboat duty
(f)  Escorting light mine layers or motor boats
(g) Destroyer leader duty

(2) The armored cruiser; 10,000 tons; 8- inch guns; ample protection against 8-inch; 25 knots speed.

Proposed duties:

(a) Fleet screening
(b) Support to destroyers and scout cruisers
(c) Ocean escort
(d) Fleet flagship
(e) Towing damaged vessels
(f)  Protecting aircraft carriers

(3) The scout cruiser; large, fast, heavily armed but scantily protected.

Duties:

(a) Scouting
(b) Commerce protection
(c) Escorting light mine layers or motor boat carries
(d) Screening aircraft carriers
(e) Raids in force on lines of communication

The same author in an article entitled “The Cruiser Problem” in the issue for May, 1930, proposed the following types:

(1) The battle cruiser type; 10,000 tons; six 8-inch guns, nine 5-inch guns; 28-30 knots speed and reasonable protection against the 8-inch gun.

Duties:

(a) Scouting
(b) Supporting or breaking up destroyer attacks
(c) Raiding
(d) Hunting

(2) The battleship type; 10,000 tons, ample protection against 8-inch shells, nine to twelve 8-inch guns, 21-25 knots.

Duties:

(a) Protecting convoys
(b) Screening the fleet at night or in thick weather
(c) Protecting aircraft carriers during an action
(d) Breaking up destroyer attacks

(3) The aircraft carrier type; which is actually a 10,000- ton carrier, and not permitted to be built out of cruiser tonnage under the London treaty.

(4) The destroyer type; primarily torpedo craft of small displacement.

(5) The submarine type; actually submarine cruisers, and hence not pertinent to the present discussion.

There have been many other articles and discussions on general cruiser characteristics—too many to review even briefly. One discussion, however, is quite pertinent to the present article. In discussing Lieutenant Percival’s first article, Captain H. C. Dinger says: “ Is it better to have half a dozen different types, as the author seems to think, or one type that, after due consideration, appears best to meet cruiser needs? I think the answer is, one type, unless we are to build more than twenty.”

In an article entitled "Light Cruisers" in the issue for September, 1926, Captain Howard reaches the same conclusion. He divides cruiser duties into two general parts: “operations with or in connection with the fleet, and independent operations.” After a complete and searching analysis including a thorough review of independent cruiser operations during the World War he states his conclusions as follows: “The studies carried along quite separately for two types have brought exactly the same conclusion in each case. A light cruiser in whatever r61e she is placed must be a fighting vessel.” And later, “Finally then, whatever the work in hand may be the cruiser must be first and last a fighting ship, possessed of the best all- around fighting qualities possible to obtain on the displacement of 10,000 tons.”

We may argue for a single type of cruiser without contending that it is impossible to prescribe certain types for certain duties. Indeed it must be conceded that a careful analysis might yield a very definite “ideal” type for each duty, from a theoretical standpoint. Furthermore, a commander in chief might be very glad to push a button and have the ideal type for his immediate need appear at the psychological moment. But naval warfare is not conducted that way, and we must provide the best average type for the best average duty. Captain Howard expressed this point very strongly when he said “Even if two types were needed, no country . . . is rich enough to build double the number of warships actually needed, simply to have two types to meet two conditions. Even if such were done the vessels of the type wanted would undoubtedly be in one place just when the other type was wanted there.”

It is proposed, then, that our present problem is not one of designing “ideal” types to perform theoretical duties; but the very definite practical problem of allotting our remaining cruiser tonnage to secure the maximum fighting value under average cruiser conditions. This means getting the best combination of numbers of ships, numbers of guns, and “fighting strength” of individual units. The “fighting strength” of a unit depends on the number and size of guns, volume of fire, protection, speed, radius, and to a certain extent maneuverability.

Let us consider first the 6-inch cruisers. Early in the article 7,200 tons was set as the lower limit. It is doubtful if all the military characteristics we would want, even for a small cruiser, could be attained on much less than this. Even if we set out to design a 6,000- or 6,500-ton cruiser it is probable that the pressure would be so strong for increased armament or protection, or habitability, or all of these, that the displacement would increase materially before the ship was finally designed and constructed. Hence the lower limit of 7,200 tons was set as a basis for discussion. The upper limit is set by the treaty at 10,000 tons. The speed of the two types is assumed to be the same, as there is a remarkable tendency for all nations to approach a standard cruiser speed of about 32 knots.

A complete comparison of the fighting strength of an equal tonnage of these two types can only be had, in the last analysis, by opposing one group against the other in actual battle. It is the old, old question of a large number of small ships against a smaller number of large ships; and any solution may well be open to the criticism that it is “theoretical,” and even “fallacious,” especially if the critic happens to be of the opposite school of thought. Nevertheless a comparison of the elements of fighting strength appears to be the best means at hand of deciding the question.

In the first place, a fact not generally recognized is that on a 10,000-ton cruiser there is available for battery, ammunition, and protection some 4 per cent to 5 per cent more displacement than on a 7,200- ton ship of the same speed. Thus, if we take ten of the small ships and seven of the large ships (approximately equal tonnage) we have 4 per cent of 70,000 or 2,800 more tons to devote to protection, battery, and ammunition in the large ships than in the small ships. In addition it works out that the cruising radius of large ships will be somewhat greater than that of small ships.

The first element of fighting strength listed was number and size of guns. Since we are discussing only the 6-inch cruisers at present, we need only compare the numbers. On the 10,000-ton ship we would probably not mount more than four triple turrets, if for no other reason than space considerations. On the 7,200-ton ship we may reasonably assume nine guns. For the example given above this gives a total of eighty-four guns on the large ships and ninety on the small ships.

The second item listed is volume of fire, which, since the gun size is the same, is in direct ratio to the number of guns.

The third item is protection. As they have greater capacity for carrying military load the larger ships can be well protected against the 8-inch gun whereas the small ships can only be protected against the 6-inch gun.

The fourth item, speed, has been assumed the same in both cases.

The fifth item, radius, is definitely greater in the larger ship.

The last item, maneuverability, is generally accepted to be better in smaller ships. But it must be remembered that the difference in length between a 7,200-ton ship and a 10,000-ton ship is not great, so the difference is not great.

The above comparison is not needed to prove that a 10,000-ton cruiser is a better fighter than a 7,200-ton cruiser—that should be obvious. But it does give us a basis for comparing groups of equal tonnages of these types. Taking the example given of 72,000 tons of small cruisers compared with 70,000 tons of large cruisers we have the following table:

	7,200-ton	10,000-ton
	units	units
Number of units	10	7
Number of guns	90	84
Volume of fire	90	84
Protection	against 6"	against 8"
Speed	equal	—
Radius	—	superior
Maneuverability	slightly superior	—

Thus we find on all counts but protection and radius that the smaller ships have a slight superiority. The matter of number of units is a very real advantage, especially for employment on independent duty. But we must remember that going too far in this direction leads to the policy of the Jeune Ecole, long since abandoned in France. Would our choice of 7,200-ton cruisers be going too far? Could we afford to purchase three or four more units at the price of inadequate protection for all units?

One of the best papers recently published on the matter of protection is that by Professor Hovgaard entitled “The Relation between Armament and Protection in the 10,000-ton Cruisers and the Ersatz Preussen,” reprinted in the Naval Institute Proceedings for December, 1929. His discussion of this subject is strongly recommended to all who are interested in the theory of protection, particularly to those who are inclined to minimize its value. Especially valuable are his quotations from Jellicoe’s The Grand Fleet. Professor Hovgaard’s statement of the “principle of corresponding protection,” which is well substantiated by experience as well as logic, is as follows: “An artillery ship should be so protected that it can keep up a sustained fight under average conditions with a ship of similar size and type and carrying the same armament.” In developing this principle, however, he states, “In order to arrive at a rational design of the protection it is necessary to make assumptions as to the adversary which the ship is destined to fight, in particular as to the caliber of his guns.”

It is here contended that in the particular case of the 6-inch cruisers this principle of corresponding protection should be interpreted to provide protection against the 8-inch gun. It must be remembered that at present the 8-inch cruisers in the navies of the four treaty powers (excluding the United States) number about 40 per cent of the total. This does not necessarily mean that the 6-inch cruiser has a 40 per cent chance of meeting an 8-inch cruiser; it does mean that such chance is appreciable. It may not be entirely within our power to pit 6-inch cruisers against 6-inch cruisers and 8-inch ships against 8-inch ships, especially on independent missions. Now a 6-inch cruiser with inadequate protection can scarcely be credited with any chance of survival against an 8-inch cruiser, whereas, with adequate protection against the 8-inch gun, this ship may, by superior skill, have a fair chance of disabling the enemy and of coming out of the engagement with enough ship left to accomplish its mission. Another point must be emphasized in this connection. In providing protection for a chance encounter with the 8- inch ship we also provide an increased margin of safety against the 6-inch ship. Light cruiser protection, at best, can only be effective within certain rather narrow “zones of immunity” and all we can do to widen those zones will give just so much more liberty of action to ship and force commanders in time of battle.

Other arguments might be advanced for the larger size. Professor Hovgaard, in his General Design of Warships states as part of his conclusion to the chapter on “ Size of Warships”—“The foregoing discussion shows that larger ships, quite apart from their greater carrying capacity, possess inherent nautical, technical, military, and economic advantages, which render them intrinsically superior to smaller.” But, for the case in hand, it is considered that the question of protection alone is sufficiently important to be the determining factor.

With 10,000 tons set as the optimum size for 6-inch cruisers we now have to choose between eighteen 8-inch cruisers with six 6-inch, and fifteen 8-inch cruisers with eleven 6-inch. Here indeed is a much more perplexing problem. Based on the foregoing reasoning we should naturally expect the decision to lie with the 8-inch ship, as representing the more powerful battery. But here we have a special clause in the treaty to consider. By building the 6-inch cruisers we are allowed approximately 15,000 more tons than by building the 8-inch cruisers. Referring to the original tabulation of units under Course III (c) our new construction would consist of three 8-inch cruisers; six 6-inch, 10,000-ton cruisers; two flight-deck cruisers; and 7,100 tons of surplus tonnage, which we may here evaluate as approximately three- quarters of a 6-inch cruiser. Under Course IV (d) the new construction would consist of no 8-inch cruisers; eleven 6-inch, 10,000-ton cruisers; two flight-deck cruisers; and only 2,598 tons of surplus tonnage, which we may neglect. The difference between the two courses, then, is three 8-inch cruisers in favor of Course III (c) and four and one-quarter 6-inch cruisers in favor of Course IV (d). (The actual difference in 6-inch, 10,000-ton cruisers is five in favor of Course IV (d), but to allow for the existence of greater surplus tonnage under Course III (c) we may call this figure four and one-quarter.) In comparing these 8- and 6-inch cruisers, ship for ship, we must remember that they have approximately the same protection, same radius, same speed—in short, are the same in all respects except battery. The latest 8-inch ships have a battery of nine guns, and the 6-inch cruisers are assumed to have a battery of twelve guns. The actual weight of metal thrown per salvo is more for the 8- inch-gun ships; the penetrative effect of the 8-inch shell is greater against vertical armor and slightly greater against horizontal armor; the 8-inch gun has the advantage of range. However, the 6-inch gun has greater rapidity of fire, which in many cases may be a great asset. It also has a greater number of guns per ship, which makes for greater accuracy of fire, at least for one group of guns, in case of divided fire. If some of the foreign cruisers are as lightly protected as they are reported to be, the 6-inch cruiser would undoubtedly be very dangerous to them.

Proponents of the 8-inch cruiser may well, on the basis of the comparison set forth above, claim superiority for a single 8-inch ship against a single 6-inch ship, under certain conditions. But since the 6-inch is well protected against the 8-inch gun she would have quite a fair chance against the 8-inch ship under certain methods of conducting the fight. Certainly the difference is not nearly so appreciable as that in the comparison previously made between large 6-inch and small 6-inch cruisers. Now when we come to compare not equal tonnages of these ships, but unequal tonnages as allowed by the treaty, it would seem to be to our advantage to take the eleven 6-inch, 10,000-ton ships, in preference to three 8-inch ships plus six 6-inch (plus one “extra number” of 7,100 tons). In this way we utilize our allowed tonnage, almost to the last ton, in powerful, homogeneous fighting units.

The program finally proposed then is as follows:

		New Construction
8-inch, 10,000-ton cruisers	15	—
6-inch, 10,000-ton cruisers	11	11
6-inch, flight-deck cruisers	2	2
Omahas	8	—
Total units	36	13

This compares with a maximum possible number of practical units (7,200 tons and above) of forty-one and has the advantage of being composed of powerful, well protected “ straight” cruisers, plus two flight- deck cruisers which give promise of having great strategic value.