Us navy Interwar Cruiser Design and Development

By

HH386

28 February 2005

During the years between World War I and World War II, the cruiser evolved from something resembling a minor battleship to a type similar to a minor battle cruiser. After expending huge amounts of money on the naval arms race that preceded World War I, the great powers of the world agreed to limit the size and composition of their navies by the Washington Treaty of 1922. In order to prevent the transformation of cruisers into battleships, the treaty limited the type to a displacement of 10,000 tons and guns no larger than 8 inch. However, combining heavy armor, high speed, and large guns was impossible to do on the 10,000 ton limit. Thus, American naval architects in the 1920’s and 1930’s were forced to make sacrifices in protection to maintain the speed and armament required. Historians have since labeled the resulting ship type the “Treaty Cruiser.”

Even before the interwar period, cruisers played a vital role in American naval policy. Cruisers were a key component of the new Navy from the outset of American naval reconstruction. Starting in 1883, the United States Congress authorized three cruisers that formed the core of the “Squadron of Evolution,” demonstrating America’s renewed commitment to naval power. The US Navy envisioned the cruiser as a multi-purpose ship and over the course of the next several decades the cruiser evolved slowly and its missions changed little. One of the principal tasks cruisers were intended to perform was to be the fast scouting arm of the fleet. Before the advent of aircraft and wireless telegraphy, cruisers performed the hazardous but necessary duty of locating the enemy fleet, discerning its composition, and returning that intelligence to one’s own fleet by steaming back to it at full speed and relaying the information visually. This was tactical scouting, and it was crucial to the outcome of a naval battle at that time. Cruisers also to be performed strategic scouting which could determine not only the course of a battle, but the outcome of a war. Strategic scouting, also described as distant scouting, involved roughly fixing the location of an enemy fleet as it left port or arrived in a war zone.¹

Secondary to the scouting role was that of chasing down enemy commerce raiders. American naval officers, informed by the disaster wrought by Confederate raiders on Union shipping during the Civil War, were consistently concerned about preventing a repeat occurrence in another general naval war. The logic was that if the enemy were to use a fast and well-armed ship to sink merchant vessels, then an equally fast and well-armed ship would be needed to counter it. Finally, the cruiser had to be able to perform what was referred to as “peace time cruising,” where by the cruiser would travel to distant ports of call and show the flag of its nation, demonstrating that government’s concern with the area as well as its power.²

In the late 19^th century and early 20^th century technical limitations made building one ship that could perform all of these missions impossible. For example, early steam propulsion was limited to reciprocating engines that were inefficient, bulky, and allowed for maximum speeds of only 20 to 24 knots. If engines large enough to reach high speeds were fitted to a ship, armor and armament necessarily had to be sacrificed. Thus, the many missions assigned to cruisers led to several distinct types of cruiser in the US Navy by the outbreak of World War I in 1914. Scout cruisers were built with light armor and armament, but with the highest speed possible. Armored cruisers, on the other hand, were built with heavier armament and armor sufficient enough to withstand a hit from their own battery. In this sense, armored cruisers became minor battleships and served as such. The protected cruiser was a third type that was something of a compromise. It sacrificed some armor to gain speed over an armored cruiser and was better armed than a scout cruiser. However, it was still slower than the scout cruiser and the type came to be regarded as terribly vulnerable.

The aftermath of the First World War markedly changed this division of cruiser designs. Technological innovations such as the submarine, aircraft, long range torpedoes and gunnery, and steam turbines coupled with reduction gearing impacted the supposed role of the cruiser greatly. Additionally, the end of World War I left the balance of naval power forever changed. Germany’s defeat and the subsequent scuttling of the High Seas Fleet in Scappa Flow ended her reign as a competitive naval power. The US Navy was pushing hard for equality with the British Royal Navy. Japan, having taken over German territorial possessions in the Pacific and increasingly seeing both Great Britain and the United States as rivals, had renewed motivation for increasing the size of its fleet. Thus, in the years immediately following the Armistice in 1918, the world’s powers appeared to be locked into another naval arms race.

However, the Washington Naval Conference of 1922 diffused this situation. The resulting treaty signed by the five powers of the United States, Britain, Japan, France, and Italy limited naval construction through limitations on tonnage and other characteristics. Battleships, being the main symbol of naval power and the most expensive ship type, were regulated heavily with an imposed 10 year hiatus in new construction and a gross tonnage limit. Cruisers were somewhat less closely limited, since there was no total tonnage limitation. However, individual ships were still limited to 10,000 tons maximum displacement and guns no larger than 8 inches.³ It was under these treaty limitations and the technological advanced mentioned previously that the US Navy thus began developing the first of what came to be known as Treaty Cruisers.

American design work on the first ships to conform to the 10,000 ton limit actually began before the Washington Naval conference was concluded. In hearings conducted before the General Board of the Navy in 1920, the characteristics of a new class of scout cruisers were debated. The design was to be armed with “not less than 6 – 8” guns on the center line.”⁴ This ship was also to be equipped with oil-fired boilers to enable “smokeless steaming,” and have a “full speed of not less than 35 knots.”⁵ However, to attain these features the ship was to carry belt armor only 3 inches thick, and deck armor that was only 2 ¼ inches thick.⁶ In addition to these features, the General Board dictated these new scout cruisers be fitted to carry aircraft and torpedoes, as well as “be fitted as flag ships.”⁷ These particular aspects of this design speak of the growing importance of aviation to a cruiser’s scouting duties, as well as the view that flag ship duty fitted cruisers because they were large and fast ships. One final note of interest from these 1920 debates is the use of the term “light cruiser” in conjunction with the design. In fact, a member of the Board named Admiral Winterhalter described the design for the new scout cruiser as “Our conception of light cruisers.”⁸

The cruiser contemplated by the Board in 1920 was not built in 1921 as planned. However, the design became the basis for the first ships to be built under the restrictions of the Washington Treaty. In 1923, The General Board once again debated the characteristics for the new class of what were now firmly referred to as light cruisers. For this debate the Bureau of Construction and repair developed six different proposed designs for the board to consider, lettered “A” through “F.” Scheme “A” closely matched the design from 1920, and featured a high speed of 34 knots with only minimal protection around the ammunition magazines.⁹ Scheme “F” possessed significant protection, including a 8 inch armor belt, but developed a speed of only 27.5 knots.¹⁰ Thus, schemes “A” and “F” represented the different extremes of the armor versus speed debate. Schemes “B,” “C,” “D,” and “E” featured various steps down in either gun power or speed in order to gain armor.¹¹

In the ensuing debate, scheme “A” emerged as the favored option for a majority of the officers present. Interestingly, scheme “F” is scarcely mentioned. Several members supported schemes “D” and “E,” but it would seem that the speed sacrificed by scheme “F” was considered unacceptable by the members.¹² The reasoning Board members used in the debate is enlightening as to the proposed uses and missions of the planned ships. These ships were still intended for the purposes discussed by the Board in 1920. However, additional tasks were also proposed. A Board member named Captain Tompkins argued that based on his experience with war games at the Naval War College, light cruisers would be essential to repelling destroyer attacks on the battleship fleet. Since destroyers of the time were capable of speeds in excess of 33 knots, Tompkins argued “we should at least have that speed for the cruisers.”¹³ Destroyers were clearly viewed as the greatest threat to the light cruiser, principally because of the former type’s high speed. Thus, the light cruiser design needed protection from the guns of enemy destroyers. In essence, the General Board decided that light cruiser design should follow a philosophy similar to that of the battle cruiser, which is to have “Speed enough to get away from superior ships in armor and armament, and protection enough to get away from destroyers.”¹⁴ Another officer explained his support for the scantily protected scheme “A” by pointing out that the protection to be gained by sacrificing some speed would amount to very little. Thus, he argued, it would be better to forego protection and get all the speed that could possibly be had.¹⁵

The General Board also envisioned these new cruisers as carrier killers. Even in the early 1920s, the Board recognized that aircraft carriers would be vital asset in future naval operations.¹⁶ These light cruisers were seen as offensive units that could wrest control of an area from the enemy fleet by attacking the enemy’s carriers. The Board then reasoned that other navies must also be planning to attack American carriers in much the same fashion.¹⁷ Thus, the Board required the new cruiser design to be able to successfully engage not only the enemy surface screen, but the enemy’s carriers as well. This necessitated that the new light cruisers be armed with as many 8 inch guns as possible, since carriers with heavy gun armaments existed or were building in foreign navies at the time.

The General Board decided on this armament in the face of debates it conducted in 1921 as to the relative merits of the 6 inch gun versus the 8 inch. The Board classified 6 inch guns as rapid firing, which meant that they could get off several shots per minute. In contrast, the Board referred to 8 inch guns as quick firing, meaning they were capable of one or perhaps two shots per minute.¹⁸ The fact that 6 inch ammunition could be handled by a person while 8 inch shells and powder required mechanical handling accounted for the 6 inch gun’s higher rate of fire. While the 8 inch gun theoretically had a longer range, the gun laying equipment of the time negated that advantage to a considerable extent. At the 1921 debate, Board member Admiral McVay championed the idea of 6 inch gun cruisers pointing out that a 6 inch gun could fire 4 shots to every one round fired by an 8 inch gun. At the same meeting, another officer named Commander Rowcliff described the 8 inch gun as “A sort of mongrel type; it is not heavy enough to be effective against an armored ship, and has not been light enough to get much rapidity of fire.”¹⁹ The General Board nevertheless accepted these shortcomings and armed the first treaty cruisers with 8 inch guns.

By 1925, the Board completed the design that would serve as the basis for the treaty cruisers. The first two ships were commissioned in 1930 and 1929, and were named Pensacola (CA 24) and Salt Lake City (CA 25), respectively. The fact that these ships were armed with 8 inch guns meant that under the 1930 London treaty they were reclassified as heavy cruisers instead of light cruisers. Pensacola and Salt Lake City were armed with ten 8 inch guns arranged in two triple turrets super-firing over two twin turrets fore and aft. This unique design was necessitated by the limited hull volume in the area where the lower turrets were located, which prevented the instillation of the wider triple turrets in that location.²⁰ Another concern was that by locating the triple turrets in elevated positions, a greater portion of the battery would be drier in a seaway.²¹ However, this design choice contributed to an excessive metacentric height in these ships, which caused them to roll badly. Thus, the next batch of ships commissioned between 1930 and 1931 included Northampton (CA 26), Chester (CA 27), Louisville (CA28), Chicago (CA 29), Houston (CA 30), and Augusta (CA31) featured only nine 8 inch guns in three triple turrets with two forward and one aft. Otherwise, this second group closely followed the minimal armoring practices of the first two ships.

The next group of ships ordered by the Navy was CAs 32-36, and they were designed as slightly lengthened versions of the Northampton class. However, before their construction began the Bureau of Construction and Repair concluded that the Northampton class the third group was to be based on would be as much as 1,000 tons under the 10,000 ton weight limit when completed. The Bureau saved more weight than expected in the Northampton class by the use of aluminum fittings and electric welding in their construction.²² Furthermore, the weight calculations made by the designers turned out to be overly pessimistic in some cases.²³ As a result of this unexpected weight savings, Construction and Repair decided to redesign this third group to include increased ammunition stowage and armor protection in order to take full advantage of the 10,000 tons allowed by the treaty limit.²⁴ However, the Navy awarded the contracts for Portland (CA 33) and Indianapolis (CA 35) to civilian yards, and the penalties that would have resulted from changing the design so drastically were deemed unacceptable.²⁵ Thus, these two ships followed a design based on the Northampton class as originally planned and this group was divided into two classes.

The rest of the ships were built to a new design and included New Orleans (CA 32), Astoria (CA 34), Minneapolis (CA 36), Tuscaloosa (CA 37), San Francisco (CA 38), Quincy (CA 39), and Vincennes (CA 44). These cruisers all mounted the same nine 8 inch gun armament arranged in three triple turrets that the Northampton and Portland classes carried. However, the New Orleans carried that armament in turrets fully armored against direct hits from 8 inch guns, the first American treaty cruisers to do so.²⁶ Previous classes mounted their 8 inch guns in “gun houses” that afforded protection from shell fragments only, not direct hits. Construction and Repair also upgraded the protection around the magazines and machinery of this design, with the intent of creating a “zone of immunity” in which the ship was immune from 6 inch gun fire, while a 6 inch gun equipped opponent would still be within range of the cruiser’s 8 inch guns.²⁷

The signing of the London Treaty of 1930 by Britain, the United States, and Japan marked a turning point in interwar cruiser construction. If the Washington Naval Treaty primarily regulated capitol ships, the London Treaty focused much more on lesser combatants such as cruisers. The London Treaty differentiated cruisers for the first time based upon their armament. Ships with guns 6.1 inches in diameter or larger became heavy cruisers, while ships with guns smaller than 6.1 inches became light cruisers. Furthermore, the London Treaty extended the total tonnage maximum and ratios placed on battleships and carriers by the Washington Treaty to cruisers. The United States was left with 180,000 tons for heavy cruisers and 143,500 tons for light cruisers for a total of 323,500 tons for cruisers of all types.²⁸ When the aggregate tonnage of current ships was subtracted, there was only about 73,000 tons available in the light cruiser category for new construction.

As a result of the London treaty, the US Navy turned from the 8 inch cruiser to build the Brooklyn class of light cruiser. This nine ship class included the Brooklyn (CL 40), Philadelphia (CL 41), Savannah (CL 42), Nashville (CL 43), Phoenix (CL 46), Boise (CL 47), Honolulu (CL 48), St. Louis (CL 49), and Helena (CL 50) and was completed between 1937 and 1939.²⁹ At nearly 10,000 tons, the Brooklyn class displaced as much as the New Orleans class heavy cruisers they followed. These ships were armed with fifteen 6 inch guns arranged in five triple turrets with three forward and two aft. The middle turret of the forward three superfired over the other two, while the third forward turret pointed directly aft when trained in.

The US Navy adopted this gun configuration in order to maximize the number of guns carried while minimizing the magazine area to be protected. This gun plan also avoided the excessive top weight that would have resulted from placing three turrets in a superfiring arrangement. For these reasons, the contemporary Japanese Mogami class cruisers and the British Nelson class battleships also adopted this gun arrangement. The 6 inch guns carried by the Brooklyn class were of a new and improved type. They utilized what was referred to as “semi-fixed” ammunition, meaning that the shell and propellant were both contained in a single casing.³⁰ The smaller size of the 6 inch gun and its ammunition meant that hand loading was possible, and this granted a much greater rate of fire compared to 8 inch guns. The advantages of the 6 inch gun discussed by the General Board in 1921 thus finally came into play with the Brooklyn class.

While the London Treaty of 1930 directed the attention of the US Navy towards building light cruisers, it did not completely halt heavy cruiser construction. The Navy commissioned two additional heavy cruisers in 1934 and 1935 to take advantage of excess tonnage left over by weight savings in previous ships. One of these heavy cruisers was the Vincennes, the last of the New Orleans class, and the other ship was the Wichita (CA 45), the only ship of her class. Based on the hull design and machinery of the Brooklyn class, the Wichita carried barbettes and magazines redesigned to accommodate nine 8 inch guns arranged as in previous heavy cruiser designs. The 8 inch guns were of a new type, and were mounted slightly further apart in their turrets than they were in previous designs.³¹ Experience with earlier cruiser designs revealed that firing three 8 inch guns simultaneously in close proximity to each other caused the muzzle blast to interfere with the projectiles early in their flight. This interference resulted in an unacceptable dispersion pattern at battle ranges. Spacing the guns further apart and firing the middle gun separately from the outboard pair helped to alleviate this problem.³²

The Brooklyn class and the Wichita featured a number of changes over previous cruiser designs. First, these two classes had a flush deck that gave them greater freeboard. This in translated into better sea keeping and increased hull depth at the stern that allowed for placing the aircraft hangar there, along with the catapults.³³ Placing the aviation facilities in this location as opposed to amidships reduced top weight and reduced interference from the superstructure. The Wichita and the last two ships of the Brooklyn class also featured improved boilers that allowed for a decrease in the amount of space devoted to machinery and mounted the 5 inch 38 caliber dual purpose (DP) gun in their secondary battery. This 5 inch gun also formed the main battery of the last of the interwar American cruiser designs, the Atlanta class.

The Atlanta class light cruisers resulted from the second London Naval Treaty, signed in 1936. The British, still reeling from the Japanese announcement to withdraw from all naval treaties in 1934 and the construction of 10,000 ton light cruisers, made one last attempt to limit arms through negotiation. Among its other clauses, the second London Naval Treaty removed the overall tonnage quotas, but reduced the maximum displacement of individual ships to 8,000 tons.³⁴ In response to this treaty, the US Navy laid down the Atlanta 1940, four years after the last of the Brooklyn class. The Atlanta class is thus considered here as an interwar design, even though she was not completed until several weeks after the Japanese attack on Pearl Harbor. Atlanta was the first cruiser of less than 10,000 tons to be laid down by the US Navy since before World War I, and she mounted sixteen 5 inch DP guns in eight dual turrets and carried eight torpedoes. Thus, in many ways she was an intermediary between the 10,000 ton treaty cruiser and the destroyer just as the Omaha class scout cruisers were intermediaries between the WW I four piper destroyer and the armored cruiser.³⁵ Ultimately, these ships came to be regarded by the Navy as anti-aircraft cruisers, since World War II proved the effectiveness of the 5 inch 38 cal. gun when used in that role.³⁶

However, the Atlanta class came to be something of an aberration in US cruiser design. With the coming of World War II and the ending of treaty limitations, the Navy began a massive construction program for heavy cruisers and light cruisers to bolster the limited number of treaty ships. America built an astonishing 24 Baltimore class heavy cruisers and 40 Cleveland class light cruisers during the war. Both classes were much more closely related to the Wichita and Brooklyn classes than to the Atlanta. The Baltimore class carried the standard American heavy cruiser armament of nine 8 inch guns, same as the Wichita. The Cleveland class ships carried three less 6 inch guns than the Brooklyn, but mounted a heavier secondary armament to compensate.³⁷ While both the Baltimore and Cleveland classes were freed from tonnage limitations and were thus considerably heavier than their predecessors, they were nevertheless directly derived from the last of the treaty designs. As a result, the protection on both classes of these ships was not significantly greater than it was in the Brooklyn and Wichita class.³⁸

The mass-produced wartime cruisers were not the ideal ships envisioned in the interwar period the General Board. Naval officers wanted cruisers that were fast, well protected, and heavily armed, but technological limitations prevented naval architects from producing a ship with equally optimal characteristics in all areas on a displacement limited to 10,000 tons by treaty. While the coming of war removed treaty limitations, it did not also allow for sufficient time to develop cruiser types that were completely optimized and could be put into immediate production. Thus, the interwar cruiser designs of the US Navy had considerably long lasting consequences. The treaty cruisers formed the nucleus of the US Navy’s surface screen when war began, and under the pressures of rapid expansion to meet a two ocean war the Navy was forced to base its initial designs on the treaty-limited ships constructed during the interwar period.

Friedman, Norman. U.S. Cruisers: An Illustrated Design History. Annapolis: Naval Institute Press, 1984.

Terzibaschitsch, Stefan. Cruisers of the US Navy 1922-1962. Translated by Harold Erenberg. Annapolis: Naval Institute Press, 1984.

United States Navy Department General Board. Hearings Before the General Board of the Navy, 1917-1950. Wilmington: Scholarly resources Incorporated, 1983. Microfilm.