Baltimore class cruiser

madmanthan21 · November 17, 2012

The Baltimore class cruiser was a type of heavy cruiser in the United States Navy from the last years of the Second World War. Fast and heavily armed, ships like theBaltimore cruisers were mainly used by the Navy in World War II to protect the fast aircraft carriers in carrier battle groups. With their strong anti-aircraft armament, Baltimorescould contribute especially in air defenses of these battle groups. Additionally, their 8-inch main guns and smaller medium guns were regularly used to bombard land targets in support of amphibious landings. After the war, the ships were, for the most part, moved to the reserve fleet but then reactivated for the Korean War. By 1971, all ships based on the original design were decommissioned. However, four Baltimore class cruisers were refitted and converted into some of the first guided missile cruisers in the world, becomingAlbany-class and Boston-class cruisers. The last of these was decommissioned in 1980. No example of the Baltimore class still exists.

Planning and construction

Immediately after the outbreak of World War II in September 1939, the US Navy initiated studies regarding a new class of heavy cruiser, which eventually led to the construction of theBaltimoreclass. With the start of the war, the limitations instituted by theSecond London Naval Treaty, which had completely banned the construction of heavy cruisers, became obsolete. TheBaltimoreclass was based partly on theUSS Wichita, a heavy cruiser from 1937, which represented the transition from inter-war to Second-World-War designs. It was also based partly on theCleveland class, alight cruiserthat was then being built. In profile theBaltimores looked very much like theCleveland-class light cruisers, the obvious difference being that the largerBaltimores carried nine 8-inch (200 mm) guns in three triple turrets, compared to the 12 6-inch (150 mm) guns in four triple turrets of theClevelands.

The construction of the first four ships of the Baltimore class was launched on July 1, 1940 and four more were ordered before the year was out. A second order, which consisted of 16 more ships, was approved on August 7, 1942. The completion of the ships was delayed, because the Navy gave priority to the construction of the lighterCleveland-class ships, as more of the lighter ships could be completed more quickly for deployment in carrier groups. With the construction of the first eight Baltimore class ships moving slowly, the US Navy used the time to review the initial plans and improve them. The new, modified design was itself delayed, so that construction had begun on a further seven ships--for a total of 15--using the original design before the revisions were completed. The final nine ships ordered were converted to the second, modified design. Between 1943 and 1946, 14 ships of the Baltimore class entered service. Construction of the fifteenth ship, which would have been the Norfolk, was stopped at the end of the war after eight months of work had already been done, and the half-completed hull was scrapped.

Service

Of the fourteen completed ships, twelve were launched before the Japanese capitulation on September 2, 1945, though only seven took part in the battles of the Pacific Theaterand one in the European Theater. The other ships were still completing their testing in the final days of the war. By 1947, nine of the Baltimores had been decommissioned and placed in the reserve fleet, while five (Helena, Toledo, Macon, Columbus, and St Paul) remained in service. However, at the start of the 1950s, six were reactivated (Macon had been decommissioned for four short months: June–October 1950), making ten available for deployment in the Korean War. Six of these were used for escort missions and coastal bombardment in Korea, while the other four reinforced fleets in other areas of the globe. The remaining four remained out of service: the Fall River was never reactivated, the Boston andCanberra were refitted as Boston-class guided missile cruisers (CGs), and the Chicago was reactivated after being converted to an Albany-class CG.

After the Korean War, beginning in 1954 with Quincy, some Baltimores were decommissioned for good. By 1969, five ships were still in commission; four (Boston, Canberra,Chicago, Columbus) as CGs, and only one unmodified ship, the Saint Paul, which remained active to serve in the Vietnam War, providing gunfire support. St Paul was the longest serving (26 years) member of the class, and was finally decommissioned in 1971. Boston andCanberra retired in 1970, Columbus in 1975, and finally Chicago in 1980. All fourteen of the original Baltimores were sold for scrap after being decommissioned, with Chicago being the final one broken up in 1991.

In World War II, only the Canberra was damaged through enemy fire, when she was struck with a compressed air torpedo on October 13, 1944, which killed 23 men in the engine room and left the ship immobilized. The ship was hit amidships and both boiler rooms were flooded with 3,000 tons of seawater. She was towed away by sister Boston, and as a result both ships missed the crucial Battle of Leyte Gulf. A year later, repairs were completed at the Boston Naval Shipyard and Canberra was assigned to the Atlantic Fleet. In June 1945, the Pittsburgh had her entire bow ripped off in a typhoon, but there were no casualties. The ship struggled through 70-knot (130 km/h) winds to Guam, where provisional repairs were made before sailing to the Puget Sound Naval Shipyard for a full reconstruction. Pittsburgh's detached bow stayed afloat, and was later towed into Guam and scrapped.

During the Korean War, a fire in a forward turret on April 12, 1952 killed 30 men on the St Paul. Then, in 1953, the same ship was hit by a coastal battery, though without injury to the crew. The Helena in 1951 and the Los Angeles in 1953 were also struck by coastal batteries without injuries during the war.

In June 1968, the Boston, along with its escort, the Australian destroyer HMAS Hobart, were victims of friendly fire when planes of the US Air Forcemistook them for enemy targets and fired on them with AIM-7 Sparrow missiles. Only Hobart was seriously damaged; although the Boston was hit, the warhead of the missile failed to detonate.

Refittings (Albany and Boston classes)

By the latter half of the 1940s, the navy was planning warships equipped with missiles. In 1946 the battleship USS Mississippi (BB-41) and in 1948 theseaplane tender USS Norton Sound were converted to test this idea. Both were equipped, among other weapons, with RIM-2 Terrier missiles, which were also used after 1952 on the first series of operational missile cruisers. Two Baltimore-class cruisers were refitted in this first series, the Boston and the Canberra. These were the first operational guided missile cruisers in the world. They were designated the Boston class and returned to service in 1955 and 1956 respectively, reclassified as CAG-1 and CAG-2--"G" for "guided missile" and maintaining the "A" because they retained their heavy guns

In the following years six ships of the Cleveland class were equipped with guided missiles and in 1957 the first ship designed from the start to be a missile cruiser was completed (the Long Beach). Ships also continued to be converted, so starting in 1958, two Baltimore-class cruisers, the Chicago and the Columbus, along with an Oregon City class cruiser, the Albany, were converted to the new Albany class cruiser. These were launched in 1962 and 1964, respectively. Two more ships were planned to be refitted asAlbanys, theBaltimore-class Bremerton and another Oregon City-class cruiser, the Rochester but these conversions were cancelled on financial considerations. As opposed to the Boston-class refit, the Albany-class refit required a total reconstruction. Both entire weapons systems and the superstructure were removed and replaced with new ones; the cost of one refit was $175 million. Because no high-caliber weapons were used, the Albany class ships received the designation CG.

Hull

Baltimore-class cruisers were 673 feet 7 inches (205.31 m) long and 70 feet 10 inches (21.59 m) wide. Since the hull was not altered in either theAlbany or the Boston class, these numbers were the same for those ships as well, but the alterations differentiated them in all other categories.

Fully loaded, original Baltimores displaced 17,031 long tons (17,304 t) of water. Their draft was 23 feet 11 inches (7.29 m). At the bow, the top level of the hull lay 33 feet (10 m) above the water; at the stern, 25 feet (7.6 m). The funnels were 86 feet (26 m) high, and the highest point on the masts was at 112 feet (34 m). The superstructure occupied about a third of the ship's length and was divided into two deckhouses. The gap between these housed the two thin funnels. Two masts, one a bit forward and the other a bit aft of the funnels, accommodated the positioning electronics.

The vertical belt armor was 6 inches (150 mm) thick and the horizontal deck armor was up to 3 inches (76 mm) thick. The turrets were also heavily armored, between 3 and 6 in thick, while the command tower had the thickest armor, at 8 inches (200 mm).

The Boston class had a draft about 20 inches (half a meter) deeper in the water, and displaced about 500 long tons (510 t) more water than their former sister ships. Because theBostons were only partially refitted, the forward third of the ship remained virtually untouched. The first serious change was the combination of what were two funnels on theBalitmores to just one, thicker funnel, which still stood in the gap between the two deckhouses. Because the missiles required more guiding electronic systems, the forward mast was replaced with a four-legged lattice mast with an enlarged platform. The most conspicuous change was of course the addition of the missile-launching apparatus and its magazine of missiles, which took up the entire back half of the ship and replaced the guns which had been there.

The three Albanys were completely rebuilt from the deck level up, to the point that they bear very little resemblance to their former sister ships. The deckhouse now took up nearly two thirds of the ship's length and was two decks high for almost the entire length. Above that lay the box-shaped bridgewhich was one of the most recognizable markers of the class. The two masts and funnels were combined into the so-called "macks--a portmanteauword combining "mast" and "stack" (smokestack)--where the electronics platforms were attached to the tops of the funnels rather than attached to masts rising all the way from the deck. The highest points on the forward mack was more than 130 feet (40 m) above the water line. Such heights could only be achieved with the use of aluminum alloys, which were used to a great extent in the construction of the superstructures. Despite, this the fully loaded displacement of the Albanys grew to more than 17,500 long tons (17,800 t).

Propulsion

The Baltimore cruisers were propelled with steam power. Each ship had four shafts, each with a propeller. The shafts were turned by four steam turbines, the steam produced by four boilers, which at full speed reached pressures of up to 615 pounds per square inch (4,240 kPa). The Baltimores each had two engine rooms and two funnels, though this was changed in the Bostons, which only had one funnel for all four turbines, as noted above. The high speed was around 33 knots (61 km/h) and the performance of the engine was around 120,000 horsepower (89 MW).

The original Baltimores could carry up to 2,250 long tons (2,290 t) of fuel, putting the maximum range at a cruising speed of 15 knots (28 km/h) at about 10,000 nautical miles (19,000 km). The increased displacement of the modified Boston and Albany classes meant their range was reduced to about 9000 and 7,000 miles (11,000 km) respectively, despite increases in fuel capacity to 2600 and 2500 tons.

Armament

The main armament of the Baltimore class consisted of three turrets, each with three barrels, a caliber of 8 in (203mm), and were 55 calibers long (440in/17.32m). Two of these were located forward and one aft. The range of these guns was 17.3 miles (27.8 km). The secondary weapons were six twin-turreted 5 in (127mm) guns, 38 calibers (190 in/7.48m) long. Two turrets were located on each side of the superstructure and two behind the main batteries. These guns could be used against aircraft, ships, and for coastal bombardment. Their range for surface targets was 10 miles (16 km) and they could reach airplanes at altitudes of up to 6 miles (9.7 km). In addition, the ships had very strong purely anti-aircraft defenses: 12 quadruple mounts ofBofors 40 mm (or 11 quadruple mounts and 2 twin mounts on ships with only one rear airplane-crane) as well as between 20-28 20mm machine guns, depending on when a given ship was commissioned. The small-caliber weapons were soon removed. The 20mm anti-aircraft guns were removed without replacement shortly after the war because they had been ineffective against Japanese planes. The 40mm Bofors were replaced with