Bahia-class cruiser

The class's design borrowed heavily from the British Adventure-class scout cruisers.[1] The ships displaced 3,100 tonnes (3,100 long tons),[1][2] and their dimensions were 122.38 m (401 ft 6 in) overall, 115.82 m (380 ft 0 in) between perpendiculars, 11.89–11.91 m (39 ft 0 in–39 ft 1 in) at the beam, and a draft of 3.81 m (12 ft 6 in) forward, 4.75 m (15 ft 7 in) amidships, and 4.42 m (14 ft 6 in) aft.[2] They were powered by five Parsons steam turbines, and ten Yarrow boilers, with a coal bunker that could hold a normal load of 150 t (150 long tons), and a maximum load of 650 t (640 long tons).[3]

The Bahia class was designed to reach a speed of 26.5 knots (49.1 km/h);[2] both ships exceeded this during trials with Bahia reaching 27.016 knots (50.034 km/h) at trial.[1] As designed, the class's range was 1,400 nautical miles (2,600 km; 1,600 mi) at 23.5 knots (43.5 km/h), or 3,500 nautical miles (6,500 km) at 10 knots (19 km/h).[3] The class was armed with ten 120 mm (4.7 in)/50 caliber, six QF 3 pounder 47 mm (1.9 in)/50 caliber guns[1][2] and two 457 mm (18.0 in) torpedo tubes.[1] The class was lightly armored with only 19 mm (0.75 in) of deck armor, with the conning tower having 76 mm (3.0 in).[1]

The class was part of a large 1904 naval building program by Brazil.[5][6] Also planned as part of this were the two Minas Geraes-class dreadnoughts, ten Pará-class destroyers, three submarines and a submarine tender.[6][7] With a design that borrowed heavily from the British Adventure-class scout cruisers,[1] Bahia's keel was laid first on 19 August 1907 in Armstrong Whitworth's Elswick, Newcastle upon Tyne yard, followed by Rio Grande do Sul 30 August 1907.[1][8] Construction took about a year and a half, and both ships were launched in 1909.[5][8][upper-alpha 1] Both ships were completed and commissioned into the navy in 1910.[2] As a class, Bahia and Rio Grande do Sul were the fastest cruisers in the world when they were commissioned,[1] and the first in the Brazilian Navy to utilize steam turbines for propulsion.[2]

Bahia prior to being modernized between 1925 and 26, with a low bridge and two funnels.

Bahia post-modernization. The most striking visual changes were adding height to and adding a third funnel. Even though oil has a greater thermal efficiency, an extra funnel was necessitated by the arrangement of new oil-firing boilers, where two each were placed in three independent compartments.[9]

In the mid-1920s,[1][2][5][upper-alpha 2] the class underwent significant modernization.[2] The original five turbines were replaced by three Brown–Curtiss turbines, while the original ten boilers were replaced by six Thornycroft oil-burning boilers, which necessitated the addition of a third funnel. The former coal bunkers, along with some of the space freed up by the decrease in boilers, were converted to hold 588,120 L (155,360 US gal) of oil.[2] These changes resulted in Bahia's top speed increasing to 28 knots (32 mph; 52 km/h).[1] All of the boats on board were replaced, and three 20.1 mm (0.79 in) Madsen guns, a 7 mm (0.28 in) Hotchkiss machine gun, and four 533 mm (21.0 in) torpedo tubes were added to give the ship a defense against aircraft and more power against surface ships.[2]

The class was modernized again twice during the Second World War, in both 1942 and 1944. The modernizations were not as extensively as it was in the 1920s; the Brazilian Navy's official history of Bahia reports these but does not specify what modifications the ship underwent in which year.[2] Two 47 mm (1.9 in) guns were replaced with 76 mm (3.0 in) L/23 AA guns, Madsen guns were replaced with seven Oerlikon 20 mm cannons in single mounts, and a director for these guns was installed.[2] Two depth charge tracks were added, improved range-finders were added to the 120 mm (4.7 in) guns, and sonar and radar were fitted, in addition to other minor modifications.[2][upper-alpha 3]

On 4 July 1945, Bahia was acting as a plane guard for transport aircraft flying from the Atlantic to Pacific theaters of war. While Bahia's gunners were firing at a kite for anti-aircraft practice, one fired too low and hit depth charges stored near the stern of the ship. A massive explosion incapacitated the ship and sank her within minutes, resulting a large loss of life.[1][10][11]

• Brook, Peter (1999). Warships for Export: Armstrong Warships 1867 – 1927. Gravesend, Kent, UK: World Ship Society. ISBN 0-905617-89-4.
• Gardiner, Robert; Gray, Randal, eds. (1985). Conway's All the World's Fighting Ships: 1906–1921. Annapolis: Naval Institute Press. ISBN 0-87021-907-3. OCLC 12119866.
• Jane's Fighting Ships of World War I. London: Random House [Jane's Publishing Company]. 2001 [1919]. ISBN 1-85170-378-0. OCLC 48257502.
• Scheina, Robert L. (2003). Latin America's Wars: Volume II, The Age of the Professional Soldier, 1900–2001. Washington D.C.: Brassey's. ISBN 1-57488-452-2. OCLC 53078537.