Bahia-class cruiser

Line drawings of the Bahia class
Class overview
Name	Bahia class
Operators	Brazilian Navy
Built	1907–1910
In commission	1910–1948
Planned	3
Completed	2
Cancelled	1
Lost	1
Scrapped	1
General characteristics
Type	Scout cruiser
Displacement	3,100 t (3,100 long tons)[1][2]
Length	122.38 m (401 ft 6 in) oa 115.82 m (380.0 ft) pp[2]
Beam	11.89–11.91 m (39 ft 0 in – 39 ft 1 in)[2]
Draft	3.81 m (12 ft 6 in) forward[2] 4.75 m (15.6 ft) amidships[2] 4.42 m (14.5 ft) aft[2]
Propulsion	Five Parsons steam turbines,[3] ten Yarrow boilers[2] Coal normal 150 t (150 long tons; 170 short tons)[3] Maximum 650 t (640 long tons; 720 short tons)[3]
Speed	26.5 knots (49.1 km/h; 30.5 mph) as designed[1] 27.016 knots (50.034 km/h; 31.089 mph) trial[1] 25 knots (46 km/h; 29 mph) at full load[2]
Endurance	1,400 nmi (2,600 km; 1,600 mi) at 23.5 knots (43.5 km/h; 27.0 mph)[3] 3,500 nmi (6,500 km; 4,000 mi) at 10 knots (19 km/h; 12 mph)[3]
Complement	320[3] to 357[2]
Armament	ten × 120 mm (4.7 in)/50 caliber,[2] six × 47 mm (1.9 in)/50 caliber,[1][2] two × 457 mm (18.0 in) torpedo tubes[1]
Armor	Deck: 19 mm (0.75 in)[1] Conning tower: 76 mm (3.0 in)[1]
Notes	These specifications apply to when Bahia was commissioned.

The Bahia class was a pair of scout cruisers built for Brazil by Armstrong Whitworth in the United Kingdom, based on a design that borrowed heavily from the British Adventure-class scout cruisers. The class comprised the lead ship Bahia and her sister Rio Grande do Sul, along with a canceled third ship, Ceara.^[4] Both were named after states of Brazil. As a class, they were the fastest cruisers in the world when commissioned, and the first in the Brazilian Navy to use steam turbines for propulsion.

In the mid-1920s, both ships were extensively modernized with three new Brown–Curtis turbine engines and six new Thornycroft boilers, and, in the process, was converted from coal-burning ships to oil-burning. The refit resulted in a striking aesthetic change, with the exhaust being trunked into three funnels, instead of two. The armament was also modified; 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.

In the Second World War, both were used as convoy escorts. On 4 July 1945, Bahia was lost after an accident caused a massive explosion which incapacitated the ship and sunk her within minutes, resulting a large loss of life. Rio Grande do Sul survived the war and was scrapped in 1948.

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; 30.5 mph);^[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; 27.0 mph), or 3,500 nautical miles (6,500 km; 4,000 mi) at 10 knots (19 km/h; 12 mph).^[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] Vickers would later pitch the Bahia design to the Ottoman Navy in 1912, but nothing came of it prior to the outbreak of the First World War.^[5]

The class was part of a large 1904 naval building program by Brazil.^[6][7] Also planned as part of this were the two Minas Geraes-class dreadnoughts, ten Pará-class destroyers, three submarines and a submarine tender.^[7][8] 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][9] Construction took about a year and a half, and both ships were launched in 1909.^[6][9][A] 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.^[10]

In the mid-1920s,^[1][2][6][B] 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 (52 km/h; 32 mph).^[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][C]

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][11][12]

• 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.