Rivadavia at her builders' yard, shortly before trials, ca. 1914. Note she is still under US flag.
Rivadavia on trials, ca. 1914.
The Rivadavia class was authorised in 1908 primarily as a response to the Minas Gerais class being constructed in Brazil. An intense internal debate took place in Argentina concerning the need to purchase two such expensive dreadnoughts, costing £2.2 million each. Argentina's recent border Controversies with Brazil, Chile, and Uruguay helped win the day for those in favour.
The Argentine method for acquiring the best possible design stirred controversy among the building nations. In 1908 Rear-Admiral Onofre Betbeder set up office in London and requested all interested patties to submit plans for the construction of two dreadnoughts with the option to build a third. The guidelines were sketchy to allow the bidders to develop the best possible plans. Fifteen companies submitted plans. The Argentinians reviewed the submissions, chose the best features from each and gave the revised guidelines to the competing firms. This process was then repeated. The competitors were in a furore and considered this as a looting of their trade secrets.
The contract was awarded to Fore River Shipbuilding Corporation of Quincy, Massachusetts, at a saving of over £224.000 per ship over the nearest competitor. European builders were shocked because the United States, which then lagged far behind Great Britain and Germany in the dreadnought race, was not considered to be a serious competitor.
The Rivadavia class closely paralleled American battleships in appearance and design. The machinery was placed amidships with the boilers grouped in separate rooms equally forward and abaft the engine room. This arrangement reduced trimming problems and separated machinery vitals into three separate compartments.
The 'en echelon' 12in amidships turrets could in theory fire on a 180-degree arc on the side of the ship were located and 100 degrees on the opposite side. The secondary 6in guns were mounted on the upper deck behind 6in armour. The 16 x 4in QF guns were for protection against torpedo attack; 8 of these guns were mounted in the between decks, 4 on the gun deck aft, and 4 on the upper deck forward. The 8 remaining guns were located on the-weather deck 6 on the superstructure deck and 2 on the upper deck aft. The 4in guns were not protected by armour. Two submerged side-loading TT were located in the torpedo room forward, firing broadside. The ships' magazines stowed 120 rounds of 12in shell per gun, 300 rounds for each 6in, 350 rounds per 4in gun and 16 Whitehead torpedoes.
The ships were initially fitted with two 15ft Barr Stroud rangefinders mounted in revolving armoured towers above the forward and after CT for controlling the 12in guns. Two 9ft Barr Stroud were mounted on the platform on top of the king posts for the boat booms.
Typical of American-built dreadnoughts, protection received special attention. The main belt was 12in amidships tapering to 5in and 4in at the stem and stern respectively. The belt extended 5ft above and 6ft below the normal waterline. The turret armour was 12in on the face, 9in on the sides, 9.5in on the rear and 4in on the top. The forward and aft CT were 12 and 9in respectively. The protective deck extended the ship's length 24in above the waterline amidships, sloping down to the lower edge of the main belt armour. The protective deck varied from 20lb medium steel to 80lb of nickel steel. The inner bottom extended most of the length of the ships. An inner skin was fitted around the magazines, boilers, and machinery. This was for added protection against mines and torpedoes.
The electrical plant consisted of 4375kW turbogenerators located under the midship magazines forward and aft of the engine rooms. Two 75kW generators run off of diesel engines provided electricity when the boilers were cold. An 8kW Telefunken radio had an optimum range of 1500km.
The USN Board of Inspection and Survey for Ships made the following observations concerning Rivadavia on 21 October 1913. "On the high speed runs the vessel made the exact contract speed, 22,5 knots; but it is believed that she can do a little better She . . . handles remarkably well . . . The Board prefers our adopted centerline arrangement of turrets [Wyoming class]. While theoretically the Rivadavia has an ahead and asteru fire of six guns, this is not so in reality, as it is almost certain that the blast from the walst turret guns would dish in the smokepipes and damage the uptakes... The Bethlehem Steel Company designed and made special [12in guns] breech-blocks, all of which were rejected and the regular US Navy type of breech-block was finally made and installed. With comparatively minor modifications the vessel would practically meet the requirements of our own vessels."
A third dreadnought was authorised in 1912 in response to Brazil's third dreadnought, the Rio de Janeiro. Since neither this ship nor the Brazilian Riachuelo ever materialised, Argentina's third dreadnought was never laid down.
This heavy cruiser is probably one of the most slender and good looking watercraft ever surfaced the south atlantic.
These two ships ( almirante Brown and 25 de Mayo) were the most important result of the 75 million Gold Peso naval programme authorised in 1926, which formulated the requirements of the Argentine Navy for the following ten years. The contract for the two cruisers (a third was authorised but not proceeded with) was won by the Italian Odero Terni Orlando company with a design reputedly based upon the Royal Italian Navy's new Washington Treaty heavy cruiser, Trento. This ship had herself only been laid down in February 1925 and was to be followed on the same slipway at Livorno by one of the Argentine vessels, Veinticinco de Mayo. Her sister was the last vessel to be built at the La Foce yard. In fact, there appears to be little resemblance between the two designs, as the Italian ship was longer, beamier and more heavily protected than the Argentine ship. There were also differences in armament, machinery and layout. Just about all that they had in common was that both conformed to contemporary Italian design practice in that they were fast, lightly built and weakly protected, although these features were partly the result of the Treaty constraints.
Under the agreements of the Washington Treaty, all ships with guns above 8in were classed as 'Heavy Cruisers' and the Argentine ships fell into that classification, being the first and in fact only examples in any South American Navy. Argentina acquired Heavy Cruisers before several of the more recognised naval powers, and her possession of these two ships gave her a leading position amongst the 'ABC' powers on the subcontinent.
The main armament, 190mm (7.5in)/52 calibre, was unusual, only the British Hawkins class (q.v.) having the same weapon calibre as designed. These were carried in twin turrets, with two forward, having 46º elevation. Maximum range was 27.300m.
150rpg was the ship's book oufit. Secondary armament consisted of six twin 102mm (4in) O-T guns disposed on the forecastle deck amidships. These guns had a maximum elevation of 80º in the AA role. A total of 3.000 rounds was allowed for. Twelve torpedoes were carried. As built, the aircraft installation consisted of a Gagnotto fixed catapult on the forecastle in accordance with current Italian designs, with a hangar for two aircraft below. The aircraft were initially Vought Corsair O2Us, then Grumman G5s, these being replaced by the Supermarine Walrus and finally, the Grumman J2F.
25 de Mayo
25 De Mayo arrived at Alicante on 22nd August 1936 to protect Argentinian interests during the Spanish civil war and returned home on 14 December. In the late 1940s, a British radar set was fitted.