The completion of the Aconagua class battlecruisers gave the Imperial Navy two types of capital ship to base the next class of Imperial battleships on. Speed or armour or a bit of both, the debate was heated with supporters of all three types. Half a dozen different designs were put forward and finally the Chief of Construction and Design chose one of the fast battleship designs. This is the end of 1911 beginning of 1912. The British are building 12 x 13.5" dreadnoughts, the Germans are building the nine Konig/Kaiser class, the US has the Texas/Oklahoma classes under construction while lastly the Japanese had started the four Kongo's. Then if that was not enough to give the Empire headaches, the Admiralty advised the Empire of the new Queen Elizabeth design and the step up to 15" guns. The 700 foot 8 x 14" design the Chief had chosen, no longer looked a world beater. The 15" 40 calibre gun of the British was purchased and the design recast to take 8 x 15" with a 28 knot speed.
What the Empire ended up with was a 780 x 98 foot fast battleship. The ships weighed in at a massive (for the time) 34,000 tons standard displacement. Armour was not stinted with a 12" armoured belt and 3.5" of deck armour. The armament was 8 x 15" in four twin turrets and these would be the last sloped armour main turrets. Secondary armament of 10 x 6" single mounts were fitted on the forecastle deck level. No casemates required. The anti-torpedo boat guns of 12 x 100mm were fitted around the superstructure and funnels. Lastly a large propulsion system of 120,000shp through four shafts produced 28 knots.
Four ships of the class were built completing in 1916-17. Each ship had taken just over 5 years to build and by the time of their completion the British had built 14 (Fisherless RN) 15" ships while the rest of the world had completed plenty more of complimentary sizes.
IS Llullaillaco. 1916. Service/Fate:
IS Huascaran. 1916. Service/Fate:
IS Quilotoa. 1917. Service/Fate:
IS Alpamayo. 1917. Service/Fate:
Imperial Ship Alpamayo, Fast Battleship.
Taken in hand for rebuilding, one per year, from 1936 to 1939, with the rebuilds taking two years each the ships re-entered service 1938-41. The Alpamayo was the third of the class to be rebuilt. The new Battleship class was being designed and built at the same time and as many parts as possible were mass produced for the eight ships of the two classes.
The rebuilding was quite a major work with virtually all of the superstructure and secondary/tertiary armaments being removed and replaced with new equipment and superstructure. When this was done the opportunity was taken to replace the old propulsion system with a new set of boilers and turbines. Technology increases meant that a similar sized propulsion package as that removed (120,000shp) produced 140,000shp for an increase of speed from 28 to 30 knots.
Armament at this stage of their careers was:
8 x 15" (4x2)
20 x 130mm (10x2)
12 x 40mm (6x2)
26 x 20mm (26x1)
4 Aircraft