Saimei Class Heavy Cruiser (Part 1, 1928-1940):
By 1924 Light Cruiser production for Koko no Kaigun was in full swing, with no less than sixteen units already in service or under construction. As the Naval Staff considered such number to be largely adequate (The IJN had the same number of modern units ins ervice or under construction too) building priorities switched towards larger Heavy Cruisers. As it was common and accustomed practice KnK looked at IJN designs for simplicty and commonality, ultimately focusing on the Aoba and Myoko classes.
The smaller Aoba design was chosen, but with many features from the Myokos incorporated into the design. Armor was increased in thickness from 75mm to 100mm, with 75mm extensions that connected to the main gun barbettes with diagonal, internal, bulkheads. Barbettes themselves were 75mm, deck 35mm and turret armor was 25mm thick. The hull was modified accordigly to support the extra weight of the armor, with a beam of 16,4 meters, draft was 5,71m. The charachteristic ondulating line of the hull was simplified towards the stern, and the curvature of the bow was modified into a more pronunced stem to reduce sprays over the foredecks, increasing the overall lenght of the ships to 185,7m, roughly 0,6m more than a standard Aoba class. Twelve all-oil-firing boilers were also installed generating 114.000shp and powering four sets of geared turbines driving as many propellers for an expected top speed of 35 knots. Endurance was planned at 6.000 nautical miles at 14 knots. Armament was the same as the Aoba class, with six 200mm/50 guns in three twin turrets, four 120mm/45 single anti-aircraft guns and two 7.7mm machine guns, just the main gun turrets were of a modified design, more similar to those fitted on the Moyko class.
Approved in 1925 as class of two, the first ship was laid down at Toumachi Naval Arsenal in 1926, launched in late 1927 and finally commissioned in spring 1928. The cruiser, named Saimei, meet all her expected requirements, reaching 35knots with ease during her trial runs in Toumachi bay. Externally, the ship was quite similar to the Aoba class from which she had derived, hull lines differed slighlty from that of her half-siblings, and superstructure and bridge platforms were also arranged disfferently, with larger bridge greenhouses, larger spotting platforms and 1,5m rangefinders fitted on both sides of the fire-control tower. hangar for the spotting floatplane also lached the sloping roof in it's forward part. during the same years she was commissioned, Saimei became the first ship in Koko no Kaigun to be fitted with an aircraft catapult, much like Kinugasa did for the IJN. Nominally claimed to be a 7.100T unit like the Aoba or the furutaka class, Saimei truly displaced some 8.295T instead. Between 1928 and 1931, she formed Sentai 3 with the light cruiser Yakogoro while her sister was beign built.
The second unit of the class, Nanto, was laid down in early 1928 at Toumachi naval Arsenal, a few months her sister had been launched. Construction went on untill the hull cleared the slipways by mid 1930. As the London Naval Treaty intervened, precluding Koko no Kaigun building plan for cruisers to proceed as planned, the Naval Staff decided to delay Nanto's completion in order to fit more advanced equipment on her. The main gun turrets were switched with the newer Model-E 203mm/50 that equipped the japanese Takao class (the discarded turrets were reused for coastal-defence purposes), the 120mm guns recieved shields and two 40mm machien guns replaced the 7.7mm ones. A more powerful Type2 catapult was fitted instead of the Type1 of Saimei. The more striking differencies ere in the bridge structure though: a more advanced fire-control equipped was fitted, with the entire bridge beign relocated one deck higher, the RDF eqipment was moved to the former bridge area, with two enclosed lookout posts were fitted on each side. The 1,5m navigationr angefinders were also relocated, and were of a newer model. Such fitted Nanto was commissioned in December 1931, joining her sister's Sentai.
After six years of service as the sole Heavy Cruisers of KnK both sisters entered the yards for their main reconstructions, emerging as two deeply changed units that looked more alike to each other than they were before. New fire control equipment was fitted, with a main director set with a 6,5m rangefinder mounted atop the main superstructure and a single backup director between the funnels and the mainmast. Another set with a director and a 4,5m rangefinder was fitted on each side of the birdge structure to control anti-aircraft guns. the 7.7mm machine guns from Saimei and the 40mm ones from Nanto wrere landed, replaced by four twin 25mm machine guns at midship and a quadruple 13mm one above the RDF room, maghine gun directors were fitted abreast the after funnel. The searchlight platforms rearranged and relocated, with the searchlights themselves (originally five, split between three 110cm and two 90cm ones) replaced by three moder 110cm "shiki" ones. The aft sperstrcture was completely reworked, with the aircraft hangar replaced by an open platform housing two Nakajima E8N. The former hangar space was converted into a torpedo deck, housing two rotating quadruple sets for the 610mm Long Lance torpedoes, both augmented by two armored boxes containing as many reloads, the former twelve hull-mounted sets were removed, freeing much needed crew space. Saimei had her bridge relocated and enclosed one deck higher, Nanto, already featuring that particular arrangement, had hers just enlarged and upgraded. Saimei also had the 200mm/50 main gun barrels replaced with the newer 203mm/50 ones, her turrets were not replaced though, this created a small anomaly between the two sisters, with Nanto beign able to elevate her guns up to 70° (although only up to 55° was considered pratycal) and Saimei only up to 40°. The Naval Staff planned to rectify this problem by exploiting the already reopened production lines for heavy Cruisers by building some more extra turrets in order to replace Saimei older ones. All the modification eventually increased displacement of both ships, in order to avoid the draft from increasing too much and to improve stability, torpedo bulges were added, bringing the ships beam to 17,6m. The bulges improved torpedo defense and also expanded bunkerage, allowing the range to remain at 6.000nm. engines were refurbished but not increased in power, thus the top speed dipped slightly to 34,5knots. Post-refit standard displacement was 8.902T standard, with full load exceeding 10.000T.
Joined in the fleet by the newer Senjo class Heavy crusiers, soon followed by the Goryo class, the two Saimeis formed Sentai 4 up to the start of the Pacific War.
Ships in class: (laid down-launched-commissioned - fate)
Saimei 1926-1927-1928 - ?
Nanto 1928-1930-1931 - ?