another update (and addition of WWII era) for one of my earlier cruiser classes:
Yakogoro Class Light Cruiser:
As the Naval construction plans went into late 1910s Koko no Kaigun started to plan building a new class of Cruisers to supplement the -at the time still under construction- Kashino class. Convenience and pratical reasons led to the choice of basing the cruisers on the same 5.500-ton hulls of the japanese Kuma class units. During a joint designing work between KnK and the IJN, some modifications over the preceding class were considered: removing the armored conning tower and adding an enclosed hangar to the bridge structure in anticipation of carrying a reconnaissance seaplane and adding a take-off platform i front of it. Switching from 533 to 610mm torpedoes was also envisioned. While this basic layout evolved into the Nagara class for the IJN, Kokoan designers made more modifications to it before it eventually finalized into what was then called the Yakogoro class.
Five units were ultimately ordered, three at Kousaten Navy yard and two at Toumachi Naval Arsenal. The ships were 162m long, 14,2m abeam and had a draft of 4,8. Displacing 5.535 tons at standar load (the Japanese Nagaras ended up displacing 5.570T), the ships had an angled stem line (contrary to the curved one of the Nagaras) and retained an auxiliary conn station near the mainmast. Ten oil-firing and two mixed oil/coal boilers powered four turbines to 90.000shp, propelling the ships up to 36knots. Endurance was 6.000 nautical miles at 14 knots. The armament differed from the Kumas and Nagaras, in layout but not in number. 7 140mm/50 Type 3 guns were fitted, but four of them were housed in two twin enclosed mounts -one forward and one aft- while the other three were in single shielded positions. Two abaft the bridge and one on centerline between the funnels and the mainmast. This allowed to retain the same six-gun broadside while increasing end-on fire to two guns aft and four forward. AA armament was composed by two 76mm guns and single 6.5mm machine guns in removable positions. four twin sets for 610mm torpedoes were fitted, two on each sides, forward and aft of the funnels.
Yakogoro, the first ship of the class, was laid down at Kousaten in 1920. Houraisan and Suzuka followed at Toumachi in 1921, then Otonase at Kousaten later the same year. Finally, Minase was laid down at Kousaten in March 1922, a month after Yakogoro's launch. All five units were still under construction when the Washington Naval treaty was signed, but works were not affected: Yakogoro was commissioned in early 1923. The ship immediately recieved a Yokosuka Ro-Go Ko-Gata floatplane, becoming the first Koko no Kaigun ship to operate a shipboard plane. Although the Ro-Go Ko-Gata was initially and extensively used only to train ship -and air- crews in seaplane handling operations.
Construction of the other four ships slowed down as there was no immediate need to rush them in service -Destroyer production had been revised and fewer units would have been built and at later dates- but no unit was ever even remotely in danger of beign canceled. Instead, Koko no Kaigun took the advantage given by the extended building time to retrofit a clipper bow on all the remaining ships, with the intent of improving handling in rough seas. Houraisan, the second ship of the class, was commissioned in January 1925, soon followed by Suzuka and Otonase. All three recieved a Yokosuka Ro-Go Ko-Gata floatplane like Yakogoro, although just Houraisan operated it for more than a few months after handling proved to be more complex and cumbersome than anticipated..
The last unit, Minase, was commissioned in December 1925 and sported some more pecultiar features if compared to her earlier sisters. As it was planned to equip her with a Yokosuka E1Y instead of a Ro-Go Ko-Gata, the taking-off platform was lenghtened by shifting the hangar backwards into the bridge structure, a thing that in turn forced the wireless room to be moved into an extra deckhouse built within the tripod mast. Two extra lookout platforms were added and two 60cm signaling searchlights carried.
All five initially made up two surface Sentai units, in the late 20's Yakogoro briefly operated as a Sensui Sentai Flagship for Submarines Ki-1 and Ki-2, Minase and Otonase became Suirai Sentai Flagships when new Destroyers finally entered service.
Under the 1st rearmament bill approved by Morimoto's government in late December 1933, a refit for the five Yakogoro-class cruisers was funded. All ships entered the yards between 1934 and 1935, with the lead ship, Yakogoro, reworked in a little more than six months.
Main modifications involved the replacement of the pole mainmast with a tripod, which was almost 4 meters shorter. The new tripod mainmast housed two platforms for a lookout post and a 90cm searchlight, a boom was also added for aircraft-handling purposes. Aviaton facilities were removed from the bridge structure and moved amidship, with a Kure Type-2 catapult fitted above the n°4 gun mount and just forward of the auxiliary conn platform. A single Yokosuka E4N reconnaissance floatplane was carried. Forward, the former hangar space in the bridge were reconverted into flag-space, effectively improving the capability of the vessels to operate as either Sensui Sentai or Suirai Sentai flagships. The now useless flying off platform was removed and replaced with an anti-air platform housing a quadruple 13mm machine gun mount. The 76mm guns at midships were also replaced by two more 13mm machine-gun mounts, this time twin ones. A radio room was added on the superstructure third level, inside the forward tripod mast legs, two enclosed lookout stations were also added. The main bridge was completely enclosed, being given full windows and a solid roof. A 4,5m rangefinder was added above the enclosed bridge and the spotting tops were vastly enlarged, with the addition of an extra level and the fitting of a lookout post. Finally, the main deck surface area was expanded, with overhangs extending on both the port and starboard side well aft of the mainmast.
Houraisan was recommissioned by the end of 1934. Her modifications slightly differed from those of Yakogoro as she recieved a newer RDF gear and a 3,5m rangefinder on top of the bridge instead of a 4,5m one. Her birdge structure was also slighlty larger, owing mor space for flag duties.
Suzuka also slighlty differed from her sisters after the refit, as she only had her portside deck extension done. also, she sported two 90cm searchlights on the mainmast platfrom instead of one. Her bridge structure featured a two-deck deckhouse for the radio-room, the enclosed lookout platform was placed more forward as the sponson housing the 60cm signalling searchlight was not removed. Finally, the bridge roof was shorter and the spotting top central platform slightly smaller.
By 1936, under the second reamament bill, a second refit for the Yakogoro class was approved. As initially concieved it called for a radical modification of the fire-control and torpedo equipment. Yet, soon focus and budget shifted to the Battleship and Carrier program, so that only Otonase and Minase entered the yards in 1937. Even so, just Otonase eventually underwent the planned refit.
The radio room was moved down a deck, two 1,5m navigation rangefinders fitted on both sides of the bridge. The lower lookout post were opened, with a 6m rangefinder replacing the earlier ,45m one aabove the bridge. The forward searchlight platforms wereexpanded, with two 100cm units replacing the older 90cm ones. The two upper levels of the spotting top were removed, the lower one was expanded and fitted with a torpedo director and a dedicated main-gun director. The overall heigt of the mast was also substantially reduced. The mainmast had it's lookout platform removed and the 90cm searchlight replaced with a 110cm one. The pole derrick for aircraf-handling was replaced with a built-up one. A Kawanishi E7K replaced the Nakajima E4N, the RDF was replaced and two twin 25mm machine guns replaced the 13mm mounts at midship. At first it was planned to have the four twin 610mm torpedo tubes beign replaced by two quadruple launchers, but a shortage in manifactured torpedo tubes, prevented this to be implemented. Thus fitted, Otonase rejoined the fleet in 1938.
Delays ultimatedly prevented Minase to recieve the same modifications as Otonase, so that just a minor refit was done. The cruiser recieved the newer 110cm searchlight in place of the 90cm ones, the Kawanishi E7K and the twin 25mm machine guns. Other modifications included the fitting of a built-up derrick, the installations of a new 4,5m rangefinder unit and the shorteing of the foremast. Minase rejoined the fleet in 1939. The other thrre cruisers recieved minor improvements, like the upgrade of the anti-aircraft suite.
By early 1940, Houraisan also entered the yards for a minor refit. During works the foremast was shortened and the fire control updated. The spotting top was removed and a director fitted in its place, the 3,5m rangefinder over the bridge was replaced with a 4,5m one. The pole derrick for aircraft-handling was replaced with a built-up one and a newer Kawanishi E7K floatplane carried. Finally, the RDF was upgraded, the twin 13mm machine guns were replaced by 25mm twins and a dozen depth charges with two throwers carried on board.
Eventually, all cruisers with the exception of Houraisan finally underwent the more comprehensive refit that had initially been planned for 1936. Yakogoro was the first to go through it in the later months of 1940. She had her foremast shortened, a director for the main guns fitted in place of the spotting top, her 90cm searchlights replaced with 110cm ones and the lower fire-control platform expanded aft to fit a torpedo director. Two twin 25mm machine guns were fitted abreast the fore-funnel in place of the older 13mm ones. The RDF fit was modernized and the aircraft-handling crane replaced in order to operate an E7K floatplane, a dozen depth charges were carried. Finally, the forward twin torpedo tubes were removed and the deck enclosed to make room for more crew-spaces. The aft launchers were replaced by quadruple ones.
Suzuka followed during the first half of 1941. She mainly followed the same modifications made to Yakogoro bar a few exceptions. All lookout posts lost their shield covering or glass enclosings, two 1,5m navigation rangefinders were fitted, a 6m rangefinder replaced the 4,5m one for gunfire control.
Otonase, which had already been extensively refitted earlier only recieved the torpedo tube upgrades and had depth charges fitted during her docking time in fall 1941.
Minase was the last to get modified and did so in two stints. She first got all her fire-control upgrades between october and november 1941, and then underwent the torpedo tubes swap in January 1942.
When the Pacific War started Minase and Otonase took part in the operations around Midway and its subsequent occupation, they were then sent to support operation in the Dutch East Indies where they took part, together with the Amagi, in the naval battle of Balikpapan agaist British and Recerhean units. Then supported the Japanese carrier operations in the Indian Ocean and fought in the battle of Bay of Bengal, once again with Amagi and, this time, Kii and Owari as well. Both came back to Koko to take part in the AL/MI operation (invasion of the eastern aleutians and ambush of the American carrier fleet), but like all other Japanese and Kokoan surface fleets took no part in the -disatrous- carrier battle.
Yakogoro, Houraisan and Suzuka recieved arctic camouflage and were deployed to the Aleutians, were hey took part in the invasions of Attu, Kiska, Adak and Atka. All three had and remained stationed in the area until late october, when Houraisan was detached. Docked and repainted in standard gray at Toumachi Naval Arsenal Houraisan eventually joined Minase and Otonase at Truk to support operations in the Solomon theatre. The three cruisers remained there until August 1943, taking part and supporting every operation in those waters. Suzuka and Houraisan life in the Aleutians was instead almost uneventful in the meantime.
Slighlty damaged by near misses during the battle off the Frigate Shoals (also known as battle off Gardner), Minase returned home for repairs and refit, during which she was fitted with a Type 13 radar. Also, AA armment was augmented by the addition of two triple 25mm machine guns near the catapult and the removal of the aft twin 140mm gun mount, replaced by a twin dual-purpose 127mm one.
Suzuka and Otonase also got their first wartime refit between october and november 1943. The first had a Type21 air-search radar fitted on the foremast in place of the main gun director. The anti-air platform in front of the bridge was expanded, and the single quadruple 13mm machine gun mount removed in favour of two twin 25mm ones. Finally the n°4 gun mont was landed with two more 25mm machine guns, this time triples, fitted. The space was also used to embark two daihatsu landing crafts.
Otonase was refitted in the very same lines of Suzuka. In anticipation of its planned redeployment to the Aleutians, she recieved arctic camouflage as well. Her new service life in northern waters was short however, as the ship was sunk on December 19th during the Naval battle of Unalaska.
Houraisan, which had been left operating south in the Solomons theatre suffered heavy damage on January 11th 1944 when she was caught by land-based Recerchean planes after a bombardment mission on US positions in New Georgia. In addition to a few less serious hits and a couple of near misses one bomb had completely obliterated the bridge killing the entire senior crew. After temporary repairs at Truk Houraisan sailed to Hoshiguma to underwent three monts of extensive repairs. During works the bridge structure was lowered from five to four levels. The radio room was lowered by two levels and the two-level fire-control platform was merged and expanded into a single one, also lowering the overall height of the foremast. A type21 air-search radar was fitted, a 6m main-gun rangefinder replaced the older 4,5m one, a torpedo director was fitted, as well as two 1.5m navigational rangefinders on each sides of the bridge. All three 90cm searchlights (two on the foremast and one on the mainmast) were replaced by 110cm ones. The quadruple 13mm machine gun fitted in front of the bridge was moved between the first and second funnel, in place of one of the auxiliary rangefinder platforms. The forward anti-air platform was expanded and two twin 25mm machine gun mounts added, as well as two triples near the aircraft catapult. The aft twin 140mm gun mount was replaced by a twin 127mm one. Two depth change rails were added aft (increasing stowage to 24 warheads) and an hydrophone was installed forward. Finally, all lower deck porholes were sealed off to increase watertight integrity. Overall, Houraisan was the only cruiser of the class to retain the four twin torpedo tubes for its entire life. After taking part to the indecisive battle of Laysan and the disastrous second battle of Midway, Houraisan was redeployed to the Aleutians -this time without getting any camouflage scheme- where she would be sunk by US submarines in november 1944 roughly 220 miles east of Adak.
In April 1944 Suzuka recieved an upgrade of her anti-air armament during a minor refit in Kumoi. The aft 140mm gu mount was removed, and a 127mm one fitted in its place. Machine gun positions were augmented to reach a total of three triple, six twin and ten single 25mm machine guns (31 barrels) plus six twin and a quadruple 13mm mounts (16 barrels). A type22 surface-search radar was fitted and all lower deck portholes were closed.
Yakogoro finally entered the yards for her much needed first major wartime refit in May 1944. She recieved both a Type21 air-search and a Type22 surface-search radar. The aft twin 140mm mount was replaced by a twin 127mm one. Light anti-air suite was increased to a total of five triple, eight twin and four single 25mm machine guns, for a total of 35 barrels. Two twin and one quadruple 13mm mounts were also carried. Two depth charge rails were fitted aft, with stowage increased to 24, and an hydrophone was fitted. All lower-deck portholes were sealed off.
This did not prevent the three suviving cruiser from getting repeatedly damaged in the face of growing American air power. It was thus decided to refit them into anti-air cruisers.
Suzuka was the first to enter the yards in October 1944. all her remaining 140mm guns were landed and replaced by two more twin 127mm mounts (for a total of six). Machine guns were increased to eleven triple, two twin and twenty-two single 25mm mounts (59 barrels), with all 13mm mounts removed. Fore and aft superstrucutes were modified to fit a Type21 ar-search radar, Type22 surface-search, TypeR2FA air-search and Type12RCAD anti-air fire-control radar. Two rails and new throwers were fitted for depth-charges, whose number was increased to 48 warheads. A sonar system was installed, the aircaft catapult was removed and more portholes were sealed. A blue stripe was added on the hullc amouflage. Suzuka returned into service in February of 1945.
Yakogoro followed between December 1944 and April 1945, mainly following the same lines of Suzuka. Some differencies emerged in the end. A Type24 air-search radar was fitted instead of the older Type21, and the light anti-air suite was made up by eleven triple, four twin and sixteen single 25mm machine guns (57 barrels).
The refits didnt's save neither Yakogoro or Suzuka however. The first was sunk on May 11th 1945 during the naval battle of Adak, the latter bombed by US aircrafts on August 19th, a few days after the Kiska landings.
Minase was spared from this fate because she was still being refitted at the time, being docked between April an august 1945. During works she landed all her main gun armament, both 140 and 127mm mounts, and was fitted instead with four twin 100mm guns. Minase also became the first kokoan ship to be fitted with an uniform battery of the new 40mm/type4 reverse-engineered Bofors, and was equipped with nineteen twin and eight single mounts for a total of 46 barrels. She also carried a Type33-kai surface-search radar, which could double as a fire-control unit, IFF and six machine gun director for more organized anti-air fire. The ship was also repainted in a blue-black scheme. All other modifications were in line with that of Suzuka and Yakogoro.
After taking part in the Battle of Cape Engano, Minase's crew Joined the rebels in november after the start of Koko uprisings, operating at its best in the anti-air role against IJA and loyalist planes.
After the March 1946 armistice with the US Minase was left uncrewed in Toumachi harbor. Briefly reactivated in September she acted as a repatriation vessel until December of the same year when she was decommissioned for good. Minase was eventually scrapped in 1947 in compliance with the surrendering terms.
Ships in class: (laid down-launched-commissioned - fate)
Yakogoro 1920-1922-1923 – Sunk 1945
Houraisan 1921-1924-1925 – Sunk 1944
Suzuka 1921-1924-1925 – Sunk 1945
Otonase 1921-1924-1925 – Sunk 1943
Minase 1922-1924-1925 – Decommissioned 1946