Ōtori class Torpedo Boat (1935)

Imperial Japanese Navy 1937-45.
IJN Otori, Hiyodori, Hayabusa, Kasasagi, Kiji, Kari, Sagi, Hato + 8 more cancelled.

The Otori-class torpedo boat (鴻型水雷艇, Ōtori-gata suiraitei) were a second class of Imperial Japanese Navy torpedo boats built in the late interwar after the Chidori class, and improved. Their design was indeed a reaction to the Chidori class, which were an attempt to cram as much armament as possible in a hull which displacement was attempted to cheat on the Washington treaty limit of 600 tonnes (unlimited). The IJN staff after the dramatic capsizing of Tomozuru in a typhoon had to rebuilt suviving ships and change its construction policy. The planned class of sixteen vessels was cancelled and height ships on a completely revised design was born: The Otori, built 1934-37. They all took part in the Second World War in which all but one were lost in action.

The class was forced to take part in ever more dangerous actions, after the relatively “easy” Chinese campaign in 1937-1941, landing escort covers in late 1941 and early 1942. They Ōtori were used extensively, as destroyer replacements, from the start of the Pacific War. After the Philippines, Dutch East Indies and Solomon Islands campaign wit some successe. IJN Hiyodori managed also to sank USS Amberjack (SS-219) in the Solomon Islands campaign on 16 February 1943. However, losses started rapidly: Seven of the eight ships in the class were sunk in succession either by submarines or air attacks, one in 1943, and the remainder in 1944, one in 1945, between the Southern Pacific and the South China Sea, with only Kiji surviving to the end and ending as a Soviet war reparation, active until 1957.

Development

A revised design, Project F47A (1934)

Under the terms of the 1930 London Naval Treaty, the Imperial Japanese Navy still under the Washington tonnage caps for all ships type as the others and notably for destroyers, saw its reserve rapidly dwindling down with the new “special type” about to be generalized in the fleet. Even with official under-evaluation of tonnage, engineers were pushed to cram as much armament as they could on the hulls, and some suggested to take advantage of the treaty loophole of warships below 600-tons. This potential catergoey remained unadressed. It was then theorized that a samall ecort destroyer or torpedo boat of that tonnage could carry half the armament of a “special type”. It was hoped this new class would bring not further scrutiny.

Four of these new torpedo boats, a category neglected by Japan since decades, were already ordered as part of the 1931 Maru 1 Programme for escort service. However at that stage, engineers were ordered to massively arm the ships, and this first class, the Chidori, would prove over-ambitious, which was paid dearly, with the loss of IJN Tomozuru in the 12 March 1934 an enquiry led to drastic revisions of the design and reconstruction for the remaining three TBs of that class. The ambitious new class of sixteen ships fortunately was ordered, but construction was stopped. No keel was laid down besides this preserie. The sixteen vessels were not cancelled outright: It was decided to completely redraw the new torpedo boats and order sixteen of that new design.

The Otori class, were considerered a good design, more realistic for their tonnage, which went up to 840 tonnes standard, closer to a small destroyer, and already above the treaty limit, but they were more reasonable in armament, and the hull was built more strongly the the line of what happened and was suggested as fixes. The first, Otori, would be laid down in November 1934, so many months after the loss of Tomozuru. The first batch oif four was launched in 1935 and the second in 1937. The IJN recoignized they had a limited usefulness however at this point and cancelled the next eight ships and instead turned into ASW-specialzed vessels that would be a new generation of sub-chasers, large and small. The Japanese Torpedo Boats of the interwar was thus just a fad (1933-37). A total of twelve vessels were ever built, all taking part in heavy actions in WW2, with heavy losses, just like their destroyers counterparts…

The outrageous Hatsutaka class (1937)

When the Otori class was planned in 1934, the original plan for the Chidori-class torpedo boats was to build 20 of them. By 1931 with the (Showa 6) Plan construction of four of the requested 12 was approved and the following 1934 (Showa 9) Plan saw construction of 16 torpedo boats was approved, for the targeted 20 boats originally planned. The Naval General Staff made even more ambitious demands for the latter batch, lated to be named the Hatsutaka class than for the Chidori-class, still within the same 600-ton capacity amazingly. And these demands included a speed of 34 knots (Chidori-class: 30 knots) as well as a cruising range of 3,000 nautical miles at 16 knots compared to 3,000 nautical miles at 14 knots for the Chidori, four 12.7 cm guns compared to three, four 61 cm torpedo tubes compared to four 53 cm torpedo tubes. This design began under the number F47, but the Tomozuru incident led to the revisions we know, and the new design became the F47B. Initially, they were still officially under 600 tons, but in reality far exceeding the treaty limit, by 240 tonnes. Even at the initial planning stage, trial displacement in fact reached 893 tons and the final batch trial displacement jumped to 960 tons.

Design & Construction of the Otori

Construction

The IJN Otori, and her sisters of the first batch of four to be laid down in 1934-35, had the lead boat from Maizuru Naval Yard, the same that built the lead ships of the previous class. Otori was laid down on 8 Nov 1934 and launched on 25 Apr 1935, completed on 10 October 1936, so about two years, but 19 months in completion, which showed the number of modifications made as a result of the long enquiry and 4th fleet incident. Indeed it occurred while the first four ships of the Otori class were under construction. Construction was suspended, numerous design revisions were made, and resumed, with reinforcement of the welded structure, partial reinforcement with a new DS steel. The plan was revised to use all DS steel for the remaining four. Eight ships were completed between October 1936 and September of 1937, and when completed, the trial displacement was unofficially above 1,000 tons, which exceeded the treaty limit by …400 tonnes. However by that stage on 15 January 1936, Japanese delegates walked out of negotiations at the Second London Naval Conference. They were completely disregarded anyway.

The original plan called for the construction of 16 ships and construction delays meant the remaining vessels would be completed in the post-treaty era, but construction was halted after the first eight ships were built. Now there was no reasons to chat on the treaties, the IJN found that type no longer useful compared to a regular destroyer, and and no more torpedo boats would be built. To compare, the last ship of the second batch, IJN Hato was laid down at Ishikawajima Shipyards on 28 May 1936, launched on 25 Jan 1937 and completed on 7 Aug 1937, that is one year and four months, a stark contrast to the first batch. This was explained by the design being mature and no revision being done along the way. Some authors later said that if the IJN kept developing these, they would have been the base for the next mass-produced destroyers of the Matsu-class and took an advance in this type of design.

Naming

The new Torpedo Boats left to no debate about to give them numbers since it was decided after the “8-8 fleet plan” to avoid confusion in manoeuvers and maintain the esprit de corps in crews. It was decided for this new type to go for animal names, that is birds… In the earlier batch Otori was the “plover”, Manazuru the “White-naped crane”, Tomozuru ba “flight of cranes” and Hatsukari the “first wild goose of the season”, so birds with a poetic twist. The next Otori class continued this naming tradition of (partly migratory) birds: Ōtori was the “stork”, Hiyodori a “brown-eared bulbul”, Hayabusa the “peregrine falcon” (also chosen for the excellent army fighter ki-43), Kasasagi the “magpie”, Kiji the “pheasant”, Kari the “Wild goose”, Sagi the “snowy heron” and Hato the “dove”.

Hull and general design

The Chidori-class saw its speed reduced to 27-28 knots due to repeated modifications increasing the displacement, a far cry to the 35 planned initially, so the new Otori class was designed to restore this speed to 30.5 knots as well improving stability and seaworthiness along the way. The hull, thus, used new shapes, better refined, the bow shape was also modified and diverged from the Chidori-class. To increase the hull ration, the hull was made 6.5 meters longer making it a slightly beamier hull as well.
The final design was officially displacing 840 tons standard but 960 tons fully loaded, and it up went to 1,000 tonnes unofficially. The final overall lenght was thus of 88.5 m (290 ft 4 in) versus 85 meters (278 ft 10 in) at the waterline, for a beam of 8.18 m (26 ft 10 in).

The bridge on the Chidori class had a rounded base, two level high even like the “special type”. Of course it was completely cut down and lightened, as the masts in the final version, and the next Otori class had same two-story structure as the remodeled Chidori, but the compass bridge canopy had rigid wall instead canvas. The Otori also gad a new 3-meter rangefinder installed on top, versus the Chidori’s 2-meter rangefinder. The wave breaker of the Chidori-class, forward of the compass bridge was omitted in the design. However during their initial campaign in China, bulletproof panels were installed around the compass bridge.

Next came the short tripod foremast supporting a spotting top and same raked, capped, funnel plus a mushroom cover at its base. Behind was the AA gun platform, unchnanged, a single triple torpedo tubes bank on deck, still 533mm or 21-in Type 96 or 6th year type, but no reloads underneath the funnel. Next came the quartedeck house and short aft tripod mast. It was obvious the initially planned turreted armament needed to be revised, down to three mounts with weazther shields basically, offering no protection against anything but the rain. The kept its two massive paravanes, however it seems their minlaying gear was removed, and they had a single Type 94 depth charge launcher for ASW work. The crew amounted to 129, versus 113 men on the Chidori, with four rescue boats close to the funnels, two whalers and two pinnaces.

Powerplant

IJN Hayabusa on the Yangtze in August 1937, ONI.

The IJN completely revised the design to regain 30 knots for fleet work and the hull was lenghtened to accomodate more powerful engines, two Kampoin impulse turbines. The Kampon boilers were the same as the Chidori-class initially, but they were equipped with an air preheater, and used high-temperature and high-pressure steam at 30 kg/cm² for 350°C, the same as the Chidori-class. The Kanmoto (Kampon) type turbines were composed each of three stages: High, medium, and low-pressure, compared to the Chidori-class’s two-stage system, offering more flexibility and increasing the output to 19,000 horsepower, compared to 11,000 on the Chidoris, a remarkable improvement. This new tupe of turbine was later adopted for the Matsu-class destroyers as well. The previous Chidori class engine room was divided into two halves by an irregular longitudinal bulkhead, each with a single turbine but the Otori class had two turbines in a single engine room, and the generator room aft of it, in a more conventional configuration.
Based on 150 tons fuel oil the range was estimated 4000 nautical miles (7,400 km) at 14 knots.

Armament

The Otori-class were rearmed in a more sensible way compared to the rebuilt Chidori, with a main battery of three single 12 cm/45 3rd Year Type naval guns able to elevate to to 55 degrees for anti-aircraft escort, and a torpedo mount now triple, plus a single Type 94 depth charge launcher aft. The anti-aircraft suite by 1936 standard was quite weak however as it consisted in a single license-built Vickers 40 mm or 2 pounder “pom pom”. The loading practice and saluting gun located on the forecastle deck on the Chidori, was moved to the aft deck. This was considerably revised in wartime (see below).

12.7 cm/45 3rd Year Type naval gun

The Otori class guns were the same as the refitted Chidori-class, three 12cm guns. But they had the new Type 11, 12cm gun (commonly known as the M-type gun) featuring an elevation up to 55 degrees, the “G-type” of the Chidori in comparisin elevated ti 33 degrees and were design to cover landing operations, not AA escort, back in 1933 when the plans were approved.
Rounds: 23 kg (51 lb) HE, illumination, incendiary shrapnel (sankaidan) for AA use, flat-nosed ASW (1943).
1945: HE developed with added charge for 23,025 metres (25,180 yd).
Propellant: 7.7 kg (17 lb) 30 DC.
Muzzle velocity:
-Common Type 0 HE 23 kg (51 lb)/1.88 kg (4.1 lb): 910–915 m/s (2,986–3,002 ft/s)
-Common Type 1 HE 23 kg (51 lb)/1.88 kg (4.1 lb): 910–915 m/s (2,986–3,002 ft/s)
-Illumination 23 kg (51 lb): 750 m/s (2,500 ft/s)
-ASW 20.9 kg (46 lb)/4 kg (8.8 lb): 250 m/s (820 ft/s)
-HE 1945 LG type 27.9 kg (62 lb)/2.2 kg (4.9 lb): 910–915 m/s (2,986–3,002 ft/s)

40 mm/62 “BI” Type 91

Vickers licenced 2-pdr HA (40 mm). Installed on the platform aft of the funnels in most sources. Wether it was kept after trials is subject to debate. Here are its specs:
Gun Weight 619.5 lbs. (281 kg) including cooling water, oa lenght 98.5 in (2.502 m), barrel 62 in (1.575 m).
Round 2.95 lbs. (1.34 kg) HE 11.995 in (30.47 cm). Muzzle Velocity 1,969 fps (600 mps).
Rate Of Fire 200 rpm cyclical, 60-100 rpm practical. Max ceiling 85° 13,110 feet (4,000 m).
Needless to say it was woefully inadequate.

13.2 mm Type 93 heavy machine gun

Part of later modifications: Barrel Lenght 140 cm (55 in) total, 988 millimeters (38.9 in) barrel alone for a mass of 42 kgs (93 lb) empty.
Shell: 13.2×99mm Hotchkiss 13.2 mm. Gas-operated fully automatic +85° elevation, 450 rpm max, effective range 1,000 meters (3,300 ft).
Feed system: Classic box magazine holding 30 rounds, spiderweb anti-aircraft iron sight.

Type 93 Triple 533mm Torpedo Tubes

The torpedo armament now comprised the newly developed Type 94 53 cm triple tube launcher with a mantlet to protect the operator from small arms and shrapnel. There were no spare torpedoes, and the ships were intially equipped with either the Type 6 or Type 92 torpedoes. The Japanese source says “Type 89” but there is no such a thing.

Type 6 Torpedo

1917 mass produced torpedo initially planned for battlecruisers and battleships of the “8-8-8” plan, later cancelled with the Washington treaty. Standard 53 cm torpedo for new cruisers and destroyers when metric was used also for these models.
⚙ specifications Type 6
Weight 3,157 lbs. (1,432 kg), Dimensions269 in (6.84 m).
Propulsion: Kerosene-air wet-heater for 7,000 m/35, 10,000m/32, 15,000m/26 knots.
Warhead 448 lbs. (203 kg) Shimose, straight course model.
Likely two spare torpedoes were carried either side of the amidship structure. The twin mount light shield somewhat protected the operator and its dahsboard.

Type 92 Torpedo

Technically, this was submarine model developed in 1932 and in service by 1934, weighting 3,792 lbs. (1,720 kg) for 281 in (7.150 m) in lenght, a negative Buoyancy of 551 lbs. (300 kg) and 661 lbs. warhead (300 kg) Type 97. It reached 7,650 yards (7,000 m) at 28-30 knots thanks to lead-acid electric batteries.

Depth Charges

The depth charge armament and minesweeping equipment on the aft deck were initially kept as for the Chidori-class, but after completion, the depth charge projectors were changed from two broadside K-type guns to one Type 94 depth charge projector still with two broadside Y-type guns. The number of depth charge was increased from four (Chidori class) to six ready to launch wirh a reserve of 18 total, but later in wartime the minesweeping equipment was removed, depth charge launchers and racks were added, increasing the number to 48.
Standard Type 94:

Profile from pinterest, Chidori class after modifications to compare.

Profile from pinterest, Kasasagi as built.

Otori class profiles and appearance from 1937 to 1944. Ebay, pit-road 1:700 kit.

Modifications

Interwar

The AA defense was ludicrously inadequate after completion, with a licenced 40/62 HI 91-shiki that basically was a WWI anti-aircraft guns. Aicraft speed more than doubled in between. It was planned to add a single twin mount with 25mm machine gun eve completion but shortages prevented this. IJN Hato was equipped with a twin 25mm at the time of completion or shortly thereafter however. The next class in 1937 was planned that way also. In 1938, another could have been equipped the same, but it’s not formal.

Wartime Changes

25mm and 13mm Machine Guns were added on all ships as well as radars, in changing configurations with 25mm Machine Gun in triple, dual and single Mounts, No.13 Detector.

In 1942 all lost the aftermost 120mm/45 main gun and 40mm/62 for two twin 25mm/60 Type 96 AA guns and two DCT for 48 depht charges. Indeed the removal of the aft No. 3 main gun and 40mm machine gun was to spare weight, allowing to install the 25mm machine gun mounts in front of the bridge and on the aft deckhouse. Later this wa sported to three 25mm twin machine guns. Two 25mm single machine guns were also installed on the forecastle deck, three on the aft deck, for a total of five. IJN Kiji and others also obtained six Type 81 depth charge projectors, and one Type 94 depth charge projector, one Type 93 sonar and a Type 94 sonar with hull radome.

Typically by 1944, a twin 25mm/60 Type 96 was completed by five 25mm/60 of the same and a Type 3 1-go radar. IJN Hiyodori by August 1944 had two 12 cm (4.7 in)/45 11th Year Type guns, eleven Type 96 25 mm (0.98 in) AA guns still its triple Type 94 Torpedo tubes with Type 6 torpedoes and 48 × depth charges with the changes described above. Displacement was now 1043 tons. A far cry to the 500 tonnes of the 1933 project…

Type 3 Radar model 1

A common model (1000+ built from 1943), the ship-based Type 3 was a multi-purpose portable early warning 110 kg radar presenting a dipole array with mat type reflector, 2 m for 10 kW, 10 Pulse length (μS), 500 Hz PRF, range 50 km for a single aircraft and 100 km a formation.

Type 93 Sonar

Type 93 Model 3 sonar was a derivative of Model 1, which had been used on destroyers since 1933. It used a retractable quartz projector for both transmission and reception and had a nonretractable sound dome measuring 1.9m by 0.65m (6’3″ by 2’2″).

Otori class Career

IJN Kasasagi on the Yangtze, 1939-1940

After completion, the eight ships were organized into the 1st and 11th Torpedo Divisions. They were considered very useful for operations on the Yangtze River due to their shallow draft, maneuverability and still powerful guns. For this reason, each ship obtained a riverine water filtration system (and later armour panels to deal with small arms fire from shore). They were used in China to support landings in the Yangtze, taking part in many upriver Operations and minesweeping some area. In the Pacific War, they supported the Hong Kong and Philippines invasions and they were deparated and assigned to various base units, engaged in convoy escort and patrol.

IJN Ōtori (鴻 stork) was laid down at Maizuru Naval Arsenal on 8 November 1934, launched on 25 April 1935 and completed on 10 October 1936. She took part in the Chinese Campaign, as seen above, taking part in landings and patrols in the Yangtze from 1937 to 1941. Initially she was assigned to 1st Torpedo Boat Division, Hainan Guard District and on 7 December 1941 she left Samah, to patrol the Hainan-area. On 10 February 1942 her unit was deactivated so she was reassigned directly to Hainan Guard District. On 14-16 February she went to Subic Bay for the Manila blockade. 5-17 April saw her in Hong Kong for a drydoc refit. On 21 April she returned to Samah and resumed her Hainan area patrols. On 16-23 September she sailed to Takao and theno Hong Kong for another refit. From 26 September to 7 October she was in convoy escort from Hong Kong to Palau.
On 12-18 October this was on the Palau-Rabaul,Lae-Buna route.

21-22 November saw her in a fast supply transport run to Lae, but she was near-missed in an air attack, not serious damage. On 23 November she entered Rabaul for repairs.
On 5 December she departed for escort duties from there, and on 8 January 1943 covered the transport that carried construction units to Kolombangara in the Solomons.
On 1 April she was reassigned to 2nd Surface Escort Division, Fourth Fleet and on the 5-8th she sailed to Truk, her new base, for a 20-29 April convoy escort to Yokosuka.
On 3-21 May she escorted convoys from Yokosuka to Truk and back and likely had a refit and rearmament there. 7 June saw her leaving Yokosuka for a Truk-Rabaul convoy escort mission and on 26 July-3 August, Convoy 2262 Rabaul-Saipan via Truk. On 17 August she was sent to Maizuru for another refit until 19 September, completed at Yokosuka.

From 26 September to 5 October she escorted convoy from Yokosuka to Truk and until 20 October from Truk to Saipan and back, then until 20 November, Truk-Yokosuka and back. On 15 November she was reassihned with the 2nd Surface Escort Division under direct control of the General Escort Command. From 27 November to 14 December she wa sin escort from from Truk to Rabaul and back and on 10-15 January 1944, Truk-Rabaul, then Rabaul-Truk via Mortlock Island. On 5 February she was back at Yokosuka for a refit. In February this was a Yokosuka-Saipan mission, then Truk-Rabaul and back home on 11 March. From the 22th to 10 April she escorted the troop convoy Matsu No.3 to Saipan and back.
On 4-14 May this was Convoy 3503 to Saipan and on 17-24 May Convoy 4517 back to Yokosuka, then on 30 May-7 June Convoy 3530 Yokosuka-Saipan. On 10-12 June she was underwya from Saipan with a convoy to Yokosuka when the latter was located and attack by TF 58, 180 miles northwest of Saipan. She was sank by TBF Avengers and/or Heldivers, stricken 18 Jult 1944.

Hiyodori (鵯 brown-eared bulbul) was Ordered in the 1934 Fiscal Year, laid down at Ishikawajima Shipyards on 26 November 1934, launched on 25 October 1935 and completed on 20 December 1936. She was first assigned to the 15th Escort Squadron, Second China Expeditionary Fleet after completion, later taking part in the Second Sino-Japanese War. In the Second World War she operated with the Hong Kong Invasion Force. Next, Hiyodori patrolled the Chinese coast from December 1941 to August 1942. Meanwhile, the 15th Escort Squadron was deactivated and she was transferred under direct command of the Second Chinese Expeditionary Fleet, spending the rest of the war in escort convoys across the Pacific. She was the first to claim a kill, On 16 February 1943, with the submarine chaser No. 18, detecting and sinking USS Amberjack. While escorting a convoy from Manila to Brunei by late October 1944, she assisted IJN Naganami by inspecting the wrecked USS Darter on 24 October 1944. On 17 November 1944 while in covoy she was spotted and as sunk by USS Gunnel, 140 miles (230 km) east northeast of Cape Tourane, off Indochina.

IJN Hayabusa (隼 peregrine falcon) was laid down at Yokohama Dock Co. on 19 December 1934, launched on 28 October 1935 and completed on 7 December 1936. After Chinese operations (see above) until 1941, she was assigned like her sisters to the 1st Torpedo Boat Division, Hainan Guard District. On 11 December 1941 she escorted a convoy on Samah-Keelung and from 10 February 1942 under direct control of the Hainan Guard District. On the 14-16th she sailed to Subic Bay, Manila blockade and on 4 Apri was drydocked in Mako for refit. On 10 April she joined the 1st Surface Escort Division, Southwest Area Fleet and her escort routes were Mako-Lingayen Gulf and froml there to Tokuyama, Kure-Manila in June, Kure-Mako in July, Mako-Sasebo, refit, Sasebo-Mako-Sasebo in August-September, refit, Cape St. Jacques, Singapore and overhaul modernization at Mako from 20 January to 5 February 1943. In February-March, Shanghai-Palau, Palau-Takao and until late April Takao-Saigon, Manila-Moji. In May Moji-Takao, Takao-Maizuru (refit), in June-July Maizuru-Manila and until September Manila-Balikpapan-Palau-Manila, then Manila-Moji and until 10 October Moji-Takao-Manila. From 1st October she was assigned to the 3rd Southern Expeditionary Fleet, ezcorting convoys from Manila via Cebu to the Halmahera Is., Kau-Manila (via Davao), Manila-Kau-Manila in Nov-December 1943. In January 1944 this was Manila-Tarakan-Manila, and until 5 February to Zamboanga and Balikpapan in March, Kau in April, Bacolod, Iloilo Island. On 24 September she was cornered and sank by TF 38′ aviation, her convoy rampaged south of Mindoro, 110 miles off Manila. She was stricken on 10 December 1944.

Kasasagi (鵲 magpie) was laid down at Ōsaka Iron Works on 4 March 1935, launched on 18 October and completed on 15 January 1937. She saw action in China, see above, and was assigned to 15th Escort Squadron, Second China Expeditionary Fleet. In December 1941 she departed Mako to join the Hong Kong invasion force, then the 2nd Malaya invasion force. In 15 January 1942 she left Hong Kong, for Formosa and was refitted at HK in April. Under direct command of the Second China Expeditionary Fleet she became flagship on 14-22 May, refitted on 19-23 September and until late December escorted convoys from Hong Kong to Palau and back or patorlling the Amoy-area patrol/escort duties. In February 1943 she was grounded near the mouth of Kwangchow River, repaired until 25 March and returned patorlling the Amoy-area. In June she joined the 24th Special Base Force, 2nd Southern Expeditionary Fleet, escorting convoys to Surabaya and then Ambon in June, Western New Guinea in july, Saumlaki (Moluccas) in August, Kau (Halmahera), Babo (Western New Guinea) or Ambon-Waru (Ceram), Saumlaki and back, then Ambon-Kaimana (Western New Guinea), Ambon-Kendari and back in september. She was sunk while escorting HOKURIKU MARU, torpedoed by USS BLUEFISH (SS-222) on the 27th, 25 miles south of Flores Sea, stricken 1st December 1943. The first of her class lost in action.

Kiji (雉 pheasant) was the first of the second batch, built still slowly at Mitsui Engineering & Shipbuilding, Tamano, 24 October 1935 when her keel was laid down, but launched only by 26 January 1937, and completed on 31 July. She was in the 11th Torpedo Boat Division, 3rd China Expeditionary Fleet until Pearl harbor, was part of the Hong Kong attack force, and on 15-16 January 1942 Hong Kong-Mako, then Mako-Camranh Bay (Indochina) to Hong Kong, from there to Subic Bay in Febriary for the Manila blockade operations and in March the San Jose (Mindoro) operations, Cebu Island, Tsingtao Area Special Base Force in April, Panay Island operations, Cotabato (Mindanao) operations and in May a convoy Manila-Tsingtao in June she returned to Kure for refit until 2 July and returned to Tsingtao, docked there in January 1943 and abck to Kure, joining in January the 24th Special Base Force, 2nd Southern Expeditionary Fleet, and was sent to Ambon in February for escort missions to the Saumlaki (Moluccas) with troops on board, then to Kupang (Timor), Ambon-Dobo Island (Arafura Sea) and Western New Guinea and on 14 April she was air attacked in a transport run to Saumlaki (strafing damage), repaired at Surabaya for repairs.

She returned in the Saumlaki area and was refitted between 23 August and 22 September in Surabaya, in convoy on the Ambon-Tual Island (Banda Sea). On 30 November she joined the 4th Southern Expeditionary Fleet and retuned to Western New Guinea with a refit at Surabaya. Until 2 May she escorted a convoy from Surabaya to Ambon and Western New Guinea. On 20 May she joined the 2nd Southern Expeditionary Fleet, and was damaged in an air raid on 3 June near Manokwari. On 20 June sje joined the 26th Special Base Force, same unit. After a refit at Surabaya on 10 September she carried personnel and escorted a convoy between Surabaya, Makassar and Ambon and survbived the war. In August 1945 she surrendered at Surabaya, stricken on 20 February 1946, used as repatriation ship and on 3 October 1947, became a Soviet war reparation.

Kari (雁 wild goose) was ordered from Yokohama Dock Co. on a revised design, laid down on 11 May 1936, launched on 20 January 1937 and completed on 20 September 1937. During her Chinese campaign she was in the 11th Torpedo Boat Division, 3rd China Expeditionary Fleet and in WW2, took part on 8-30 December 1941 to the Hong Kong attack force. on 16 January 1942 she was in Mako and escorted convoy to Singora, Sasebo in February, reassigned to 12th Special Base Force, 1st Southern Expeditionary Fleet, in escort from Sasebo to Singapore, from Singapore to Rangoon, refitted in Singapore 23 June-1 July, then in escort to Rangoon, Penang-Andaman Islands, Mergui, Port Blair-Sabang, damaged by air attack on 30 November in the Andaman Islands. On 7-18 December she was repaired in Singapore and departed in January 1943 for Rangoon, and Sabang-Andamans, air attacked while in rangoon on 1 February, repaired in Penang and Singapore and in late April she was back in the Andamans before another refit in Singapore on 18-29 September 1943.
On 3 October 1943 she returned to the Sabang-Andamans-Penang route and struck a mine on 24 February 1944 in the Malacca Strait, north of Sabang, but survived, was repaired in Singapore from 29 February to 17 April. She patrolled off Borneo and in August returned to the Andamans-area, then from November, the Saigon-area and by January 1945, the Singapore-area. On 4 April she left Surabaya, escorting ISUZU to Timor and on 7 April she assisted her after she was torpedoed, took survivors. On 16 July she was herself torpedoed by USS BAYA (SS-318) on the route from Surabaya to Ambon, 220 miles of Makassar stricken on 30 September 1945.

Sagi (鷺 snowy heron) was ordered from Harima Shipyards oand laid down on 20 May 1936, launched on 30 January 1937 and completed on 31 July 1937. She was assigned directly to 5th Fleet in 1940 and by 26-28 November 1941 she left Yokosuka for Akkeshi and by December she wa sin the Ominato-area then in January 1942 in Chichi-jima, then Yokosuka, and Yokosuka to Ominato, Akkeshi-area before a refit at Yokosuka in February, back to Ominato. On 10 April she was reassigned to 1st Surface Escort Division, Southwest Area Fleet and operated on the Moji-Mako-Manila convoy route until October and a refit at Kure 2-12 November. In December she was on the Mako-Saigon-Singapore route and had another refit in Kure by May 1943, then resumed the Moji-Takao route, Manila-Palau in july, torpedoed on 31 August by USS SEAWOLF (SS-197) while in East China Seabut she survived and limped back to Kure. After repairs she was on 5 September reassigned to the Kure Naval District. From 16 September to 12 October she was on the Saeki-Palau-Saeki route, as well as in November, and by January 1944 back in Kure for drydock modernization and refit, and back to escort in February-March Kagoshima-Keelung-Takao-Palau-Takao, reassigned on 10 April to the 1st Surface Escort Division, General Escort Command and escorting convoy to Miri in Borneo and back. On 23 May she was refitted at Saeki, and in June was on the Moji-Miri route util the fall of 1944, also Shanghai-Manila, Manila-Takao but on 4-8 November while escorting convoy to Manila she was torpedoed by USS GUNNEL (SS- 253) off Cape Bolinao, stricken on 10 January 1945.

IJN Hato (鳩 dove) was laid down at Ishikawajima Shipyards on 28 May 1936, launched on 25 January 1937 and completed on 7 August 1937. She was later assigned directly to 5th Fleet for the Chinese campaign, and by 26-28 November 1941 she was sent to Akkeshi. On 6-8 January 1942 she was on the Akkeshi-Yokosuka route, reassigned to Kure Naval District and in February-March escorted convoys on the Yokosuka-Truk-Kure route, Yokosuka-Rabaul and back in April, Yokosuka-Kwajalein-Rabaul and in May Rabaul-Kure. Until 4 June she was refitted there and sailed to the Western Inland Sea. In September-October and until December she was on the Saeki-Saipan-Saeki route. In January-February 1943 she wa son the Saeki-Palau-Saeki route (refit in Kure February) and from April to October, same as before several times. Until 8 November she was in refit at Kure, and escorting convoys to Palau thrice, then Moji-Singapore-Kure and in April she was reassigned to 1st Surface Escort Division, General Escort Command.

In May she was in convoy from Moji via Manila to Miri, and Manila, the Manila to Kure in June, Moji-Manila, Manila-Singapore and back in July-August, Manila-Takao, a refit, and until 11 September Takao-Manila-Manila, then Takao-Moji, Moji-Takao-Hong Kong and in October after leaving Hong Kong she was in an air attack by TF 38, sunk 130 miles off Hong Kong, stricken on 10 December 1944.

Read More/Src

Books

John Gardiner, Conway’s all the world’s fighting ships 1922-47.
Chamberlain, Basil Hall. Things Japanese: Being Notes On Various Subjects Connected With Japan, For The Use Of Travelers And Others. Tuttle. 1905.
Samuels, Richard J. “Rich Nation, Strong Army”: National Security and the Technological Transformation of Japan. Cornell University Press.

Links

navypedia.org
ja.wikipedia.org
combinedfleet.com TROM IJN TBs
Colorization by Irootoko Jr.
nippon.zaidan.info shipyards
Pacific war encyclopedia
fh-giessen.de
combinedfleet.com/Fourth-Fleet-Incident
en.wikipedia.org
navweaps.com
historyofwar.org
The Pacific War Online Encyclopedia, TBs
usni.org Tactical Considerations Involved in the Design of the Torpedo-Boat By Lieut. A. P. Niblack, U.S. Navy 1990

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