Tuesday, May 19, 2015


Many submarines were modified to carry and launch three to six kaitens. The pilots entered the weapons while submerged through a connecting hatch. The ideal scenario would be for the mother sub to launch the weapons 7-8,000 meters from target. He would be on compass heading only and would risk use of the periscope only to acquire the target about 1-1,500 meters out.

The few successful contacts resulted in thunderous destruction but the vast majority of missions led to nothing at all. Kaitens must have missed entirely and ran out of power or were sunk by either enemy or mechanical failures. At any rate the successes did not justify the expenditure of lives.

Regarding the Kaiten carried by I-58 during the patrol, which resulted in the loss of the USS Indianapolis, the following details emerge. I-58 departed Kure on July 16, 1945 and immediately returned to repair Kaiten periscopes. On July 18, Hashimoto once again departed for his station east of the Philippines. 

At 1400 hours, on July 28, I-58 sighted what Hashimoto identified as a tanker and destroyer escort. He launched two Kaiten at this time and claimed two hits. In fact, the cargo ship Wild Hunter, and destroyer Lowry were the targets. Lowry sustained moderate damage from an explosion; the submarine was reported to authorities. Apparently, USS Indianapolis was not informed of this incident (she had departed Guam several hours prior to the attack) although Captain McVay was informed of IJN submarine activity in the area east of the Philippines. After the sinking of USS Indianapolis, Hashimoto proceeded to patrol for targets between Okinawa and Leyte. On the morning of August 10 Hashimoto launched a Kaiten against destroyer escort Johnnie Hutchins and a second against four of her sisters. He escaped upon the surface and claimed to have sunk two destroyers. 

In what would prove to be Hashimoto's last Kaiten launch during the war the USS Oak Hill -- a landing ship, dock -- and destroyer escort Thomas F. Nickel were sighted late in the afternoon of August 12, some 350 miles southeast of Okinawa. Identifying the vessels as a seaplane carrier and destroyer escort, Hashimoto launched his last operational Kaiten. At about 1830 hours Oak Hill sighted a periscope close aboard and maneuvered to evade. Nickel charged in to attack, heard the Kaiten scrape along her port side and watched the craft explode some 2,500 yards away. Hashimoto recorded the explosion and subsequent depth charging which the Nickel had commenced when Oak Hill reported a second periscope in the vicinity. Recording an apparent hit, Hashimoto returned to Japan immediately thereafter." 

My source is "Suicide Squads," by Richard O'Neill (published in 1981).


Used by the IJN in the final stages of WWII, the Kaiten Type 1 was a Type 93 torpedo modified as a one-man suicide weapon, although provisions were made for the pilot to escape before impact. In practice, however, none attempted to escape. With over 400 Kaitens built, only 100 were ever sent on missions, and out of those 100 missions only two succeeded in sinking enemy ships. In the end, the unmodified, unmanned Type 93 torpedo used conventionally was a much more effective weapon. 


Kaiten details

The Finemolds kit of the Kaiten is a Type 1 Kaiten and the Kaiten at Pearl Harbor is definitely one of the larger ones which is the Type 2 or 4, I cannot remember. The Kaiten Type 1 is 14.75 metres long and displaces 8.3 Tons and the Kaiten Type 2/4 is 16.5 metres long and displaces either 18.37 or 18.17 tons per Fukui's book. Also the Kaiten Type 1 had a crew of one as in the plans I have and the Type 2 or 4 had a crew of 2. From the 40 photos I have of the inside and outside Type 1 there is not a great deal inside to detail, so I think there is not much point in doing any interior modeling and sealing it up completely so you cannot see it yourself.

I think there is a bit of confusion here. The midget subs used to attack Pearl Harbour on Dec. 8 (Japan time) 1941 were NOT Kaiten. They were top secret midgit subs, the KOHYOTEKI. They were 2-manned midgit subs capable of carrying and firing two torpedoes. Although their chance of returning to the mother sub was slim, they were NOT suicide weapons.
KAITEN, on the other hand, was essentially a torpedo manned by a pilot(s) to ensure their success on hitting their target. They were used toward the end of the war, and they were indeed suicide weapons. Kaiten was NOT a submarine.

Fine Molds released both the KOHYOTEKI (midget sub) and KAITEN(manned torpedo) in 1/72. Perhaps this too contributed to the confusion here?

There is definitely a Kaiten Type 2 or Kaiten Type 4 at the museum at Pearl Harbor right now on display as of the last time I visited. I never said that a Kaiten of any type was used to attack Pearl Harbor in 1941. The Kaiten type 2 was the type that was being developed in 1944-1945 using the Type 6 engine which used hydrogen perioxide as an oxide for the fuel. When that failed, other efforts were made to convert it to other fuels, this was the Kaiten Type 4 which also was a failure. No Kaiten Type 2 or Type 4 ever reached operational use as they both were still in developement. I have a copy of the large U.S. Navy report from 1946 which covers all this history. The Kaiten now at Pearl Harbor is part of the very long list of submarine material that the "Naval Technical Mission to Japan" reported as brought back to the United States in about November of 1945. I have the complete list of all these items which includes "all" the Kaitens brought to the U.S., plus I have a 8" x 10" photo of the Kaiten at the Submarine Museum(Bowfin) at Pearl Harbor.

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