Crossing Paths
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I-16tou Datum

With the I-16tou torpedo firings already being addressed in other articles, it is now time to focus on what I-16tou probably did after the release of its second torpedo. To do this, it was essential to locate I-16tou at the time of his departure from his attack position. The location is taken from the Matsumura photograph. The time is taken from the USS Vestal (AR-4) and USS Ramapo (AO-12) After Action Reports, which state:

(Vestal) "At about 0820 a torpedo was seen to pass astern of the Vestal and it apparently hit the Arizona whose bow extended about 100 feet beyond the Vestal. The Arizona's forward magazine exploded."

(Ramapo) "Emergency SAIL hoisted on Signal Tower. Arizona hit by a torpedo. 0809 Arizona hit by second torpedo. About two minutes later a spurt of flame came out of guns in #2 turret, followed by explosion of forward magazines...."

Here we can see the time is approximated but the event (USS Arizona exploding) is not. Timelines show the USS Arizona (BB-39) exploding at 0810. Even though Ramapo's report is more accurate timewise, Vestal's report is focused more on the arrival of a torpedo than the Arizona destruction. The belief that Arizona had received two torpedo hits has remained controversial since the attack on December 7, 1941. Eyewitness accounts of the first torpedo are based mostly on the fact that a torpedo bomber flew over the stern of Vestal and the bow of Arizona. The flyover did happen but only after two torpedo bombers nearly suffer a mid-air collision while both attempted to torpedo the USS West Virginia (BB-48). After releasing their torpedoes, eyewitnesses observed the right torpedo bomber take evasive action and veer to the right to avoid the mid-air and ended up flying over the bow of Arizona. The second torpedo into the Arizona was observed by multiple eyewitnesses. Did the USS Arizona receive a torpedo hit? Possibly – but if it did, the torpedo did not explode.

A confidential report from the Commandant, Navy Yard, Pearl Harbor, to the Chief of the Bureau of Ships, dated 7 October 1943, in section 5. subparagraph (b) "No evidence of torpedo hits has been found, although the condition of the flat of the bottom forward inboard of the areas searched as described in paragraph 2 (a) is not known. The bottom structure in the forward part of the ship is not accessible from inside and is embedded in the mud outside."

From the CINCPACFLT After Action Report, under Part III Narrative of events, Phase 1 – 0755 – 0825 (Combined Torpedo Plane and Dive Bomber Attacks) (A) Torpedo Planes, Subparagraph 1., while describing the attack "toward the battleships on the South side of Ford Island," states "A recovered unexploded torpedo carried a charge of 1,000 pounds of explosive."

The Nakajima B5N2 Torpedo Bombers (Kate) carried the Type 91 Mod 2 torpedo which had the Type 97 warhead with an explosive charge of 452 lbs equivalent TNT. The I-16tou carried two Type 97 torpedoes with an explosive charge of at least 796 lbs (based on a restricted report from the Inspector of Ordnance in Charge, U.S. Naval Powder Factory, Indian Head, Maryland, dated, June 16, 1942 on "Details of Physical and Chemical Examination of Japanese Warheads" detailing the analysis of the two torpedoes recovered from I-24tou which washed up on Waimanalo Beach near Bellow Field on the east coast of Oahu.

It is here that we have physical proof that I-16tou had been in the Southeast Loch and had launched its torpedoes on Battleship Row. Two items concerning this observation must be noted to the reader:

1. That the initial recovery report of this "unexploded torpedo carried a charge of 1,000 pounds of explosive" has yet to be located.
2. Admiral Bloch's testimony provided to the Roberts Commission, PHA, Part 22, p. 469;
Tuesday, December 30, 1941
General McCoy: Has this attack shown that the Japanese have some new form of torpedo?
Admiral Bloch: A much greater power.
General McCoy: Than the others?
Admiral Bloch: We have recovered some of their torpedoes. The torpedoes themselves from the viewpoint of their mechanism are very antiquated. They had torpedoes in use, the steering gear and so forth, that we were using back in 1905 and 1906. They used Whitehead engines and they had very small air flasks and probably a very short range and at a very slow speed, but they carried a tremendous explosive charge. One torpedo that we recovered from the submarine had a thousand pound explosive charge in it. Now one of these torpedoes would not destroy a battleship or sink it, but put four or five of those torpedoes close alongside and it will sink it. I am trying to tell you just what has happened.

The Japanese research team questioned whether or not the sentence in the CINCPACFLT After Action Report may be referring to the Bloch Testimony and that possibility does exists. But the CINCPACFLT AAR section focused on the attack on Battleship Row and did not refer to "torpedoes recovered" as I-24tou had two intact and the two torpedoes fired by I-22tou on the north side of Ford Island had both exploded. In either case it is up to the reader to believe the evidence presented before them.

As I was conducting a post-mission reconstruction of the I-16tou, it is based on this information that a datum of the I-16tou was established in the Southeast Loch off Battleship Row at a time 0810.

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