Reassessing
The
Combat Performance
Of The
Japanese Midget Submarine Force
At
Pearl Harbor
A Technical Assessment
I-22 Tou
I-16 Tou
Mother Submarine & Midget Release at Local Time
(0626 Sunrise)
Bearing & Range from Pearl Harbor’s
Buoy marking the channel entrance.
I-16 and I-16 tou (A) 0042 212 Degrees at 7 Nautical Miles
I-22 and I-22 tou (B) 0116 171 Degrees at 9 Nautical Miles
I-18 and I-18 tou (E) 0215 150 Degrees at 12.6 Nautical Miles
I-20 and I-20 tou (D) 0257 151 Degrees at 5.6 Nautical Miles
I-24 and I-24 tou (C) 0333 202 Degrees at 10.5 Nautical Miles
Release Sequence
I-16 Tou
I-22 Tou
I-18 Tou
I-20 TouI-24 Tou
0000 15 30 45 0100 15 30 45 0200 15 30 45 0300 15 30 45 0400 15 30 45 0500 15 30 45 0600 15 30 45 0700 15 30
I-16 tou ^----------------------------*-->
0042 0215 30
I-22 tou ^----------------------------------*--->
0116 0317 35
I-18 tou ^---------------------------------------------*---->
0215 0455 12
I-20 tou ^----------------- --*---->
0257 0409 24
I-24 tou ^ Defective Gyro----------------------------X------------------>
0333 0613
USS Condor & USS Crossbill []--------------------------{}----------------------------+
0200 0350 0525
USS Antares -------------------------->
USS Ward -------------------------------------------------------------------------------------------------------------------{}--X---------->
0630 45
Submarine Net Gates Open 0200* 0458----------------------------------------->
^ = Release Times
* = Estimated Time to Harbor Entrance Channel Buoy @ 5 Knots
> = Estimated Time to Harbor Entrance Channel Buoy @ 4 Knots
X - I-24 tou Runs Aground On North Shore
[] - USS Condor On Station For Mine Sweeping Ops
{} - ~ Time That USS Ward Sights One Of The Midgets
X - USS Ward Open Fires on One Of The Midgets
* - Exact Time For Nets Opening Unknown. However, At 0200 The Minesweepers Passed Through
MIDGET SUBMARINE MOVEMENT / USN EVENT AND CONTACT TIMELINE
Midget Attack Geometry
Midget Attack Geometry
The Initial Study - 1993/94
NPS Asked, “Is It A Sub”?
Team Conducted Two Interrelated Analyses:1 - Imagery Intelligence:
Look for Observables
Establish Timeline
2 - Photogrammetric: Conduct Critical MeasurementsCorrelate Object to Geographic Location
Determine Object’s Dimensions
1993-94
Object
Roster
Tails
Splash
Points
Wave
Propagation
Plume
Torpedo
Tracks
Utility
Boat
Splash
Point?
Aerial Photography 26 November 41
~21.21.34N/157.57.18W
Wave Motion
Entrained Water
Submarine Trim
SUBMARINE TRIM ALTERED
1994 Summary of Analysis:
Team’s Assessment:
Established Operational Timeline
Measurements
Rooster Tails
Wave Propagation
Torpedo Tracks v. Splash Points
Explosion Plume coincides with TT
Report To NPS 6 Dec 1994 - SUBMARINE
Subsequent Analysis - 1998
Forensic AnalysisRoster Tails
Weapon Effects
Entrained Water
Submarine Trim
APPEARANCE DIFFERENT FROM EXPLOSIONS
ENTRAINED WATER FROM COUNTER-ROTATING
PROPELLERS
Weapons Effects 2
Weapons Effect
Cavitation Regions For Underwater Explosions
UNSOLVED HISTORY SERIES COLLABORATION
2002-2003
2000 & Beyond: Correlation Of Additional Data
Translated Official Records
Analyzed Collateral Images
Translation Of Official Records
From Japanese Defense Force Documents*At 2241, December 7 (Local Time)
To I-16 From I-16 tou
“I Succeeded In A Sneak Attack”
At 0051, December 8 (Local Time)
To I-16 From I-16 tou
“Impossible To Navigate”
•As provided by Yoshinori Nakai, Washington Bureau Chief, Manichi Newspapers
•Translated by Yoko Spalding, Quick-Call Decision Interpretation, Inc.
WHAT WE KNOW
Of the Five Submarines:
I-22 Tou 7 Dec 41
I-18 Tou 2005I-20 Tou 1960
I-24 Tou 7 Dec 41
THE BIG QUESTION: WHERE IS I-16 Tou?
JOURNEY PROGRESSION
1993 – Is It A Sub?
1994 – Submitted Findings To The NPS
1998 – Subsequent Analysis Applied
1999 – Submitted Findings To USNI
2000 – Cross Correlation Of Additional Data
2004 - Discovery TV Correlates Assessment
2010 - NOVA’s Portrayal Clarifies Assessment
Where is the Sub?
NOVA Assessment:
• Midget Sub recovered after Disaster
• Wreckage dumped offshore• Photographic Evidence Of Wreck• Crew Scuttled Sub in West Loch
HOWEVER: Appearance Does Not Correlate
Edges not caused by internal explosion
Skin peeled outward