As I noted earlier this week, the Korean Ministry of Defense has released the detailed report of the international investigation into the Cheonan sinking.  The report is available in English as a three part PDF file.

For today’s post, I am not interested in the investigation team’s conclusion as to what sunk the Cheonan.  Rather, I am interested in what did not sink the Cheonan.  While the investigators naturally included other possible reasons for the Cheonan sinking as part of their scientific investigation, the results of those parts of their investigation serve to help debunk some of the alternative theories that have been floated about. 

There are more technical sections of each part the report, but I am going to stick with segments of the “visual inspection” sections.  Feel free to dig deeper and see the figures noted in the quotes.

Alternative 1:  The Cheonan ran aground

From page 55 of the report (page 28 of the first PDF file):

 

No scratch or cutting consistent with a grounding was found on ROKS Cheonan on the bottom of the hull along the longitudinal direction. In addition, the sonar dome, and propellers located on the very bottom of the ship, were observed with no grounding damages as displayed in  (Figure II-1-1) and (Figure II-1-2).  Furthermore, two types of hull deformations, impossible to occur in a grounding event, were observed.

 

 

Alternative 2:  The Cheonan collided with another ship (an American submarine, if your are conspiracy-minded)

Page 61:

 

When observing the fracture shape of ROKS Cheonan on the sides (see <Figure II-1-9>), there are no apparent fractures and debris that resemble a bow of an incoming ship. Furthermore,the overall fracture status indicates a massive upward force originated from the bottom. Additionally, the dishing effect apparent on the bottom plate of the ship, shown in  <Figure II-1-3>, is a deformation that cannot occur through a collision but can be seen as a result of intense shock pressure from underwater.

Alternative 3:  The Cheonan was detroyed in an explosion in one of its ammunition magazines

Page 67:

 

Investigation on the exterior of the stern and the bow, where 40 and 76mm magazines are located, showed that no upper iron plates of the waterline had undergone bending effects.  In addition, the magazines showed no trace of internal damages, and there was no deformation in an outwardly direction on the magazine bulkhead and no damages resulting from fragments. Furthermore, no leftover fragments were found. In addition, the salvaged ammunition cases were only bent as a result of the waterpressure without traces of an explosion (See ).

Alternative 4:  The Cheonan’s fuel supply exploded

Page 68:

 

Damage on the hull is not at the fuel tank and is not consisten with that of a fuel tank explosion.  After recovering the hull, it was confirmed that the two fuel tanks behind the diesel engine room and in front of the gas turbine room were not damaged. The fuel, mixed with seawater, remained in a relatively good condition and was recovered and disposed of. The side plating and bottom hull were intact. In other words, there was no trace of a fuel tank explosion.

Alternative 5:  One of the Cheonan’s engines exploded

Page 70:

The front bulkhead of diesel engine room was damaged towards the stern direction.  The gear box and shafts were found bent upwards and toward the starboard, with the starboard shaft bent more than the port. The two diesel engines did not show any damage that would result from an internal explosion and remained in a relatively good condition.

 

Alternative 6:  The Cheonan’s gas turbine exploded

Page 74:

The starboard shell plating and upper deck were blown off in an outward direction from the gas turbine room by explosion. An inward deformation of the hull occurred and no traces of fire, soot or damage holes due to fragmentation were found.

The report similarly dismisses the possibility of the Cheonan having been hit by a surface attack such as a missile.

The possibility that the Cheonan was sunk by a mine was also addressed, which will be the subject of my next post.

 

The report comes in at hefty 313 pages of dense prose and technical jargon.  However, it is richly blessed with charts, pictures and graphics for visually oriented people such as yours truly.  In any case, it is worth a read for those interested in understanding what happened to the Cheonan last spring.  However, this summery should be enough to deal with some of the wilder claims and doubts being thrown out there.