did a Google search and found this link
http://www.seawolfproductions.com/Sh...ku_maruweb.htm
If the sketch at the bottom of the page is accurate, that Avenger did a Hell of a job on that ship.
Here is another link with another explanation for the destruction:
http://members.aol.com/HBBolten/Aikoku.htm
"The plane was hit by antiaircraft fire from the ship and crashed into the first hold in front of the bridge, where it exploded. Seconds later, there was a giant explosion, in which the Aikoku Maru vanished. There was an intensive flash, followed by a shockwave and an explosion cloud, that looked like from an atomic detonation."