[Buddahaid]

Originally Posted by Nisgeis

My Theory:

She was making a submerged down the throat attack, fired three torpedoes, then went full rudder and dived. Hatsutaka evaded and closed for an attack on the last position and layed a pattern. Torpedomen got the top two tubes closed and the third was in the process of being closed, when a DC from one of the Hatsutaka's throwers exploded in very close proximity to the hull, as the Lagarto turned hard to get out from under the DD's track. The DC caused the bow planes to jam and also due to the distortion of the pressure hull, a loss of buoyancy. Stern planes were set to full rise to try to regain attitude control, as a full dive was in progress, which accounts for the unusual positioning of the fore and aft dive planes. Possibly the watertight doors would no longer close due to distortion to the pressure hull and bulkheads.

The stern planes are set for dive as I understand it and I'm not convinced the tube inner doors are that weak at that depth, even if a DC exploded close which is not indicated by any damage on the starboard bow. I would believe that with the forward ballast tanks damaged from the port side detonation, she was unable to rise. I saw nothing to prove the people tank was breached and flooded so I don't know why they believe water got in. Subs do not have much buoyancy reserve, like a surface ship, so ruptured ballast tanks are enough.

Anyway that's my take.

EDIT: After reading diving procedures, I see that the stern planes are used for controlling the "bubble" or angle. Diving fast in shallow water you would want to keep close to zero bubble so as to prevent plowing the bow into the seabed. The planes would be as they were found like this.
stern (\).........bow(\)