What would have happened if there had been an explosion in the forward torpedo room? Could the preassure wave have traveled aft though open bulkhead hatches and blow open this hatch, already half opened? Would that wave have decreased enough as to allow crew members in the engine rooms to shut their bulkhead hatches (thus keeping them dry and later imploding, as opposed to the forward section)? Was the lower hatch at the conning tower closed as part of battle stations drill (it would account for it staying dry and imploding)?

Looking at the dogs. I don’t think the actual dogs snapped. I think the entire assemble on the upper and lower right dogs are broken off. The lower left assembly is intact.

(with apologies, I don’t know the correct terminology…)

From pictures, there appears to be two types of hatch loking systems used on these boats. One used heavy “L” or “H” shaped bars running from the locking mechanism to the dogs. The other used heavy rods running from the locking mechanism to the dogs. The rod screwed into a yoke (the heavy bronze casting shown in GRUNNION pics). This yoke is what levered the actual dogs into place.

The upper and lower right dogs, the rods separated from the yokes. We’re looking at the yokes attached to the hatch dogs. The dogs (curved metal latches rough 1.25-1.5 inches across, the thickness between the ears of the yokes and the stainless steel pins) have rolled ioutward and are resting against the hatch, and the snapped off ends of the rods are lying against the inner face of the hatch. Upper dog, the yoke has turned outward and you can see the threaded hole. Lower right, the yoke is sticking straight out, and you can see the snapped off end of the rod. (see open hatch 15/16) Lower left is intact, and you can see the actual curved dog in the accretion (open hatch 5) directly below the hatch gasket.

Or so it appears to me…