I saw the show. I really enjoyed it. I think it's a puzzle that none of the glass from the port hole ended up with the piece of cast iron frame on the floor of the sub. This sounds like a weak implosion more than a penetration hit from the outside. But if the hit was on the frame itself it may have pushed the glass away from the sub? I don't see Civil War small arms doing this kind of damage, maybe a swivel cannonade? Great show.

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David Upton