One time I was standing watch as Officer of the Deck, Submerged, when we were acting as the target for another submerged submarine to fire an actual torpedo, minus warhead, at us. We were at an assigned depth, and the torpedo was set to run a fixed depth below our keel. Odax was one of perhaps four submarines that were still authorized to act as target in one of these exercises, for obscure but valid reasons, so we knew the drill. The first time it happened on my watch was memorable. I ran the pre-established route from the operations plan. We went through the Quiet Ship exercise. I heard simultaneously from our sonarman, who told me that the torpedo was running normally, and from the Officer of the Deck of the other submarine, who called on the underwater telephone to tell me that he had fired at us. This torpedo was not an acoustic homing type, so I was free to make noise once it was launched. I made an announcement on the PA system that there was a torpedo in the water, and that anyone who heard it pass under us was to call me on a specific sound-powered internal telephone circuit. The plan was to get everyone who heard it together to try to figure out if the torpedo had run under us or had missed our profile.
It was a very good shot, except that the depth setting was off. The 3000-pound torpedo was travelling at 45 knots when it hit us squarely in the side of the forward engine room.
Forty of the 72 sailors called me to say that they heard the torpedo.