The nuclear-powered submarine
The intricate machinery aboard a nuclear-powered submarine is complex: these boats in fact have complicated diving systems consisting of many ballast tanks, trimming tanks, auxiliary tanks, emergency tanks etc.
Many valves (connected with pressure tanks filled with compressed air, which is gathered and stored during the surface cruise) with many backup systems control all of the systems listed above.
During surface cruise the submarine is in a state which is called a positive buoyancy, because air fills the boat’s diving tanks.
When the dive is ordered, the upper vents of the ballast tanks are being opened when the dive is ordered. This causes the tanks to flood with water through the bottom openings. Now the submarine has either neutral or negative buoyancy – it dives and can cruise under the water’s surface.
Does a submarine’s inside diameter get visibly smaller on deep dives?
‘On Thanksgiving Day, 1981, the USS Boston got underway for sea trials after an extended period in the shipyard. After standing watch in the morning, I went to my stateroom to do some paperwork. While I sat there, the boat went down to test depth (the deepest it normally goes) as part of the sea trials test program. When the Thanksgiving lunch meal was ready, a crew member knocked on my stateroom door to invite me to the meal. I walked to the door, turned the handle, and couldn’t open the door.
Test depth testing
‘It was wedged shut. As a result of some of the changes made while we were in the shipyard, as the hull had compressed the deck above my stateroom was unable to shift properly on its “floating” structure, which pressed on and distorted the frame of my stateroom door, wedging the door tight into the door frame.
‘After a brief consultation with the test director (talking to me from the other side of the door), we concluded that the door could be taken apart if I really needed to get out. Otherwise, we’d just wait until the test depth testing was completed and we came back shallow.
‘So, I sat there for a couple of hours. Laughing crew members offered to slide me turkey under the door (which wouldn’t have worked anyway since the door was wedged tight against the deck). As soon as we headed back toward more normal depths, the hull expanded, my door popped free of the door frame, and I was able to leave.’
“Stateroom door repair” went onto the list of work items from sea trials.’
Photo credit: US Navy