I was reading about the recent collision between the USS Hartford sub, and USS New Orleans; apparently the sub - which was at periscope depth - rolled 82 degrees onto her side, causing serious injury to 15 crewmen.

This got me wondering as to what would have happened if she'd rolled more than 90 degrees...what then? Would she re-right herself or would the sub have simply hung there, upside down?

I imagine it would be extremely hard to keep a sub upside down as you could gradually empty one ballast tank whilst filling the other to right her?

If you liked that story, you will love this one:

On 11 February 1969 the modified Balao-class submarine USS Chopper lost her electrical load at 150 feet while moving at 10 knots with a slight down bubble. She immediately nosed down to 45 degrees and began to plunge, her down angle steadily increasing to vertical.

Even with her motors driving full back she still knifed downwards, her bow section edging past 1,000 feet. With everyone inside literally dangling from whatever handhold could be found, the Chopper began to climb vertically and then her trim rapidly leveled out before it shifted upwards to near vertical again!

Now the boat arrowed up to break the surface clear back to the aft edge of the sail before the hull slapped down onto the water and plunged back down below 200 feet before she was brought to the surface on level trim. The total event spanned just two minutes.

The structural damage was extensive and months later the Chopper was decommissioned.

This incident may explain how a few submarines simply disappeared as "operational losses" at sea as well.

--Karl

That is sickening to even think about... I would truly never want to experience such an event.

Not too sure about the more 'modern' types of submarine.
but as I understand it, the more dated classes had openings in the bottom of their ballast tanks (apart from trim tanks), so that during a 'blow' compressed air forced into the top of the tank will just push the water out through the bottom.
The reverse consisted of opening (kingston?) valves at the top of the tank to let the air out - and water into the bottom - There was no way to close the openings in the tank bottoms, so a sub rolling upside down would, unless VERY quickly righted, fill the tanks with water with no way of getting it out (even using all the compressed air on board)
Teardrop hulled subs (I believe) have their ballast tanks placed fore and aft of the pressure hull underneath the outer casing (which floods with water as the boat dives).
Hope to have helped.
Tom

Some ships (not subs) are "self-rightening" that is they will come up again even if turned upside down without the crew doing anything. German SAR vehicles like the Georg Breusing class can do that (and sadly Bermpohl tested it in action on 23. Feb 1967 with all four crew swamped over board since they where on deck for a rescue operation)

As a former EM1(SS) (Electrician's Mate 1st class, Submarine Warfare), I can tell you, it was really ugly on many levels, but not irretrievable. The ship itself would've righted without action; the main battery alone weighs like 200 tons. The reactor and the primary shield tank are on the bottom of the ship, and obviously hard mounted there. A lot of really heavy stuff is in the lower 1/2 to 1/3 of the ship (diesel, torpedoes, etc). I am not saying that there are no engineering issues raised by flipping a boat on her side. But I equally cannot go into the exact issues on a public forum. But the ship would not stay upside down. Would NOT want to be inside for any amount of money.

@MBR your German SAR boats are like the 44 foot US Coast Guard boats that I was an engineer on back in the 70's. They are specifically designed to be self-righting in case of a knock down. When I was in training to become an engineman I saw some films taken during coxin training in Oregon. The boats would go thru the surf at the mouth of the Colorado River and be deliberately rolled over. The film was....exciting, and scary, to say the least. I think you can find it on You Tube today.
And as far as the subs are concerned, I think I'll stick to surface warfare thank you very much!
Later

During a Tonkin Gulf deployment my ship, USS BAINBRIDGE (DLGN-25) had a scheduled 2-day ASW exercise with a SSN and a GUPPY boat in the South China Sea on our way back to Subic Bay. At the end of the second day (to make a very long story very short) we collided with the GUPPY (USS BLACKFIN). I was on liberty when we got back to Subic Bay and ran into a Quartermaster from the sub. He said the collision rolled them onto their beam ends (i.e., laid them over on their side)--and that it was NOT a pleasant experience!