New submarine movie: TORPEDO U-235

[u crank]

Originally Posted by Onkel Neal

Another underwater battle between two subs. Hey, in WWII, were any submerged subs
able to torpedo another submerged sub, solely by passive sonar? And I don't mean one was surfaced
and one was at PD, I mean 50m down, no visual bearing, range by sound alone?

Yep. U-864 sunk by HMS Venturer. February 9 1945.

https://en.wikipedia.org/wiki/German_submarine_U-864

[Onkel Neal]

Originally Posted by u crank

Yep. U-864 sunk by HMS Venturer. February 9 1945.

https://en.wikipedia.org/wiki/German_submarine_U-864

Ah, yes they were submerged but both were using snorkels/scopes and therefore their surface position was marked.

The British submarine HMS Venturer was sent from the British submarine base at Lerwick. After German radio transmissions regarding U-864 were decrypted, Venturer was rerouted to intercept the U-boat. On 6 February, U-864 passed the Fedje area without being detected, but one of her engines began to misfire and she was ordered to return to Bergen. A signal stated that a new escort would be provided her at Hellisøy on 10 February. She made for there, but on 9 February, Venturer heard U-864's diesel engine noise. Venturer was not using active sonar, (ASDIC), to avoid betraying her position and spotted the U-boat's snorkel.

In an unusually long engagement for a submarine and in a situation for which neither crew had been trained, Venturer waited 45 minutes after making contact before going to action stations, waiting in vain for U-864 to surface and thus present an easier target. Upon realizing they were being followed by the British submarine and that their escort had still not arrived, U-864 began zig-zagging. Each submarine risked raising her periscope. After three hours, Venturer fired all four bow torpedo tubes at the U-boat's predicted position, beginning at 12:12 and at 17 second intervals (taking four minutes[citation needed] to reach their target), then dived suddenly to evade any retaliation from his opponent. U-864 heard the torpedoes coming and also dived deeper and turned away to avoid them, managing to avoid the first three but unknowingly steering into the path of the fourth. Imploding, she split in two, sinking with all hands and coming to rest in over 150 m (490 ft) of water, 2 nmi (3.7 km; 2.3 mi) west of Fedje.[6]

In this movie, both subs were deeper than 20m and neither had a snorkel or scope to use as a reference.

But that U-864 does fit the bill.

[Catfish]

As far as i read U 864 was running surfaced when performing the zig zag course, being observed by the english sub alright.
Only when the english sub had fired its 4 torpedos, U 964 dived to evade at greater depth, but ran into the fourth torpedo. So one can hardly speak of a submerged duel?
There is obviously a fault in some report

Also the U 864 carried the aforementioned parts and plans and mercury, but no uranium or such. This was tried in another boat bound for Japan, with the appropriate hull name of U-234.