New game: Crash Dive

[PanicEnsues]

Originally Posted by TheCod

Could WW II German subs accurately target convoy ships while below periscope depth?

The Germans had approximately the same tech as Allies in that regard: If they knew the position, heading, and speed of a target, they COULD fire from any depth.

However, given that:

A) they couldn't use their targeting data computers (which used input from the periscope or mounted binoculars for bearing input),
B) if they ship changed course they may not know about it early enough to recalculate, and
C) torpedoes were the most precious, limited commodity to a sub,

neither side seemed willing to risk a miss by firing blind.


For Crash Dive, I tried to apply the same logic. Since you can see the exact position, speed and heading of any ship that's close enough, you can take a shot from any depth, but you can't use the TDC (you have to manually line up the bearing/time lines).

Hope that helps!

-Scott

[Aktungbby]

Originally Posted by PanicEnsues

neither side seemed willing to risk a miss by firing blind.
-Scott

NOT QUITE:

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 ASDIC {active sonar}, 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 Launders decided to make a prediction of U-864's zig-zag, and released a spread of his torpedoes into its predicted course. This manual computation of a firing solution against a three-dimensionally manoeuvring target was the first occasion on which techniques were used and became the basis of modern computer-based torpedo targeting systems. Prior to this attack, no target had been sunk by torpedo where the firing ship had to consider the target's position in three-dimensional terms, where the depth of the target was variable and not a fixed value.
In most torpedo attacks, the target would have been visually acquired; the target's angle relative to the attacker and its bearing would be observed, then arangefinder in the periscope used to establish the distance to the target; from this speed could be derived, and a basic mechanical computer would offset the aiming point for the torpedo. In addition, any torpedo depth had to be set based on target identification. Too deep and the torpedo would pass under the target, too shallow (in this instance) it would miss above. Launders could only estimate the depth of his target. In terms of a challenge, this was far outside what they had trained for, as they tried to manoeuvre into a firing position without giving their own position away by creating excessive noise, or exhausting their own batteries.
Nevertheless, Launders made the necessary calculations, made assumptions about U-864's defensive manoeuvres, and ordered the firing of all four of his bowtorpedo tubes. The torpedoes were fired with a 17.5 second delay between each pair, and at variable depths. The computation thus differs fundamentally from those performed by analogue torpedo fire-control computers which regarded the target in strictly 2D terms with a constant depth determined by the target's draught. 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 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.

< THUS INSPIRED & ONCE ONLY, I PERFORMED A SIMILAR ACTION IN ONE OF THE SH'S 'HISTORIC MISSIONS' WHERE MY UBOAT WAS AGAINST THREE ENEMY SUBS AND THE LAST WAS SUBMERGED AT WHAT I PRESUMED WAS PERISCOPE DEPTH 13 METERS: MY TARGET'S DRAUGHT CROSSING MY 'T' FROM STARBOARD TO PORT AT A PRESUMED 7 KNOTS(UNDERWATER FLANK SPEED?); I FIRED BLIND: ALL FOUR TUBES WITH STEAM EELS- SET ON FAST- WITH A 2 DEGREE PORT SPREAD DIFFERENTIATION AT UNDER A 1000 METERS RANGE AND SWITCHED TO TORPEDO CAM IN TIME TO SEE ONE HIT ALLES KAPUT! MIT A MODICUM OF CUNNING 10% AND 'DUMB LUCK' 90% IMHO PS: THE SINKING OF U-864 STILL HAUNTS US TODAY

The fragmented wreck contains 67 tonnes of toxic liquid mercury. Over time part of the toxic metal had spread over an area of 30,000 square metres.

A supportive stone filling was made in 2016 to secure the seabed area to prevent the front part of the wreck from sliding down. The seabed was covered with a layer of sand (0.5 metres thick) and then further covered with 160,000 tonnes of rock.

WHAT A HORRIBLE MESS! & DON'T EAT THE FISH! https://en.wikipedia.org/wiki/German_submarine_U-864

[TheCod]

Originally Posted by Aktungbby

WHAT A HORRIBLE MESS! & DON'T EAT THE FISH! https://en.wikipedia.org/wiki/German_submarine_U-864

Great story. I didn't know. Thank you!

[TheCod]

Originally Posted by PanicEnsues

The Germans had approximately the same tech as Allies in that regard: If they knew the position, heading, and speed of a target, they COULD fire from any depth.

However, given that:

A) they couldn't use their targeting data computers (which used input from the periscope or mounted binoculars for bearing input),
B) if they ship changed course they may not know about it early enough to recalculate, and
C) torpedoes were the most precious, limited commodity to a sub,

neither side seemed willing to risk a miss by firing blind.


For Crash Dive, I tried to apply the same logic. Since you can see the exact position, speed and heading of any ship that's close enough, you can take a shot from any depth, but you can't use the TDC (you have to manually line up the bearing/time lines).

Hope that helps!

-Scott

Thanks Scott!