Why do American subs have a less test depth in comparison to a German UBoat?

[A Soviet Fanboi]

So I was doing my usual patrols in SH4 FOTRS, then I suddenly got attacked by a G4M1 Betty Bomber(I forgot to turn on my SD radar). I recieved a hull damage of 83 and I crash dived immediately after shooting down the bomber. I was in a depth of 113ft and suddenly my Chief Engineer spammed with words like Compressor Damaged! Pumps Damaged! We have heavy floading! Etc,etc. I was surprised and checked on my damage and yes it was really serious but it was too late and I got crushed due to water pressure. But the thing is I was at a depth of 113ft only and still I got crushed, 113ft is like 35ft and that's quiet less. I am damn sure that if I was on a type IXC u-boat on SH3 (Because I haven't played the u-boat campaign in SH4 yet) I would have survived. So the question is, why did American subs had a very weak hull or a very less test depth in comparison to a uboat?

[propbeanie]

83 of 100 leaves you 17% of your hull protection, which tain't much... The US subs were rated lower than the German, but only from an engineering perspective. The U-Boats were tested for crush, and rather conservatively also, but the US boats were not, and the depth was decided by an equation someone had on a piece of paper, so if the paper said the boat could go to 600 feet (roughly 200 meters), then they said you could safely dive to 300 feet (100 meters) and be "safe". Ultra-conservative on diving depth. Crush depth might have been even deeper, and quite a few US boats did go below 600 feet - going by guess-timates, since their depth gauges didn't register deeper than 600. But if you take that 600 foot figure, and multiply it by 17%, you come up with 102 feet... death at 102 feet instead of 600+. Use 1000 feet instead, and that is 170 feet deep for death... That is one aspect of submarine warfare the submariners did not have though - a "gauge" on how much hull structure integrity they have left. :salute:

[Bubblehead1980]

So I was doing my usual patrols in SH4 FOTRS, then I suddenly got attacked by a G4M1 Betty Bomber(I forgot to turn on my SD radar). I recieved a hull damage of 83 and I crash dived immediately after shooting down the bomber. I was in a depth of 113ft and suddenly my Chief Engineer spammed with words like Compressor Damaged! Pumps Damaged! We have heavy floading! Etc,etc. I was surprised and checked on my damage and yes it was really serious but it was too late and I got crushed due to water pressure. But the thing is I was at a depth of 113ft only and still I got crushed, 113ft is like 35ft and that's quiet less. I am damn sure that if I was on a type IXC u-boat on SH3 (Because I haven't played the u-boat campaign in SH4 yet) I would have survived. So the question is, why did American subs had a very weak hull or a very less test depth in comparison to a uboat?

Yea as beanie said, your hull integrity was severely compromised, 83 percent means 83 percent damaged, should not have tried to dive and turned for home immediately. Your boat was close to a total constructive loss.Not sure if FOTRS kept the number same but used to be if hull had 90 percent damage and you made it back to port, they retired the boat and her skipper typically.


Just a follow up, US subs could dive much much deeper than advertised, especially the Balao and Tench Class subs. Gato's went much deeper than their 300 ft test depth during war and even older boats such as Porpoise class went quite deep when forced to under combat conditions. I recall the Pollack went to 550 at one point, 250 ft test depth and a riveted hull I believe. They were sturdy, well built boats that could dive quite deep but for safety reasons, were rated quite conservatively in regards to max diving depth.

Most of time they were not required to go quite so deep and some submarine commanders were not willing to push their boats that deep unless forced by flooding etc, others such as O Kane did, taking the Tang to 600 feet during sea trials and in combat due to flooding went to 612 feet I believe it was.

[Red Devil]

In Das Boot they went down to 700 meters - allegedly. I'm not so sure the Med was that deep off Gibraltar where they say they were

[KaleunMarco]

In Das Boot they went down to 700 meters - allegedly. I'm not so sure the Med was that deep off Gibraltar where they say they were

700 m is 2296.588 feet.
no WWII sub from any nation could survive a dive to 2296 feet.
that's Hollywood.

[Mad Mardigan]

In Das Boot they went down to 700 meters - allegedly. I'm not so sure the Med was that deep off Gibraltar where they say they were

If I recall rightly.. the gauge only went to 300, in the movie.. will have to see of watching it again, to cross check that.

Even if the gauge in the movie was slated as saying 600 (or even 700) meters.. as KM correctly pointed out... that's By Golly Bollywood for ya... anything for the dramatic nail biting suspense of movies, such as Das Boot or other action movies. :yep: up to including even the horror genre...ALL to be taken with a grain heavy dose of salt. :arrgh!: :up:

M. M.

:Kaleun_Salute:

[KaleunMarco]

If I recall rightly.. the gauge only went to 300, in the movie.. will have to see of watching it again, to cross check that.

Even if the gauge in the movie was slated as saying 600 (or even 700) meters.. as KM correctly pointed out... that's By Golly Bollywood for ya... anything for the dramatic nail biting suspense of movies, such as Das Boot or other action movies. :yep: up to including even the horror genre...ALL to be taken with a grain heavy dose of salt. :arrgh!: :up:

M. M.

:Kaleun_Salute:

i recall the last time i watch Das Boot and the Kaleun gave the order: Deeper and the diving officer announced 400 or 500 m, i had to laugh. i believe they reached 700 m when they were "resting" on the bottom trying to fix the diesels. I believe that the German Kaleun in The Enemy Below also takes his Type 7 to 700 m.

that is another bugaboo with me...not only with DB with the other (mostly American) submarine movies...this resting on the bottom.
can't do that.
a sub has too many pumps located on the lower portion of the hull, pumping in either direction, to rest anywhere but in the water. But it's great entertainment isn't it?

[Bubblehead1980]

i recall the last time i watch Das Boot and the Kaleun gave the order: Deeper and the diving officer announced 400 or 500 m, i had to laugh. i believe they reached 700 m when they were "resting" on the bottom trying to fix the diesels. I believe that the German Kaleun in The Enemy Below also takes his Type 7 to 700 m.

that is another bugaboo with me...not only with DB with the other (mostly American) submarine movies...this resting on the bottom.
can't do that.
a sub has too many pumps located on the lower portion of the hull, pumping in either direction, to rest anywhere but in the water. But it's great entertainment isn't it?


Numerous US subs did lay to on the bottom when damaged trying to make repairs. Tambor in Feb 1944 in South China Sea comes to mind, 17 hours was on bottom being depth charged USS Seahorse in 1945 off Tsushima Straits, was under 15 hours or so as well, on the bottom. S boat in Aleutians was sinking to crush depth hit a shelf, one in the philippines. Multiple other instances

[KaleunMarco]

Numerous US subs did lay to on the bottom when damaged trying to make repairs. Tambor in Feb 1944 in South China Sea comes to mind, 17 hours was on bottom being depth charged USS Seahorse in 1945 off Tsushima Straits, was under 15 hours or so as well, on the bottom. S boat in Aleutians was sinking to crush depth hit a shelf, one in the philippines. Multiple other instances

very dangerous.
you go first.
45 second mark
https://www.youtube.com/watch?v=ClwIj3x24Q4

[propbeanie]

From the "reliable" Wikipedia for a Type VII:
Test depth: 230 m (750 ft) -Calculated crush depth: 250–295 m (820–968 ft)
Very similar to the Gato figures, but the American boat designers were more nervous about their advertised "test" depth. Notice that the German crush depth is also calculated, and is very similar to the US calculations. Only the US used 1/2 of what they knew was a "safe" depth as the test depth. Think about it though, you are in a boat that is "safe" to 700 feet, and someone is raining depth charges and maybe a hedge hog or squid volley or two at you at that depth, and I do believe that everyone of us would have to change our shorts after just the first nearby explosion... Most submarine officers were highly educated men, most of them engineers in one field or another, and all could guess what the designers knew...

[KaleunMarco]

From the "reliable" Wikipedia for a Type VII:
Test depth: 230 m (750 ft) -Calculated crush depth: 250–295 m (820–968 ft)

230 meters is significantly less than the Hollywood depth of 700 meters.

[A Soviet Fanboi]

In Das Boot they went down to 700 meters - allegedly. I'm not so sure the Med was that deep off Gibraltar where they say they were
Holy Cow even modern subs don't go that deep, I think you were mistaken.:k_confused:

[A Soviet Fanboi]

From the "reliable" Wikipedia for a Type VII:
Test depth: 230 m (750 ft) -Calculated crush depth: 250–295 m (820–968 ft)
Very similar to the Gato figures, but the American boat designers were more nervous about their advertised "test" depth. Notice that the German crush depth is also calculated, and is very similar to the US calculations. Only the US used 1/2 of what they knew was a "safe" depth as the test depth. Think about it though, you are in a boat that is "safe" to 700 feet, and someone is raining depth charges and maybe a hedge hog or squid volley or two at you at that depth, and I do believe that everyone of us would have to change our shorts after just the first nearby explosion... Most submarine officers were highly educated men, most of them engineers in one field or another, and all could guess what the designers knew...
Test depth of Type VII C was 150m. Beyond the 150m is known as critical depth.

[ETR3(SS)]

that is another bugaboo with me...not only with DB with the other (mostly American) submarine movies...this resting on the bottom.
can't do that.
a sub has too many pumps located on the lower portion of the hull, pumping in either direction, to rest anywhere but in the water. But it's great entertainment isn't it?

Numerous US subs did lay to on the bottom when damaged trying to make repairs. Tambor in Feb 1944 in South China Sea comes to mind, 17 hours was on bottom being depth charged USS Seahorse in 1945 off Tsushima Straits, was under 15 hours or so as well, on the bottom. S boat in Aleutians was sinking to crush depth hit a shelf, one in the philippines. Multiple other instancesAs Bubblehead has stated (and I'll expand on) diesel boats most certainly can rest on the sea bottom. Most nuc boats cannot, or could not, rest on the bottom due to Main Seawater and Auxiliary Seawater suction and discharge. The exceptions I believe were SSN-575 Seawolf, SSGN-587 Halibut, and SSN-683 Parche. With no reactor plant to keep running, there's no need for a MSW/ASW system or to take a suction from or discharge to the sea while submerged in a diesel boat.

[propbeanie]

Just be sure and retract your heads... lol - pick-up your feet!

[les green01]

in the Das Boot book i got they got everything in feet instead of meters in the movie they use meters so i'm thinking they didnt convert the feet to meters in the 700ft part also in the movie one part they doing a sound check at 30 meters he orders scope dept then starts using the oservation scope

[A Soviet Fanboi]

As Bubblehead has stated (and I'll expand on) diesel boats most certainly can rest on the sea bottom. Most nuc boats cannot, or could not, rest on the bottom due to Main Seawater and Auxiliary Seawater suction and discharge. The exceptions I believe were SSN-575 Seawolf, SSGN-587 Halibut, and SSN-683 Parche. With no reactor plant to keep running, there's no need for a MSW/ASW system or to take a suction from or discharge to the sea while submerged in a diesel boat.
What's the difference between Main Sea water suction and discharge, and Natural Circulation of sea water in Nuclear submarines?

[mikesn9]

What's the difference between Main Sea water suction and discharge, and Natural Circulation of sea water in Nuclear submarines?


Seawater is the start of the cooling "system" it cools things that cool things, etc till the reactor is cooled. It takes Pumps to move the water fast enough.

If the boat uses natural circulation the cool the reactor: boy are they in trouble.

they have lost most of the functions of the engineering spaces.
Time to bend over and kiss your arse goodbye.


Former reactor operator here. If you didn't sink, Naval Reactors would have your arse anyway.

[A Soviet Fanboi]

Seawater is the start of the cooling "system" it cools things that cool things, etc till the reactor is cooled. It takes Pumps to move the water fast enough.

If the boat uses natural circulation the cool the reactor: boy are they in trouble.

they have lost most of the functions of the engineering spaces.
Time to bend over and kiss your arse goodbye.


Former reactor operator here. If you didn't sink, Naval Reactors would have your arse anyway.
Lmao, I read in Wikipedia that the recent Yasen class SSGN of Russia uses Natural Circulation of water in order to cool it's reactors. It also stated that this made the submarine much more quieter.

[Red Devil]

700 m is 2296.588 feet.
no WWII sub from any nation could survive a dive to 2296 feet.
that's Hollywood.

you are probably right, maybe it was FEET, big difference. Itys been a while since I watch it. Danke much

[ETR3(SS)]

What's the difference between Main Sea water suction and discharge, and Natural Circulation of sea water in Nuclear submarines?Main Seawater is the cooling source for the steam side of the plant. It runs through the condensers (located under the Main Engines and Turbine Generators) cooling the steam and turning it back into liquid water. So MSW Suction is the inlet to the system drawing seawater in, whereas MSW discharge is the outlet.

Seawater is the start of the cooling "system" it cools things that cool things, etc till the reactor is cooled. It takes Pumps to move the water fast enough.

If the boat uses natural circulation the cool the reactor: boy are they in trouble.

they have lost most of the functions of the engineering spaces.
Time to bend over and kiss your arse goodbye.


Former reactor operator here. If you didn't sink, Naval Reactors would have your arse anyway.The S8G was designed with natural circulation in mind, that was installed on the Ohio's. There were a couple proof of concept builds before that though, I believe the Narwhal had a nat circ plant with MSW scoops (S5G). I'm not a nuc, but I understand more than the average coner.:03: