A pair of historical questions..

[Aviv]

I have a pair of historical questions I thought of in the last week, so I thought you old sea-dogs could give me some information and feed my curiosity.

First, in my reading I read that a lot of submarines (especially uboats) were sunk by aircrafts. Why didn't they just dive straight when they detected the airplane on radar? For example in the game, I can detect and dive to 30 meters before he can even close to me and is over the horizon. Why did air attack cause such a problem to submarine crews? How frequent were the air patrols?

Second, I was reading the other day (bored recently) about how crews can escape from submarines. I learnt that those two small hatches at the back of the submarine (with one at almost 45 degrees) is part of the system which allows sailors to escape; the "escape trunk" (more information on Wikipedia). I wanted to know how successfull was that to allow people to escape and survive sunked submarines?

I guess that's all!
Thanks!

[gmuno]

To the first question:
The uboats didn't have a a radar for spotting planes. They had some rudimentary RWRs, but that's it.
The only subs which came with radar were the US one's.
For the Why not diving: They dove allright. Diving takes time and even if the plane('s) arrived after the sub had vanished from the surface, it's wake and the diving position were still visible from above.

to the second question:
The escape-hatches only worked in shallow waters and even there not so well. The exact numbers of survivors... no idea.

[CCIP]

I have a pair of historical questions I thought of in the last week, so I thought you old sea-dogs could give me some information and feed my curiosity.

First, in my reading I read that a lot of submarines (especially uboats) were sunk by aircrafts. Why didn't they just dive straight when they detected the airplane on radar? For example in the game, I can detect and dive to 30 meters before he can even close to me and is over the horizon. Why did air attack cause such a problem to submarine crews? How frequent were the air patrols?

The crucial difference is that the game's radar is very reliable and leaves you with no doubt - either it's contact, or no contact. Real radar was not this reliable, and could give confusing signals, or let small aircraft slip past. Likewise, diving took time - depending on the submarine's alert state and position, it could be unprepared to dive as quickly as we usually do in game.

Very few US boats were lost to aircraft in any case. Most were lost to destroyers. In fact, almost as many were lost to friendly aircraft as to enemy aircraft.

As far as U-boats, it's a very different story. They did not have effective air search radar like the US boats, while the aircraft they faced had sophisticated radar and other effective ASW equipment themselves. A vast number of U-boat sinkings were by long-range radar-equipped aircraft at night, when the boats had practically no warning.


Second, I was reading the other day (bored recently) about how crews can escape from submarines. I learnt that those two small hatches at the back of the submarine (with one at almost 45 degrees) is part of the system which allows sailors to escape; the "escape trunk" (more information on Wikipedia). I wanted to know how successfull was that to allow people to escape and survive sunked submarines?

Not very! All of these systems were designed for escaping subs at depths of no more than 100 ft, and because most subs operated and were sunk at greater depths, this system was not very useful. In practice, some crews escaped from even deeper wrecks (to about 200ft), although this was difficult. Interestingly, the Russians had the most sophisticated escape gear of the time, which allowed them to escape from subs down to 300ft. It still was based on the same principle, and ultimately not terribly effective.

Escape also relied on compartments remaining watertight and able to retain some air to allow the crew to escape - so if the hull had major ruptures, which are often what sunk the sub in the first place, it offered little help. The sub also had to be relatively upright on the bottom - not a guarantee in a sinking. The escape process itself required some time to prepare by partially flooding the compartment being escaped from. Here things like smoke or chlorine gas from batteries, or hypothermia could also kill the crew before they could complete this process. Even after they left the sub, the crew could die of suffocation, hypothermia and decompression sickness on the way up. Escaping from a sub sinking in deeper waters was 100% impossible. Unless it could blow ballast and surface, a sinking submarine = a dead crew. It would be impossible to open escape hatches against pressure, unless the pressure was equalized. Equalizing pressure = flooding most of the compartment. Flooding most of the compartment on a sinking sub = dropping like a rock and being crushed. In other words, submarine crews were doomed once their sub lost its reserve buoyancy in open sea.

However as far as I know, all major submarine-operating countries in WWII had cases of crews escaping from shallow wrecks using these systems. Most of these escapes were partial (i.e. not all of the crew survived, and in many cases, only a few did). The most famous of these in US service would've been the USS Tang, sunk by a circling torpedo. Only 9 of her crew survived (including the captain).

[Dread Knot]

How frequent were the air patrols?



In the Bay of Biscay, quite frequent. One advantage the Allies had in the Atlantic was that U-Boats operating out of French ports had to cross this relatively small geographical area which the Allies could easily cover with aircraft as the war wore on. During Operations Enclose and Derange in 1943 the Allies put hundreds of planes over the bay at one time making life miserable for the U-Boats, which without radar had to hope to spot them in time by eye or radar detector. American submarines in the Pacific, by contrast had vast swathes of open ocean uncovered by planes from which to close in on Japan and it's maritime lifelines. Radar was a pricless asset which gave ample warning on those rare occasions when Japanese planes were a threat. Japan, unlike the Allies didn't put actual radar equipped ASW planes (like the Q1W Lorna) into the air until the war was almost over.

[Hinrich Schwab]

Why did air attack cause such a problem to submarine crews?

The answer is fairly rudimentary. Aircraft could attack a submarine at any time without fear of effective* retaliation. While anti-aircraft guns could and did shoot down aircraft, the threat of bombs, torpedoes or depth charges often compelled subs to dive, suppressing the submarine. Since the snorkel did not become available until near the end of the war for the Germans, (The U.S. copied snorkels after the war ended, but had no equivalent) aircraft directly interfered with the battery recharge and air exchange cycle needed for old diesel-electric subs. Even if a plane could not take out a sub or a u-boat, it could force a dive and limit its range.

The greatest difference between theaters is the evolution of air-based ASW. While I won't repeat what has already been said about radar, tactics evolved in the Atlantic that eventually led to the end of U-Boat effectiveness. Britain saw that 1-on-1 with a lone U-Boat was risky because of the flak gun and pilots began tag-teaming U-Boats. One plane annoyed the flak gunner while the other performed a bombing run. Unless the U-Boat was one of the uncommon models with multiple flak guns (excluding the specialized flak boats, which failed miserably), the flak gunner obviously could not shoot at both at once. If he turned to shoot the other plane, the former decoy would make the attack run. Another tactical evolution involved steep divebombing out of the sun. By the time the plane could be heard, let alone seen, it was too late. Later in the war, pilots would annoy U-Boats outside the maximum range of the flak gun and wait for reinforcements to show up to gang up on and sink the sub. The U-Boat's greatest strengths, torpedoes and underwater stealth, were useless against aircraft. All a U-Boat could do was hide, if it was able.

Another reason for this overwhelming superiority was Britain's prioritization of ASW strategy and tactics. Conversely, in Imperial Japan, the American submarine threat wan't taken seriously until the damage was already done and, in effect, too late. Imperial Japanese naval strategy prioritized surface ship combat, in accordance with doctrine established by Alfred Thayer Mahan. Likewise, this same adherence to doctrine is what made it difficult for the IJN to accept airplanes and carrier combat despite its success. In regards to ASW, Japan just didn't care until it saw the American sub fleet decimate its merchant marine. On occasion, planes would locate or annoy an American sub, but there was never any strategic or tactical doctrine regarding engaging American subs.

As the relative distances involved in both theaters was already discussed, I won't repeat that factor, either.

In short, aircraft could operate against submarines with relative impunity, with the right amount of tactics and equipment. England realized this relatively early in the war due to necessity and resource focus while Japan really did not care until it was too late to levy any real resistance.


*The term "effective" is used because of the advantages of the airplane, attacking from its medium over a submarine operating within its respective medium.

[Ducimus]

Second, I was reading the other day (bored recently) about how crews can escape from submarines. I learnt that those two small hatches at the back of the submarine (with one at almost 45 degrees) is part of the system which allows sailors to escape; the "escape trunk" (more information on Wikipedia). I wanted to know how successfull was that to allow people to escape and survive sunked submarines?


One of the most famous accounts of escaping a stricken submarine was the USS Tang.

A first hand account of sorts can be read here:
http://ss563.org/306/survivors.html

[Randomizer]

I think that it is wrong to state that the IJN did not "care" about the US submarine threat. Rather there were very real cultural and doctrinal bars to the navy acting on the submarine threat in a manner similar to the way the allies treated the U-Boat war. They did realize that there was a threat and so formed convoys from the onset but there was little in the way of systemic convoy defence and management as there was in the Atlantic.

There was no civilian oversight for the Japanese armed forces and so any logistic or resource concerns by government were met by parochial responses. In Western practice, the cabinet imposes strategic policies on the military who then are obligated to carry them out. Such decisions might include allocation of resources for ASW, convoying, shipbuilding etc. Since the Navy Minister in cabinet was a serving admiral, his policies would reflect those that were in the interest of the Navy rather than the country. We see this in the way that the IJN treated the submarine threat, it was not that they did not care, it's that using destroyers to escort warships and planes to strike aggressively against Allied combat forces was more suited to the Naval ethos than escorting merchant ships.

Also, by nature ASW is passive, the British Royal Navy had an extraordinarily difficult time in WW1 wrapping its head around the fact that the nature of submarine warfare required patience above all else. In a service that prided itself on the maxim "Our Front Line is the Enemy Shore", waiting passively for a U-Boat to attack a convoy so it could be counter-attacked seemed to be all wrong. It took near defeat in 1917 to ram home the realization that in ASW, the Targets must come to you. The Japanese Navy never made that leap of faith until far too late.

In the IJN the submarine force was tasked with the destruction of warships and for scouting in accordance with the requirements of the battlefleet as its first priority. As mentioned above, they were inculcated into Mahan's theories Sea Power that were never applicable to their situation. The IJN leadership never realized this and continually expended forces in order to facilitate the Final Decisive Battle until they had no more resources to spend.

So, far from not caring, the Japanese Navy just had other priorities that better matched its cultural and doctrinal worldview and without civilian oversight to prioritize their tasks in the national interest, they failed to act according to the threat of the US submarine service. When the true situation finally came home to roost, it was too late to act effectively.

[Ducimus]

You'll find interesting information from the Japanese themselves here:
http://www.ibiblio.org/hyperwar/AAF/USSBS/IJO/index.html

[Hinrich Schwab]

I think that it is wrong to state that the IJN did not "care" about the US submarine threat. Rather there were very real cultural and doctrinal bars to the navy acting on the submarine threat in a manner similar to the way the allies treated the U-Boat war. They did realize that there was a threat and so formed convoys from the onset but there was little in the way of systemic convoy defence and management as there was in the Atlantic.



Perhaps I was being a bit blunt when I said that. Regarding doctrinal bars, this is a bit easier to analyze. The conflict of three different forms of naval warfare in play, Mahan-Battleship Theory, the new Carrier-based aerial navy and ASW made it prohibitive for Japan to pursue all three at once. Japan had followed the Mahan-Battleship doctrine and invested a great deal of resources into perfecting it, especially after it saw success against Russia during the Russo-Japanese War prior to WWI. The military always errs to established conventions. Air power and Carrier-based strategy was just proving itself during the outset of World War II. However, the failure at Midway made it difficult for Japan to recover to pursue carrier tactics the way the United States did, defaulting it back to Battleship strategy. With so much time and energy refining one methdology and testing another, ASW was simply left on the back burner.

Culturally, Imperial Japan was still honor-bound in much of the same way as its feudal predecessor. ASW detail was frowned upon because one was passively waiting and guarding merchants, rather than fighting the enemy in direct combat. It was a job no one really wanted to do because there was less prestige in it. the IJN failed to anticipate American guerre de course (militarized piracy) because of the initial lack of submarines at the outset and viewed guerre de course with equal disdain to ASW detail because of the obvious association with piracy. I won't conjecture as to how disdainful the IJN felt personally, only that the disdain was sufficient to create the weakness. I probably would have been better off to say that, "...they did not care for...[ASW]".

[Randomizer]

You'll find interesting information from the Japanese themselves here:
http://www.ibiblio.org/hyperwar/AAF/USSBS/IJO/index.html
Had not perused the naval chapters of the Pacific USSBS before, thanks. Relevant entries include Nav #'s 11, 37, 45, 56 and 57.

Couple of things to note, the presence of senior officers (a RAdm) as convoy escort Group Commander since most Allied escort group commanders (as opposed to Hunter-Killer Group Commanders) were generally far more junior. As the war progressed they probably had more admirals than they could effectively employ. By nature these officers would tend to be doctrinally set in their ways and less able to cope with command problems that likely were outside their previous service experience.

Also the conversion of at least one naval ASW squadron to a Special Attack (Kamikaze) role in the summer of 1944, something that reinforces my observation re placing service interests over national interests.

Edit
@ Schwartzritter.

The problem was that Mahan's theories of sea power ceased to be relevant any time after 1905 and can be said to have been to all intents and purposes dead after the Falkland's battle, 8 December 1914 and almost 30-years to the day before Pearl Harbor. He dragged several generations of willing naval officers and more than a few partisan politicians down the wrong strategic path. Those officers that realized that Mahan had feet of clay frequently went into submarines and naval aviation during the inter-war period and they were the largely ones who rose to senior command in the crucible of naval warfare from 1939-45. Except in Japan, where even the revered Yamamoto remained an unreconstructed Mahaniac until the day he died and his replacements were doctrinally even more conservative.

[Ducimus]

INTERROGATION NAV NO. 11
JAPANESE NAVAL ESCORT OF SHIPPING AND SHIPPING LOSSES
Interrogation of: Captain OI, Atsushi, IJN, a permanent officer of the Japanese Navy who has had staff college training. He served as a Staff Officer of the Combined Escort Fleet from its organization in November 1943 until the war's end.
http://www.ibiblio.org/hyperwar/AAF/USSBS/IJO/IJO-11.html



INTERROGATION NAV NO. 37
ATTACKS ON JAPANESE SHIPPING
Interrogation of: Lt. Comdr. YATSUI, Noriteru, IJN; a naval officer of 8 years service. He was Navigation Officer of the cruiser Oi when she was sunk in July 1944 and served on the staff of the 7th Escort Convoy from that time until the end of the war.
http://www.ibiblio.org/hyperwar/AAF/USSBS/IJO/IJO-37.html


INTERROGATION NAV NO. 45
ESCORT AND PROTECTION OF SHIPPING
Interrogation of: Lieut. Comdr. YASUMOTO, Shisei, IJN; Commander of the escort vessel Shiokaze, March 1944 to June 1945; Staff Officer of 103rd Convoy Escort Squadron, Seventh Fleet, from June 1945 to end of war.
http://www.ibiblio.org/hyperwar/AAF/USSBS/IJO/IJO-45.html


INTERROGATION NAV NO. 47
CONVOY ESCORT AND PROTECTION OF SHIPPING
Interrogation of: Rear Admiral HORIUCHI, Shigetada, IJN, Chief of Staff, First Escort Fleet from May 1944 to December 1944; Commanding 901 Air Group, FORMOSA from January 1945 to September 1945.
http://www.ibiblio.org/hyperwar/AAF/USSBS/IJO/IJO-47.html


INTERROGATION NAV NO. 53
ESCORT AND PROTECTION OF SHIPPING
Interrogation of: Commander KUWAHARA, Tadao, IJNR (retired), who was commander of an escort vessel engaged in convoy work between MOJI and SINGAPORE; civilian experience as master of N.Y.K. liners; while in Military Affairs Office, assisted in recruiting and training crews for Naval supply ships and civilian ships.
http://www.ibiblio.org/hyperwar/AAF/USSBS/IJO/IJO-53.html


INTERROGATION NAV NO. 63
ANTI-SUBMARINE TRAINING AND EQUIPMENT
Interrogation of: Lieutenant Commander OKAMOTO, T.; Staff Officer of First Escort Fleet Air Squadron and (general Headquarters, Grand Escort Fleet.
http://www.ibiblio.org/hyperwar/AAF/USSBS/IJO/IJO-63.html

[CptChacal]

I learnt that those two small hatches at the back of the submarine (with one at almost 45 degrees) is part of the system which allows sailors to escape; the "escape trunk" (more information on Wikipedia).

The 45-degree hatch is the torpedo loading hatch and has no escape trunk.

[Lannes]

You'll find interesting information from the Japanese themselves here:
http://www.ibiblio.org/hyperwar/AAF/USSBS/IJO/index.html

Very nice source material, Ducimus....

Thanks! :salute:

[Armistead]

I think the only crew to ever use the escape hatch was the famous Tang. O'Kane was on the bridge when he fired his last torpedo which was a circle runner that came back and hit Tang. Some of the crew that survived made it to the bow torp room and several escaped using the escape hatch in a few hundred feet of water

I think the book about it is called "Escape from the Deep"...great story. Tells mostly of the last patrol and the men using the escape hatch, several used it but died before making it. Also tells of the wounded and others too afraid to try it that accepted their death with quiet courage.

Also gets into detail of those that escaped being captured and their time as POW's being tortured, etc..

[Jan Kyster]

You'll find interesting information from the Japanese themselves here:
http://www.ibiblio.org/hyperwar/AAF/USSBS/IJO/index.htmlMaybe some interesting stuff here as well, War Diary (CVs):

http://wwiiarchives.net/servlet/documents/usa/125/0


And the complete collection of Submarine War Patrol Reports:

http://wwiiarchives.net/servlet/documents/usa/100/0

[Aviv]

Very interesting, guys. This should give me some interesting reading to do. I already read about the USS Tang, it's a good experiance to read, especially with the prison parts afterward. I had heard how the Japanese Navy did not focus on protecting merchants (the same reason how they did not use their submarines to attack merchants).

@CptChacal I always thought it was the torpedo loading hatch too, but then how do you explain there's not one for the front tubes and also, this picture looks the same like the part of the submarine http://www.navy.mil/view_single.asp?id=8910

[Ducimus]

And the complete collection of Submarine War Patrol Reports:

http://wwiiarchives.net/servlet/documents/usa/100/0

That is much easier to navigate then the collection i knew of.

[Sailor Steve]

@CptChacal I always thought it was the torpedo loading hatch too, but then how do you explain there's not one for the front tubes and also, this picture looks the same like the part of the submarine http://www.navy.mil/view_single.asp?id=8910
It looks to me like the vertical hatch behind the sailor is the escape hatch and he's actually posing in the torpedo loading hatch. These drawings show the layout of a Gato class sub, with everything marked.
http://www.navsource.org/archives/08/0821203.jpg
http://www.navsource.org/archives/08/0821230.jpg

[Aviv]

I see, I see. In that case my bad, apologies. I like the blueprints though!

[Sailor Steve]

No bads, no apologies necessary. You might still be right. My observation is no better than yours. :sunny:

[mobucks]

There was an access hatch that the deck gun crew would use for access to the gun and magazine.

[Nisgeis]

If you want an account of a peace time US rescue, have a read of 'The Terrible Hours' by Peter Maas. It describes the sinking of the USS Squalus in 1939 (after the main induction valve didn't close properley during a dive) and the subsequent rescue attempts. It gives a good idea of all the problems involved in a rescue close to home, with ships available to help and the use of the distress buoys (which in war time were welded in place).

If you are on your own in the war zone, the procedure for escape also varies on the type of sub you are in and where you are on that sub. If you are in the rear torpedo room of a US sub, you have to unbolt the inner part of the escape hatch (the skirt), lower it down, turn it over and then bolt it back on again, to form a long tube which will hold air pressure in the escape hatch. You then flood the whole room at once and the tube allows an air gap to form, which you can use to breath whilst you fit your escape gear. Now try doing the same when you decide to wait for the destroyer that has just sunk you to leave the area, with a broken arm, no light except hand held lamps, the temperature rising due to escaping high pressure air (and possibly battery fire also) and with chlorine gas from the water that got into the battery making you choke or possibly rising carbon dioxide.

The forward torpedo room has an escape trunk, which you get a few men in, flood, open the door, get out, close the door, drain down (assuming you have high pressure air left) and repeat. It sounds quite quick, but in practice it took a very long time to complete. Each time you drain the trunk, the air pressure in the torpedo room rises making it hotter and more uncomfortable for the remaining survivors.

Once you have escaped, you have to ascend at the correct rate, so you can breathe out and in an equalise the air pressure in your lungs with the surrounding dropping sea pressure - ascend too fast, or hold your breath and you die. Then you find yourself on the surface with at the time limitted survival gear 300 miles from shore.

The escape is a pretty tricky thing to do with everything working perfectly and who knows what sort of damage things have taken - maybe the hatches no longer seal or won't open.

The USS Pampanito site has the following link regarding the escape procedue: http://www.maritime.org/tech/escape.htm and also on the Pampanito site there are some photos of the escape trunk with a handy virtual panoramic photo you can rotate and zoom in on.

HMS Thetis sank in 1939 in Liverpool bay and only four people escaped. The submarine had no damage (the sinking was caused by both ends of a forward torpedo tube being open at the same time) and she was in 140 feet of water. I think the stern was even sticking out of the water.

As for U-Boats being sunk, I am fairly sure I read that most attacks were pretty ineffectual, with depth charges being dropped on U-Boats caught on the surface doing little damage and the difficulty of hitting a target if it had already submerged. I think most sinkings of U-Boats came about when the homing air dropped torpedo was introduced, which was pretty much a one shot kill when dropped into the swirl caused by a recently submerged U-Boat. But that may not be the case as I don't have any stats to hand on the U-Boat sinkings.

[mobucks]

HK groups were pretty effective at killing a U-boat, one destroyer would stop and listen while the others made depth charge runs.