WI Japanese VII Uboats

What if the Japanese goverment in 1930s build 20+ VII Uboats under license from Germany and have a German military mission train the crews(let's say the Japanese navy see the potential of German Uboats)?how much effect woul Japanese navy having 20+ VII Uboats have on the early years of the pacific war ww2?
 
What if the Japanese goverment in 1930s build 20+ VII Uboats under license from Germany and have a German military mission train the crews(let's say the Japanese navy see the potential of German Uboats)?how much effect woul Japanese navy having 20+ VII Uboats have on the early years of the pacific war ww2?
Why would the Japanese need to do this? The Japanese already had excellent submarines, well trained crews, and most important, torpedoes that worked.
 
Why were the allies not afraid of Japanese submarine and afraid of German submarines
The Japanese submarine doctrine was based on the faulty premise, namely that submarines' main task was to attack the American battle fleet and weaken it as it was steaming towards Japan before it would meet the IJN in the decisive battle. Besides the fact that they had made a wrong prediction regarding the eventual American naval strategy, they had also started to realize problems with this on a tactical level already in the late-1930's during naval exercises (where they essentially found out that it didn't work at all how they had thought it would) but hadn't really come up with anything to fix problems with it before the war started.
 

CalBear

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What if the Japanese goverment in 1930s build 20+ VII Uboats under license from Germany and have a German military mission train the crews(let's say the Japanese navy see the potential of German Uboats)?how much effect woul Japanese navy having 20+ VII Uboats have on the early years of the pacific war ww2?
IJN's boats and especially torpedoes were better than the Type VII. The Jpanese differed from the KM in the overall naval strategy they followed (which was pretty much the only way to go since the Reich had no overall naval strategy). Type B1 was six knots faster on the surface, half knot faster submerged and had close to double the range (16,000 miles vs. 8,500 for Type VII). It also carried the excellent Type 95 torpedo with had more range, was much faster (up to 7 knots depending on range setting) and with a warhead that was 33% large than the standard German weapon. The B-1 class also carried three additional reloads.

Better question is what difference would have made if the KM had 20 B1 class boats.
 
A Japanese sub from the 1920s had better stats than the early Type IXs.
Japan doesn't need anything from Germany in terms of naval stuff.

The only problem i noticed with IJN subs is their low maximum depth.
Type B1 only had test depth of 100m for example.
 
What if the Japanese goverment in 1930s build 20+ VII Uboats under license from Germany and have a German military mission train the crews(let's say the Japanese navy see the potential of German Uboats)?how much effect woul Japanese navy having 20+ VII Uboats have on the early years of the pacific war ww2?
The USN would kill them. The Japanese would not use them properly. The Type VII dived deeper and was somewhat quieter, but if you do not know what you are doing, the characteristics that give a really marginal advantage *(such as superior sonar) means nothing in the overall scheme of things.

IJN's boats and especially torpedoes were better than the Type VII. The Jpanese differed from the KM in the overall naval strategy they followed (which was pretty much the only way to go since the Reich had no overall naval strategy). Type B1 was six knots faster on the surface, half knot faster submerged and had close to double the range (16,000 miles vs. 8,500 for Type VII). It also carried the excellent Type 95 torpedo with had more range, was much faster (up to 7 knots depending on range setting) and with a warhead that was 33% large than the standard German weapon. The B-1 class also carried three additional reloads.

Better question is what difference would have made if the KM had 20 B1 class boats.
Probably easier kills for the RN, because the IJN boats were shallow divers, (100 meters was test depth 125 meters was crush), terrible underwater in maneuverability and noisy even by German U-boat noisy standards. They become especially vulnerable in the dive evolution, because they are very slow divers and turners (2 minutes and 7 boat lengths).

The Type 95 torpedoes were "good" out to 3,000 meters and then comes the nose wander problem caused by gyro tumble. Occasional 5,000 meter shots and hits were known and recorded, but that was the exception and not the general rule for the fish. Visibility for Japanese tracking parties through their periscopes was good even by German standards, but nobody human is going to see well at night (German attack preference time) through a periscope beyond 3,200 meters (~2 miles) in the North Atlantic day or night because of weather effects. Night surface attack in an I-15 is contra-indicated by IJN WWII tactics, so if the IJN sends instructors to teach proper stalk and underwater ambush technique, IJN style, the Germans are not going to pay any attention to their allies because they have their "own ideas" and who are these Japanese anyway?

IOW, each navy built their boats and weapon effectors to what they thought they needed and organized their tactical procedures around the mission. I-boats were there to sink Ameican battleships in attrit and decrease, and Type VIIs were there to sink British freighters in an idiotic tonnage blockade attrition strategy. Both types of subs DIED in droves, because the navies who ordered them built were functionally clueless as to how to actually employ submarines.

What made the British and Americans better, were what they tried for in their subs was; underwater dash speed, tight turn out, huge bow salvoes of fish, quieting and the best "sea worthiness" qualities surfaced or dived they could obtain in their boats. I argue that the GATOs were marginal as fleet boats as the I-15 counterpart, but they were good enough as general purpose platforms in their overall characteristics (90 meter test; 175+ meter crush, proved in battle. Those boats were massively overbuilt.) to fill fleet and commerce destroyer roles. Overall they were QUIET on the battery and hard to bracket in a turning fight against enemy escorts. Not the fastest divers (70 seconds to 70 meters) but they turned tight for their length (about 4 lengths)and UNLIKE German or Japanese boats, they did not fall out of controlled trim in radical underwater maneuvers.

Give the Germans a GATO or the Japanese for that matter, and one needs to worry. Those guys might figure out how to actually use a submarine.
 
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CalBear

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The USN would kill them. The Japanese would not use them properly. The Type VII dived deeper and was somewhat quieter, but if you do not know what you are doing, the characteristics that give a really marginal advantage *(such as superior sonar) means nothing in the overall scheme of things.



Probably easier kills for the RN, because the IJN boats were shallow divers, (100 meters was test depth 125 meters was crush), terrible underwater in maneuverability and noisy even by German U-boat noisy standards. They become especially vulnerable in the dive evolution, because they are very slow divers and turners (2 minutes and 7 boat lengths).

The Type 95 torpedoes were "good" out to 3,000 meters and then comes the nose wander problem caused by gyro tumble. Occasional 5,000 meter shots and hits were known and recorded, but that was the exception and not the general rule for the fish. Visibility for Japanese tracking parties through their periscopes was good even by German standards, but nobody human is going to see well at night (German attack preference time) through a periscope beyond 3,200 meters (~2 miles) in the North Atlantic day or night because of weather effects. Night surface attack in an I-15 is contra-indicated by IJN WWII tactics, so if the IJN sends instructors to teach proper stalk and underwater ambush technique, IJN style, the Germans are not going to pay any attention to their allies because they have their "own ideas" and who are these Japanese anyway?

IOW, each navy built their boats and weapon effectors to what they thought they needed and organized their tactical procedures around the mission. I-boats were there to sink Ameican battleships in attrit and decrease, and Type VIIs were there to sink British freighters in an idiotic tonnage blockade attrition strategy. Both types of subs DIED in droves, because the navies who ordered them built were functionally clueless as to how to actually employ submarines.

What made the British and Americans better, were what they tried for in their subs was; underwater dash speed, tight turn out, huge bow salvoes of fish, quieting and the best "sea worthiness" qualities surfaced or dived they could obtain in their boats. I argue that the GATOs were marginal as fleet boats as the I-15 counterpart, but they were good enough as general purpose platforms in their overall characteristics (90 meter test; 175+ meter crush, proved in battle. Those boats were massively overbuilt.) to fill fleet and commerce destroyer roles. Overall they were QUIET on the battery and hard to bracket in a turning fight against enemy escorts. Not the fastest divers (70 seconds to 70 meters) but they turned tight for their length (about 4 lengths)and UNLIKE German or Japanese boats, they did not fall out of controlled trim in radical underwater maneuvers.

Give the Germans a GATO or the Japanese for that matter, and one needs to worry. Those guys might figure out how to actually use a submarine.
Last sentence is the key, especially for the Japanese. Even where they were totally on the defensive and lacked the capital ships need to even attempt the "decisive battle" strategy they never turned their boats loose on the vast American supply lines that snaked across a quarter of the planet.
 
The USN would kill them. The Japanese would not use them properly. The Type VII dived deeper and was somewhat quieter, but if you do not know what you are doing, the characteristics that give a really marginal advantage *(such as superior sonar) means nothing in the overall scheme of things.



Probably easier kills for the RN, because the IJN boats were shallow divers, (100 meters was test depth 125 meters was crush), terrible underwater in maneuverability and noisy even by German U-boat noisy standards. They become especially vulnerable in the dive evolution, because they are very slow divers and turners (2 minutes and 7 boat lengths).

The Type 95 torpedoes were "good" out to 3,000 meters and then comes the nose wander problem caused by gyro tumble. Occasional 5,000 meter shots and hits were known and recorded, but that was the exception and not the general rule for the fish. Visibility for Japanese tracking parties through their periscopes was good even by German standards, but nobody human is going to see well at night (German attack preference time) through a periscope beyond 3,200 meters (~2 miles) in the North Atlantic day or night because of weather effects. Night surface attack in an I-15 is contra-indicated by IJN WWII tactics, so if the IJN sends instructors to teach proper stalk and underwater ambush technique, IJN style, the Germans are not going to pay any attention to their allies because they have their "own ideas" and who are these Japanese anyway?

IOW, each navy built their boats and weapon effectors to what they thought they needed and organized their tactical procedures around the mission. I-boats were there to sink Ameican battleships in attrit and decrease, and Type VIIs were there to sink British freighters in an idiotic tonnage blockade attrition strategy. Both types of subs DIED in droves, because the navies who ordered them built were functionally clueless as to how to actually employ submarines.

What made the British and Americans better, were what they tried for in their subs was; underwater dash speed, tight turn out, huge bow salvoes of fish, quieting and the best "sea worthiness" qualities surfaced or dived they could obtain in their boats. I argue that the GATOs were marginal as fleet boats as the I-15 counterpart, but they were good enough as general purpose platforms in their overall characteristics (90 meter test; 175+ meter crush, proved in battle. Those boats were massively overbuilt.) to fill fleet and commerce destroyer roles. Overall they were QUIET on the battery and hard to bracket in a turning fight against enemy escorts. Not the fastest divers (70 seconds to 70 meters) but they turned tight for their length (about 4 lengths)and UNLIKE German or Japanese boats, they did not fall out of controlled trim in radical underwater maneuvers.

Give the Germans a GATO or the Japanese for that matter, and one needs to worry. Those guys might figure out how to actually use a submarine.
When you say GATO you mean Gato class submarines?
 
AFAIK the Soviet S-class (Stalinets) subs were pretty good for their size.
Good maneuverability, same torpedo tube arrangement as the Type IX, quite fast with good underwater range, better range than the Type VII.
The only significant drawback of the S-class is it's low test depth, which can be attributed to the use of rivets in the pressure hull. A fully welded version of the S-class would have a better test depth.
And it was designed by NV Ingenieurskantoor voor Scheepsbouw, a shell company that was part of the German rearmament effort.
The blueprints for the S-class were given to the USSR in late 1933.

IMO the Germans should have just taken the blueprint of the S-class, modified it slightly and made it into the ITTL Type VII instead of the OTL Type VII. A better sub with a shorter design time because the blueprints were ready in late 1933. Modifications would take about 1 year at most and construction can begin.
The Japanese could have also used the S-class design, I think they would have benefited from it.
 
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DougM

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A few reasons exist for why the UBoat was feared more then a IJN sub,
First off the Atlantic had a LOT more merchant shipping going on. As well as troop transports and such so the pickings were richer.
The Atlantic is smaller so easier to find targets.
GB being an island needs supplies from outside. TheMajor Alied positions in pacific. Not so much. You are not staving the US or Australia even if you sink 100% of the merchant ships.
The US did not have as strong a navel fleet in the Atlantic (in general)
The US and GB viewed the Atlantic as a defensive war (stop germany from sinking merchants) but the Pacific was an offensive war.

So it was not the submarines that mad the s difference in the reputation but the way the two campaigns were fought
 
The problem with turning Japanese submarines loose against the sea lanes was one of capacity. Japan operated a total of 174 submarines in the whole war. The Germans built over 700 Type VIIs alone.

I would argue they had the right idea in using their submarines as high value asset killers and in 1942 they were effective in that role keeping Saratoga out of three of four carrier battles, sinking Wasp in the weeks before Santa Cruz, and making sure Y-Town did not get back to PH after Midway.

The problem was that US capacity eventually made itself felt and they pushed them away performing ancillary missions like supplying isolated garrisons, flying reconnaissance planes over South African and US west coast cities (seriously why?), and attacking British shipping in the Indian Ocean.
 
So if you were put in charge (and also as insane as they were) of the Japanese Navy in 1930s you'd recommend they simply copy the American submarine plans?
Look at the US WWI era P or S Class. U-Boat had far higher crew for similar weapon set, though a bit longer ranged and far better dive depth.
note VIIC was slower submerged. S class had better undersea streamlining, also reflected in U-Boat needing 3X the diesel power to go 2 knots faster on the surface

Class and type: Type VIIC submarine

Displacement: 769 tonnes (757 long tons) surfaced 871 t (857 long tons) submerged
Length: 67.10 m (220 ft 2 in) o/a
Beam: 6.20 m (20 ft 4 in) o/a
Propulsion:
  • 2 shafts
  • 2 × diesel engines 2,800–3,200 PS (2,100–2,400 kW; 2,800–3,200 bhp)
  • 2 × electric motors 750 PS (550 kW; 740 shp)
Speed: 17.7 knots (32.8 km/h; 20.4 mph) submerged speed of 7.6 knots (14.1 km/h; 8.7 mph)
Range:8,500 nmi (15,700 km; 9,800 mi) at 10 knots (19 km/h; 12 mph) surfaced
Test depth:230 m (750 ft)
Complement: 4 officers, 40–56 enlisted
Armament:
  • 4 × 53.3 cm (21 in) torpedo (bow) tubes
  • one stern tube
  • 14 × torpedoes or 26 TMA mines
  • 1 × 8.8 cm (3.46 in) deck gun (220 rounds)
  • 1 × 2 cm (0.79 in) C/30 anti-aircraft gun
VS

S Class, late

Displacement: 903 tons surfaced, 1230 Submerged
Length: 240 ft (73 m)
Beam: 22 ft (6.7 m)
Propulsion:2 shafts
  • 2 shafts
  • 2 × Busch-Sulzer diesels, 900 hp (670 kW)
  • 2 × Ridgway electric motors, 750 horsepower (560 kW)
Speed: 15 knots (28 km/h; 17 mph) surface, 11 knots (20 km/h) submerged
Range: 8,000 nautical miles (15,000 km) at 10 kn (19 km/h; 12 mph) surfaced
Test depth: 200 ft (61 m)
Complement: 38
Armament:
  • 4 × 21 inch (533 mm) torpedo tubes (bow), 12 torpedoes
  • 1 x 21 inch stern tube with 2 additional torpedoes)
  • 1 × 4-inch (102 mm)/50 caliber deck gun
  • 4 x Browning Machine guns

Now going with Modern USN Subs, it's even better.

The VII really were not that great, other than better test depth. Welding takes care of that.
 
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Why were the allies not afraid of Japanese submarine and afraid of German submarines
Because the Japanese used their submarines as auxiliaries to the fleet, not as commerce raiders. It was the way they were used not the quality of the boats or crews that made the Uboats such a threat.
 
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