Rn vs IJN

[Shortround6]

All of those powers were sufficiently powerful at that time to participate in the looting of China. My point in naming all the others is just to highlight that Japan had few competitors in 1941

Actually the Japanese were making around 3 times the Iron and Steel per year that the Italians made, Italy may have been in the "big 5" but it was a real light weight, Which puts everybody else in perspective.

What naval aircraft was superior to the A6M prior to the arrival of the Hellcat? We can go back to that other thread and discuss in more and more detail, but I don't think the A6M is inferior to the land based fighters either until you start getting to Merlin 60 / DB 605 / BMW 801 powered fighters, and even then only within their usually limited range. And even that is debatable (we can discuss it in the other thread).

Well, the F4F??
But we are getting into tactics and training and resupply (of pilots for one thing).

We know in the actual real world, Spitfires and Hurricanes were slaughtered by A6Ms. I know there were a lot of factors contributing to the Spitfire losses in Darwin, but most of those same factors were also in play with P-39 units, P-40 units, P-38 units, F2A units, etc. etc.

And again, we are getting into tactics and training.

I think you can say very long range and 'hyper-maneuverability', along with heavy armament.

Sorry, using the armament of 1940 fighter for most of 1942 does not make you advanced.

For the D3A, it seemed to be an extremely accurate dive bomber.

See early posts, Training/experience vs quality of the aircraft, we may never know. But if it was the plane then replacement air crew should have done well with it. Not as good but done OK.

I think the Zero was more than sufficient for a couple of years. A6M5 is a pretty challenging opponent, as we can see even F4Us were not exactly dominating them.

The A6M5 don't begin to show up in Service until Sept/Oct 1943.
Lets not forget that the A6M3 (with two speed supercharger ) didn't show up until Aug 1942. And that was Hamp with the short wing and reduced range so a lot of the Early Guadalcanal fighting was done with older A6M2. They eventually got long wing A6M3s but that was in Jan 1943? (planes came off the production line in Dec 1942)

 

[Thumpalumpacus]

<edited, misfired reply>

 

[Wild_Bill_Kelso]

Actually the Japanese were making around 3 times the Iron and Steel per year that the Italians made, Italy may have been in the "big 5" but it was a real light weight, Which puts everybody else in perspective.

After a while, under fascism, loyalty becomes the only criteria for advancement. It tends to gum up the works.

Well, the F4F??
But we are getting into tactics and training and resupply (of pilots for one thing).

With improved / special tactics, the F4F achieved near parity. But I don't think we can say it was superior either in terms of capabilities (like range) or in direct combat between one type and the other. Especially when we look at the real loss numbers on both sides. Of course we can't always tell what part of a given outcome is due to training, leadership, tactics, environmental conditions, mission parameters etc., but as you pointed out upthread or in another thread, with aircraft we can usually compare relatively large data sets which tend to even out the other factors. With F4F vs A6M we can, I think do that.

And again, we are getting into tactics and training.

My point is that units flying all these types were up against similar (very daunting) challenges. Some were able to make their aircraft work, more or less. Almost all of the P-38 units, most of the P-40 units. Others not as much - most of the P-39 units, most of the F2A units.

Sorry, using the armament of 1940 fighter for most of 1942 does not make you advanced.

I said heavily armed, not 'advanced'. So lets compare to aircraft actually in combat in 1942. I put red asterix next to those with more firepower, double if a lot more.

A6M2 - 2 x 20mm (60 rounds), 2 x LMG
A6M3 - 2 x 20mm (100 rounds), 2 x LMG

Italy
MC 200 - 2 x 12.7mm (slow firing)
G.50 - 2 x 12.7mm (slow firing)
CR 42 - 2 x 12.7mm (slow firing)
MC 202 - 2x 12.7mm (slow firing), 2 x LMG
Re 2000 - 2 x 12.7mm (slow firing), 2 x LMG

Germany
Bf 109F-2 - 1 x 15mm, 2 x LMG
Bf 109F-4 - 1 x 20mm, 2 x LMG
Bf 110 - 2 x 20mm, 4 x LMG **

Britain
Spitfire Mk VB - 2 x 20mm (60 rounds), 4 x LMG *
Spitfire Mk VC - 2 x 20mm (120 rounds), 4 x LMG *
Fulmar - 8 x LMG
Hurricane IIB - 12 x LMG *
Hurricane IIC - 4 x 20mm (60 rounds) **
Beaufighter - 4 x 20mm, 6 x LMG **
Whirlwind - 4 x 20mm **

Soviet
I-16 - 2 x 20mm (60 rounds?) 2 x LMG (fast firing) [Also used by Chinese]
LaGG-3 (early) - 1 x 20mm (120 rounds), 1 x 12.7mm
Yak-1 - 1 x 20mm, 1 x 12.7mm
Yak-7 - 1 x 20mm, 2 x LMG (fast firing)

US
F4F-3 - 4 x 12.7mm [Also used by British]
F4F-4 - 6 x 12.7mm *
F2A - 4 x 12.7mm [Also used by British]
P-36 - 4 x LMG or 2 x 12.7mm [Also used by British eventually]
P-43 - 4 x 12.7mm [Also used by Chinese]
P-40 B/C - 2 x 12.7mm (slow), 4 x LMG
P-40 E/K - 6 x 12.7mm [Also used by British and Chinese] *
P-40 F/L - 4 or 6 x 12.7mm *
P-400 - 1 x 20mm, 2 x 12.7mm (slow), 4 x LMG *
P-39 - 1 x 37mm, 2 x 12.7mm (slow) *
P-38 - 1 x 20mm, 4 x 12.7mm *
P-51A - 4 x 12.7mm or 6 x 12.7mm [Also used by British]

So the British and American fighters were generally more heavily armed, though it's worth noting that the two most heavily armed Ango-American fighters - P-39 and Hurricane II, both did poorly against the A6M. All the guns really don't matter unless you can line them up.

See early posts, Training/experience vs quality of the aircraft, we may never know. But if it was the plane then replacement air crew should have done well with it. Not as good but done OK.

Of course we know that the Japanese were not well positioned for attrition war

The A6M5 don't begin to show up in Service until Sept/Oct 1943.
Lets not forget that the A6M3 (with two speed supercharger ) didn't show up until Aug 1942. And that was Hamp with the short wing and reduced range so a lot of the Early Guadalcanal fighting was done with older A6M2. They eventually got long wing A6M3s but that was in Jan 1943? (planes came off the production line in Dec 1942)

They did take a long time to uprgrade the A6M, but the A6M2 was still pretty lethal through 1942.

 

[Thumpalumpacus]

I don't believe either Shokaku or Zuikaku were deathtraps. They were well on par with the Yorktowns. They got pounded and came back for more.
I was watching some Unauthorized History Of The Pacific War videos. Its commentators are a retired USN Admiral and a retired USN Captain, a former sub skipper. Their guest was Jonathan Parshall. They were discussing the strengths and weaknesses of the two nations carriers. I haven't seen it in a while so some latitude, please. I believe Mr. Parshall said that the Shokaku and Zuikaku carried fewer aircraft than the Yorktowns was due to operational doctrine. I think he mentioned something about deck parks and where aircraft were fueled up, bombed up and warmed up. I don't remember the specifics.

Small niggle: Seth Paridan, Captain Toti's co-host, was not in military. He was, and is, the Asst Director of the Mississippi Armed Forces Museum.

And you're absolutely right, the 'Kakus were tough ships. Shokaku took three 1000-lb bombs at Coral Sea and still sailed home for repairs. She was also at Santa Cruz, where she took between 3 and 6 bombs of various sizes -- again sailing home for repairs. Going by Wiki, apologies:

[...] Vertical protection consisted of 215 mm (8.5 in) on the main armor deck over the machinery, magazines and aviation fuel tanks, while horizontal protection consisted of 215 mm (8.5 in) along the waterline belt abreast the machinery spaces, reducing to 150 mm (5.9 in) outboard of the magazines.[4]

As Parshall and Tully demonstrate in Shattered Sword, Kido Butai's destruction was largely the result of Japanese arming and fueling doctrine as opposed to flimsy builds. Once they modified this doctrine, you don't see fireballs arising from airstrikes again. Shokaku and Taiho were both blown up by leaking avgas getting ignited.

UHotPW is a great channel. Readers will find it here: https://www.youtube.com/@UnauthorizedHistoryPacificWar/featured

 

[Shortround6]

All true, and I think I've been pretty fair about the (relatively good) British torpedoes in this discussion. Not just via Wellingtons either. Subs too, ships too. Sure it is an asset for the British.

I know it is difficult but we all need to identify which torpedoes we are talking about at times.
Japanese Aerial torpedoes were high speed 41-43 kts but rather short ranged, usually 2000 meters. Warheads kept getting heavier, there was a little juggling of ranges with the later ones with heavier warheads, but that is 1500 meters with a huge warhead, I am not sure what was supposed to carry it as it was about 450lbs heavier than the earlier torpedoes.
Early British 18on torpedo was was 40kts at 1500yds range. the Mid war and later torpedo was good for 40kts and 2500yds with a heavier war head. I am not going to worry about 1-3 kts of speed. Most torpedo bombers tried to drop at less than max range to reduce chances of the ship evading. The extra range of the Japanese torpedo is an advantage. If was critical???

I've heard this claim made many times. I don't really buy it. There was clearly a problem with just about all of the Allied troops in the early part of the war - British, French, American, Russian. Some of this had to do with leadership at all levels, some had to do with kit, with supply and logistics, with communication, with tactics and strategies.

The BEF actually did fairly well in France, Belgium in 1940. Only 1 division was judged as being well trained on arrival. The others were trained by hard work over a cold winter. The British Artillery was bit lacking, not quite up to numbers for the field artillery with some divisions even making do with 18pdrs and/or 4.5in howitzers (max range 6800yds) and the British Corp and Army artillery was bad joke. Some of the guns were older than a lot of the gunners manning them.
"Not to worry lads, The RAF Battles and Blenheims and Lysanders will soon sort out any Jerry's too far away for our artillery" we know how that worked out.
Not to mention the 4 Bren guns per battalion as the establishment AA. Next level was the 3in AA guns at division level.

The BEF in Belgium had to conduct a fighting withdrawal while in constant contact with the enemy (generally considered one of the most difficult maneuvers/operations) with the allies on each side sometimes conducting their own withdrawal without telling the British.
It did not turn into a rout and the British conducted the withdrawal with a minimum of incidents (won't say there were none).

 

[Wild_Bill_Kelso]

I know it is difficult but we all need to identify which torpedoes we are talking about at times.
Japanese Aerial torpedoes were high speed 41-43 kts but rather short ranged, usually 2000 meters. Warheads kept getting heavier, there was a little juggling of ranges with the later ones with heavier warheads, but that is 1500 meters with a huge warhead, I am not sure what was supposed to carry it as it was about 450lbs heavier than the earlier torpedoes.
Early British 18on torpedo was was 40kts at 1500yds range. the Mid war and later torpedo was good for 40kts and 2500yds with a heavier war head. I am not going to worry about 1-3 kts of speed. Most torpedo bombers tried to drop at less than max range to reduce chances of the ship evading. The extra range of the Japanese torpedo is an advantage. If was critical???

The major factors for air launched torpedoes were really the height and speed of the drop, and if they worked. Torpedoes that had to be dropped lower and slower, as most of the early war weapons did, were much more dangerous for the aircraft crews and much less likely to hit anything unless the enemy was asleep at the wheel (see Taranto) or had trouble aiming at them (Bismarck).

Speed and range (in the water) are nice but don't matter as much.

The BEF actually did fairly well in France, Belgium in 1940. Only 1 division was judged as being well trained on arrival. The others were trained by hard work over a cold winter. The British Artillery was bit lacking, not quite up to numbers for the field artillery with some divisions even making do with 18pdrs and/or 4.5in howitzers (max range 6800yds) and the British Corp and Army artillery was bad joke. Some of the guns were older than a lot of the gunners manning them.
"Not to worry lads, The RAF Battles and Blenheims and Lysanders will soon sort out any Jerry's too far away for our artillery" we know how that worked out.
Not to mention the 4 Bren guns per battalion as the establishment AA. Next level was the 3in AA guns at division level.

By my reading, they were fairly well trounced in action with the Germans. They did get out, and the Dunkirk evacuation was a triumph. Partly this was due to the Germans getting nervous and deciding to stop. Partly it was due to the British themselves holding their unit cohesion. Partly due to French allies fighting rear-guard actions, IIRC.

Regardless, I think we are seeing the same thing - they learned that many aspects of their kit from the Fairey Battles to the light AAA resources were inadequate. Tanks too, Matildas notwithstanding. They got a bit lucky and got out. That gave them a chance to fix a lot of this stuff. And also to relieve a lot of (high, middle and low ranking) officers and NCOs who couldn't cut it.

The BEF in Belgium had to conduct a fighting withdrawal while in constant contact with the enemy (generally considered one of the most difficult maneuvers/operations) with the allies on each side sometimes conducting their own withdrawal without telling the British.
It did not turn into a rout and the British conducted the withdrawal with a minimum of incidents (won't say there were none).

My understanding was that the French units fought pretty hard in covering the Dunkirk evacuation though it's been a while since I've read anything about it.

 

[Shortround6]

most of the F2A units.

Maybe I am just too detail orientated but the F2A units were something of a disaster.
You also had several different F2A's.
The US one, yes, count it, ONE. F2A unit. A Marine squadron that the F2As when the Navy gave them away.
We know a lot the troubles the British Buffalo units had, questionable engines, questionable fuel tank protection, problems with the guns, no early warning or not much. Little or no AA protecting the airfields. And the fact that most of the pilots were not combat veterans.
Dutch squadrons?

After a while, under fascism, loyalty becomes the only criteria for advancement. It tends to gum up the works.

Not sure what this refers to.
Italian industry was actually very small and raw materials were somewhere on the far side of scarce. Italy actually imported a fair amount of British coal during the 30s. Germany had to promise to supply coal by train to get Italy to join in. If you don't have iron ore and you don't have coal you don't make steel, no matter what ideology you have. It also takes a lot of time to build steel works.

 

[Wild_Bill_Kelso]

Maybe I am just too detail orientated but the F2A units were something of a disaster.
You also had several different F2A's.
The US one, yes, count it, ONE. F2A unit. A Marine squadron that the F2As when the Navy gave them away.
We know a lot the troubles the British Buffalo units had, questionable engines, questionable fuel tank protection, problems with the guns, no early warning or not much. Little or no AA protecting the airfields. And the fact that most of the pilots were not combat veterans.
Dutch squadrons?

A few of the British Buffalo units did ok, and made a bunch of 'fixes' which helped a lot (like stripping weight). You had some guys like Geoff Fiskin who made Ace. The Japanese, according to their doctrine, just didn't give them the time or space to rally.

Not sure what this refers to.
Italian industry was actually very small and raw materials were somewhere on the far side of scarce. Italy actually imported a fair amount of British coal during the 30s. Germany had to promise to supply coal by train to get Italy to join in. If you don't have iron ore and you don't have coal you don't make steel, no matter what ideology you have. It also takes a lot of time to build steel works.

I think Italy could have overcome limitations to coal and other resources. My understanding (from having read a few detailed papers on this) was that general economic efficiency actually went way down under fascism. Partly that was due to politics interfering with trade. Partly due to just sheer corruption. It's a myth that Mussolini got the trains running on time, let's just say that. If you want trains that run on time go to Switzerland.

 

[Glider]

All this is interesting. But the thing is, every nation had their blind spots, their errors, the cultural flaws, their shocking omissions in preparation for the inevitable war. You are focusing a lot on radar, which England was ahead on and Japan behind (but, not so behind that they didn't figure it out). But it is just as shocking and incomprehensible that the Royal Navy having a two person, 270 mph fighter, and a biplane strike aircraft for their carriers. Or the US having a torpedo that didn't work for the first 3 years of the war. Or why the early British tanks were so bad. Etc.

The Japanese had the best carrier fighter in the world in 1941, and it still was until the Hellcat showed up in mid 1943. - Agreed
The Japanese had the world's best naval torpedoes basically until the end of the war. By a wide margin. - Agreed
The Japanese had the best naval optics in the world, which ended up being copied by both the US and the UK - Agreed, but the worst Radar which pretty much cancelled it out
The Japanese navy leadership and sailors were some of the best trained in the world for night combat - Questionable as the RN were well trained in night fighting and had Radar
The Japanese had some of the best trained aviators in the world, - Agreed
The Japanese had either the best, or the second best naval strike aircraft in the world 1941 in the D3A - Agreed
The Japanese had one of the most disciplined, aggressive land armies in the world in 1941. - Questionable disciplined, aggressive, but with dreadful tactics, terrible tanks and poor artillery
The Japanese had the largest and most powerful battleships in the world by the end of 1941. - I would call it a draw. Yamato clearly the best, Nagato class matched by Nelson, Kongo's matched by modernised British BC's, Fuso's and Ise matched by QE class and the British had the R class left over. R class was worse than the rest but capable of giving a good account of themselves. Then we have the KGV class
The Japanese had the best float plane fighter in the world in 1941-43 in the A6M2-N. After that they got the even better N1K1. - Agreed but I am not aware of these floatplanes having a significant impact in combat
The Japanese had the best flying boat in the world in the H8K - Agreed but the Sunderland was a good second best
The Japanese had the best, or second best aircraft carriers in the world in 1941 - Agreed

Cruisers Draw - Japanese Heavy Cruisers were very good, but the light cruisers were very poor.
Destroyers Draw - Japanese destroyers clearly had the best torpedo's but the RN had more destroyers, were much better equipped with Radar and well trained
Submarines - RN Advantage as Japanese designs were very mixed and tactics very poor. Japanese submarines achieved very little
Escorts - Clear RN advantages in numbers, designs, equipment and training.

 

[Wild_Bill_Kelso]

Cruisers Draw - Japanese Heavy Cruisers were very good, but the light cruisers were very poor.
Destroyers Draw - Japanese destroyers clearly had the best torpedo's but the RN had more destroyers, were much better equipped with Radar and well trained
Submarines - RN Advantage as Japanese designs were very mixed and tactics very poor. Japanese submarines achieved very little
Escorts - Clear RN advantages in numbers, designs, equipment and training.

That seems fair, I could argue on Destroyers due to the type 92 but I'll buy it.

How do you make use of the Escorts in the Pacific. I was thinking ASW and rescue maybe, but they are slow right? Do they have good range?

 

[Thumpalumpacus]

How do you make use of the Escorts in the Pacific. I was thinking ASW and rescue maybe, but they are slow right? Do they have good range?

This is an important point. The RN DDs spent a lot of time training against sub threats. IJN, not nearly so much. IJN ASW doctrine and practice was generally lousy. Their ASW equipment left a lot to be desired, too.

 

[Shortround6]

Soviet
I-16 - 2 x 20mm (60 rounds?) 2 x LMG (fast firing) [Also used by Chinese]
Ok, most had 4 X LMG and those had about eight times the fire power of the two LMG in the cowl of of the Zero.
The ones that had 2 X 20mm had 180rpg and the guns fired a lot faster (800rpm) than the guns in Zero
LaGG-3 (early) - 1 x 20mm (120 rounds), 1 x 12.7mm
no, the early Laggs had assorted guns, a lot used the single 20mm with 120 rounds and two 7.62s (fast firing)with 325rpg.
Yak-1 - 1 x 20mm, 1 x 12.7mm
Yaks were all over the place with guns, starting with the 20mm and two 7.62s and then going to the 12.7mm
Yak-7B - 1 x 20mm, 2 x 7.62mm (fast firing)
Yak-7B - 1 x 20mm 140rpg, 2 x 12.7mm (fast firing) 225rpg

The 12.7mm gun has a nominal cycle rate of 1000rpm with 800-900rpm when firing through the propeller. each round is more powerful than the US .50cal.

 

[Glider]

That seems fair, I could argue on Destroyers due to the type 92 but I'll buy it.

How do you make use of the Escorts in the Pacific. I was thinking ASW and rescue maybe, but they are slow right? Do they have good range?

The Pacific is a battle of Logistics. The RN had some excellent escort vessels some of which were heavily armed for AA and A/S warfare cumulating in the Egret class with 8 x 4in aa guns and Bittern / Black Swan classes with 6 x 4in AA guns and a heavy A/S war load of 40 Depth Charges (increased to 110). In addition there were corvettes which were no good against aircraft but very effective against submarines.
There can be little doubt that the RN was in a much better position to defend its supply lines than the Japanese Navy and that can be crucial. The difference in numbers was huge with Japan starting the war with four (yes 4) ocean going escorts and the merchant fleet basically defenceless.

 

[Wild_Bill_Kelso]

Soviet
I-16 - 2 x 20mm (60 rounds?) 2 x LMG (fast firing) [Also used by Chinese]
Ok, most had 4 X LMG and those had about eight times the fire power of the two LMG in the cowl of of the Zero.
The ones that had 2 X 20mm had 180rpg and the guns fired a lot faster (800rpm) than the guns in Zero
LaGG-3 (early) - 1 x 20mm (120 rounds), 1 x 12.7mm
no, the early Laggs had assorted guns, a lot used the single 20mm with 120 rounds and two 7.62s (fast firing)with 325rpg.
Yak-1 - 1 x 20mm, 1 x 12.7mm
Yaks were all over the place with guns, starting with the 20mm and two 7.62s and then going to the 12.7mm
Yak-7B - 1 x 20mm, 2 x 7.62mm (fast firing)
Yak-7B - 1 x 20mm 140rpg, 2 x 12.7mm (fast firing) 225rpg

The 12.7mm gun has a nominal cycle rate of 1000rpm with 800-900rpm when firing through the propeller. each round is more powerful than the US .50cal.

The Soviet fighter planes all had a mix of guns. The I-16s with the twin 20mm were used in China from 1938 if I'm remembering right and were also used in the later stages of the Spanish Civil War. I think by the time of Barbarossa most of the I-16s in fighter units in Russia had the twin 20mm types (IIRC Type 18 and 24 and some later ones)

The LaGG-3, Yak-1, Yak 7, including B versions of both, and Yak 9 all alternated between one 12.7mm or one or two 7.62mm machine guns, or one of each. It varied by the individual factory they came from and the unit they flew with. I was trying to be generous by assigining the 12.7mm which was the heavier mix until some started getting twin 12.7mm plus the ShVak

Regardless - I think 2 x 20mm plus two light machine guns is still heavier armament than one 20mm + one machine gun, though the ammution capacity is a limitation on the A6M2, and the hub mounted cannon are more accurate.

The first real change to this pattern was when they started coming in with the Shvestov Engined La 5 / 7 etc. series which had two 20mm and in some of the last versions, three 20mm.

 

[Wild_Bill_Kelso]

The Pacific is a battle of Logistics. The RN had some excellent escort vessels some of which were heavily armed for AA and A/S warfare cumulating in the Egret class with 8 x 4in aa guns and Bittern / Black Swan classes with 6 x 4in AA guns and a heavy A/S war load of 40 Depth Charges (increased to 110). In addition there were corvettes which were no good against aircraft but very effective against submarines.
There can be little doubt that the RN was in a much better position to defend its supply lines than the Japanese Navy and that can be crucial. The difference in numbers was huge with Japan starting the war with four (yes 4) ocean going escorts and the merchant fleet basically defenceless.

Well, I wouldn't say defenseless since they did have a rather impressive fleet of warships defending the home islands, but I see your point.

I wonder if the IJN would have developed their ASW capabilities more quickly if the American torpedoes had been working properly?

 

[Wild_Bill_Kelso]

This is an important point. The RN DDs spent a lot of time training against sub threats. IJN, not nearly so much. IJN ASW doctrine and practice was generally lousy. Their ASW equipment left a lot to be desired, too.

They are referring specifically to these corvette or 'sloop' sized escort ships which were used to defend the Atlantic convoys. About 2/3 the size of a Fletcher class Destroyer.

Like these puppies Black Swan-class sloop - Wikipedia

 

[Glider]

I wonder if the IJN would have developed their ASW capabilities more quickly if the American torpedoes had been working properly?

I don't know but there is no doubt that they would have lost a lot more merchant ships, a lot faster and that would have helped concentrate the minds.

That said the problem at the start wasn't just the American torpedo's, the captains of the US subs were very cautions and timid. It took a change in leadership and a ruthless weeding out of the risk averse captains before the US Submarines started to make a difference.

 

[Wild_Bill_Kelso]

I don't know but there is no doubt that they would have lost a lot more merchant ships, a lot faster and that would have helped concentrate the minds.

That said the problem at the start wasn't just the American torpedo's, the captains of the US subs were very cautions and timid. It took a change in leadership and a ruthless weeding out of the risk averse captains before the US Submarines started to make a difference.

I think I'd be timid too if I knew my torpedoes didn't work (and occasionally did really unpleasant things like circling back and hitting my sub and then deciding to work...)

 

[SaparotRob]

In the peacetime U.S. Navy, sub skippers had trained not to be detected. During the fleet exercises if a sub's periscope was spotted, the sub was going to be "sunk". I'm ignorant of the mechanics of judging success or failure in those exercises. My takeaway is U.S. sub skippers were trained and rewarded to not take risks. It doesn't help one's career if one loses one's boat. That was in peacetime.

 

[Thumpalumpacus]

They are referring specifically to these corvette or 'sloop' sized escort ships which were used to defend the Atlantic convoys. About 2/3 the size of a Fletcher class Destroyer.

Like these puppies Black Swan-class sloop - Wikipedia

Useful ASW platforms. Tight turn-radius, good sonar, would need an air umbrella approaching Singapore, and superior to Japanese light ASW in both equipment and training. Able to handle ATL waters, too.