IJN Soryu's and USS Wasp's Durability and Usefulness

[Kantai Kessen]

As we naval history nerds know, the Japanese aircraft carrier Soryu and the American aircraft carrier Wasp died horrible deaths during the Pacific War. However, what stands out is that both were caught with their pants down: Soryu getting jumped by Yorktown's dive bombers while refuelling and rearming her own dive bombers at Midway, not helped by the fact that IJN damage control was not great, and Wasp getting torpedoed by I-19 while conducting flight ops and having her gas lines filled with fuel - she died hard and her crew were very brave, but she still succumbed.

I have been considering scenarios in which both carriers don't die their respective deaths and get to fight in more carrier battles. So, assuming that neither ship is in so compromising a position - they know an attack is coming, have drained their fuel lines and are conducting evasive manoeuvres, protected by screen ships - how much damage can they take, while staying afloat and in a repairable state? It probably is not much, given how fragile these two carriers were, but I would be grateful for information and an analysis from anyone.

I'll divide this into categories:
(a) Just bomb damage
(b) Just torpedo damage
(c) A mixture of (a) and (b)
(d) Shell damage (for fun - why not?)

For further consideration:
(A) Each ship has their OTL 1942 crew on board and their RL damage-control experience.
(B) Each ship has a 1944 USN-level damage-control crew on board.

And, as a final question, would you rather have a Soryu or a Wasp if you had to build a fleet carrier on a budget?

EDIT: Originally this was just about the durability of both carriers but I've now expanded the subject to their general usefulness and how they could have been used if they didn't die their respective deaths, especially off Guadalcanal.

 

[CV12Hornet]

Soryu was doomed by her lone bomb hit regardless of whether she was refueling and rearming; the bomb penetrated deep enough to take out her boilers and shatter her steam lines. Dead in the water and with no power, she was done.

Similarly, Wasp was not only hit in the vicinity of her forward gas tanks and magazines, and thus probably would've gone up in a fireball anyway, but three torpedoes was well beyond what she was designed to survive. She lacked a TDS, after all, and simply didn't have the reserve buoyancy, especially once she got low enough in the water and water started flowing into the one torpedo that had porpoised out of the water and hit her above the waterline.

Judging what they would have survived is tricky because as I alluded to, shot placement matters a lot, and Wasp had no sisters to judge in comparison. For Soryu, we have Hiryu and the Unryu class.

Hiryu ate 4 1000-lb bombs and was rapidly set aflame.

Unryu took two torpedo hits, one to the generator room that promptly flooded the boiler rooms, and another to her forward magazines. Ka-boom.

Katsuragi ate a 2000-lb bomb. Miraculously, the bomb detonated high enough in the ship that although the flight deck was wrecked she was still sufficiently operable to act as a repatriation ferry post-war.

Amagi took the most punishment and survived. Multiple near-misses, a 500-lb bomb, a 2000-lb bomb, and a 5" rocket wrecked her flight deck, perforated her hull below the waterline, and compromising her amidships structural integrity below the lower hanger deck. This was survivable, though in the event the crew abandoned ship and progressive flooding might have eventually done her in had the Americans not come back to finish the job. Further bomb hits and near-misses accelerated progressive flooding and she eventually sank.

Note that Amagi and Katsuragi both benefited from sitting at port with no fuel, planes, or ammunition aboard. Katsuragi might have still survived were she at sea and still trying to fight; it's hard to imagine Amagi surviving the first attack in such a situation.

 

[HMS Warspite]

Soryu was doomed by her lone bomb hit regardless of whether she was refueling and rearming; the bomb penetrated deep enough to take out her boilers and shatter her steam lines. Dead in the water and with no power, she was done.

Similarly, Wasp was not only hit in the vicinity of her forward gas tanks and magazines, and thus probably would've gone up in a fireball anyway, but three torpedoes was well beyond what she was designed to survive. She lacked a TDS, after all, and simply didn't have the reserve buoyancy, especially once she got low enough in the water and water started flowing into the one torpedo that had porpoised out of the water and hit her above the waterline.

Judging what they would have survived is tricky because as I alluded to, shot placement matters a lot, and Wasp had no sisters to judge in comparison. For Soryu, we have Hiryu and the Unryu class.

Hiryu ate 4 1000-lb bombs and was rapidly set aflame.

Unryu took two torpedo hits, one to the generator room that promptly flooded the boiler rooms, and another to her forward magazines. Ka-boom.

Katsuragi ate a 2000-lb bomb. Miraculously, the bomb detonated high enough in the ship that although the flight deck was wrecked she was still sufficiently operable to act as a repatriation ferry post-war.

Amagi took the most punishment and survived. Multiple near-misses, a 500-lb bomb, a 2000-lb bomb, and a 5" rocket wrecked her flight deck, perforated her hull below the waterline, and compromising her amidships structural integrity below the lower hanger deck. This was survivable, though in the event the crew abandoned ship and progressive flooding might have eventually done her in had the Americans not come back to finish the job. Further bomb hits and near-misses accelerated progressive flooding and she eventually sank.

Note that Amagi and Katsuragi both benefited from sitting at port with no fuel, planes, or ammunition aboard. Katsuragi might have still survived were she at sea and still trying to fight; it's hard to imagine Amagi surviving the first attack in such a situation.

Actually Soryu took 3 bombs from VB-3 Squadron (one exploding in the lower hangar, two exploding in the upper hangar, admids fueled and armed strikeplanes ready for the attack on the detected USN ships , just waiting to get on the flightdeck, after the Midway Strike and CAP fighters had returned.) Damage was severe and the exploding aircraft and ordonance, did not help either, resulting in large fires getting out of control rapidly. As in USS Wasp the ship did not sink and showed no signs of flooding either, but she was finished as a fighting ship anyway. This was primarily due to the damage being done from above the waterline, leaving the hull as such intact, with no holes in it under the waterline, unlike USS Wasp which had been struck by torpedoes doing structural damage to the hull, though had her internal watertightness maintained by damagecontrol.

My guess is you shifted Akagi for the Soryu somehow, as the damagereport of Akagi matches your writing. (Shattered Swords and Midway by Fuchida)

BTW USN damagecontrol often could keep a stricken ship affloat, though not in a serviceable condition, due to secondary damage to fighting systems, as is seen basically on USS Yorktown, USS Hornet and USS Franklin to name a few. IJN damagecontrol left a lot to be desired and was completely inadequate to do the same job, mostly due to lack of training and partly due to Japanese culture to focus on the offensive, rather than the defensive. Also note the Royal Navy too had a learningproces in damagecontrol, though around 1942 the rearly war mistakes had been learned and corrected. (Sinking of HMS Courageous, and Ark Royal technically could have been avoided with proper damagecontrol at the time.)

 

[PorkNuggets]

Relevant Video on the topic.

 

[TxAggie]

These are two of the if not the most thinly protected fleet carriers in WWII, so they are always going to be in trouble when they start taking fire.

Wasp was the size of a cruiser and had no armor to speak of, and it ate 3 torpedoes. That would probably be a mortal hit for anything smaller than a battleship, and Wasp was not built to buck that trend. If it was bombed, it would probably have suffered a similar fate as Soryu, having next to no deck armor means that bombs are going to punch through to places you really don't want bombs at. Any one bomb hitting has a decent chance of being fatal. If it ate 3 like Soryu did, then that's pretty much the end of the show.

Vica versa, Soryu would have died about like Wasp did if it took torpedoes. It might have been able to limp off after one hit if that torpedo didn't ignite anything belowdecks, but staying afloat through multiple torpedo hits is a lot to ask for a 15,000 ton ship, and every new torpedo that hits has a high probability of igniting a kaboom.

If either one came within gunfire range of an enemy fleet, it would be like shooting a 9mm at a soda can. Those shots are going through-and-through. It may actually be to their advantage if they just took one stray hit from an enemy ship - if it just zipped through an empty hanger, those carriers are remaining 100% combat functional. Any sort of concentrated fire though would quickly do them in.

 

[Cryptic]

As a side note, empty fuel lines were not always that empty as there was a big potential for flammable fumes leaking from shattered lines etc.

US carriers had systems that drained the fuel lines, but also injected flame and fume suppressing carbon dioxide into them. The IJN never adopted the practice-and the results could add towards a catastrophe.

 

[Kantai Kessen]

These are two of the if not the most thinly protected fleet carriers in WWII, so they are always going to be in trouble when they start taking fire.

Wasp was the size of a cruiser and had no armor to speak of, and it ate 3 torpedoes. That would probably be a mortal hit for anything smaller than a battleship, and Wasp was not built to buck that trend. If it was bombed, it would probably have suffered a similar fate as Soryu, having next to no deck armor means that bombs are going to punch through to places you really don't want bombs at. Any one bomb hitting has a decent chance of being fatal. If it ate 3 like Soryu did, then that's pretty much the end of the show.

Vica versa, Soryu would have died about like Wasp did if it took torpedoes. It might have been able to limp off after one hit if that torpedo didn't ignite anything belowdecks, but staying afloat through multiple torpedo hits is a lot to ask for a 15,000 ton ship, and every new torpedo that hits has a high probability of igniting a kaboom.

If either one came within gunfire range of an enemy fleet, it would be like shooting a 9mm at a soda can. Those shots are going through-and-through. It may actually be to their advantage if they just took one stray hit from an enemy ship - if it just zipped through an empty hanger, those carriers are remaining 100% combat functional. Any sort of concentrated fire though would quickly do them in.

I believe I once heard that Wasp had alternating boiler and engine rooms, so that if she took a torpedo hit and only suffered flooding (big if), she actually had a better chance of surviving than a Yorktown.

However, Wasp is slow (29.5 knots) and probably cannot outmaneuver or outrun torpedoes. Whereas Soryu can - so less likely to sccumb?

 

[Kantai Kessen]

As a side note, empty fuel lines were not always that empty as there was a big potential for flammable fumes leaking from shattered lines etc.

US carriers had systems that drained the fuel lines, but also injected flame and fume suppressing carbon dioxide into them. The IJN never adopted the practice-and the results could add towards a catastrophe.

Good point. Did that help to do in Taiho?

 

[Kantai Kessen]

Actually Soryu took 3 bombs from VB-3 Squadron (one exploding in the lower hangar, two exploding in the upper hangar, admids fueled and armed strikeplanes ready for the attack on the detected USN ships , just waiting to get on the flightdeck, after the Midway Strike and CAP fighters had returned.) Damage was severe and the exploding aircraft and ordonance, did not help either, resulting in large fires getting out of control rapidly. As in USS Wasp the ship did not sink and showed no signs of flooding either, but she was finished as a fighting ship anyway. This was primarily due to the damage being done from above the waterline, leaving the hull as such intact, with no holes in it under the waterline, unlike USS Wasp which had been struck by torpedoes doing structural damage to the hull, though had her internal watertightness maintained by damagecontrol.

My guess is you shifted Akagi for the Soryu somehow, as the damagereport of Akagi matches your writing. (Shattered Swords and Midway by Fuchida)

BTW USN damagecontrol often could keep a stricken ship affloat, though not in a serviceable condition, due to secondary damage to fighting systems, as is seen basically on USS Yorktown, USS Hornet and USS Franklin to name a few. IJN damagecontrol left a lot to be desired and was completely inadequate to do the same job, mostly due to lack of training and partly due to Japanese culture to focus on the offensive, rather than the defensive. Also note the Royal Navy too had a learningproces in damagecontrol, though around 1942 the rearly war mistakes had been learned and corrected. (Sinking of HMS Courageous, and Ark Royal technically could have been avoided with proper damagecontrol at the time.)

Soryu did take the severe engine hit.

 

[HMS Warspite]

Soryu did take the severe engine hit.

Not directly, but as a result of burning fuel and secondary explosions her engines failed quickly. Normally ships do not carry propulsion in their hangardecks.

 

[Kantai Kessen]

Not directly, but as a result of burning fuel and secondary explosions her engines failed quickly. Normally ships do not carry propulsion in their hangardecks.

According to Nihon Kaigun: http://www.combinedfleet.com/soryu.htm

- 1025-1026 While continuing launch preparations against a sighted enemy carrier, attacked by thirteen enemy dive bombers. Two direct bomb hits are sustained, one on the forward elevator, the other aft the second elevator, setting off furious fires and induced explosions among the armed and fueled aircraft.
- 1029 A 1,000 pound bomb hit amidships abreast the stacks, the bomb or its blast effects apparently penetrating to explode on the lower hangar deck starting fires amid the aircraft returned from the Midway strike. The explosion also damaged the upper section of the boiler rooms and shattered steam lines. With the main supply line shattered, steam to drive the turbines escaped. SORYU's engines abruptly ceased and she lost all propulsion on both sides. Plane-guard destroyer ISOKAZE near-missed off fantail.

This seems to indicate that the engines were taken out by a direct hit. You are right though that she took 3 bomb hits.

That was a 1,000-pound weapon, though. Makes me wonder: if Soryu only took that bomb hit with no refuelling or rearming airplanes on board, how would she be salvaged? The damage does not seem to be fatal in of itself, and only involves loss of propulsion. I think power to the weapons should be around. Towing her, perhaps?

 

[McPherson]

However, Wasp is slow (29.5 knots) and probably cannot outmaneuver or outrun torpedoes. Whereas Soryu can - so less likely to sccumb?

Outrun, no, but turn to avoid? Entirely possible. USS Wasp was making a speed run into the wind to launch what was apparently a CAP and the lookout watch did not see the the torpedo tracks of fish sent by I-19 at her in time. I blame Ghormley for not following doctrine and keeping the CTFs he had moving around so that the Japanese could not establish a route schedule and set up ambushes. He, meaning his staff tended to route them predictably. The other idiot was RADM Leigh Noyes CTF commander, who could have ignored Ghormley's instructions and danced around the predictable troop convoy route to Guadalcanal that USS Wasp, and USS Hornet and USS North Carolina followed. The Japanese I and R boats were shoaling like barracudas near San Cristobel Island and so you get what you got.

Preventable stupidity I believe is what it is called. Noyes was canned, and Ghormley was relieved. Noyes for incompetence and Ghormley for going nuts.

 

[Kantai Kessen]

Outrun, no, but turn to avoid? Entirely possible. USS Wasp was making a speed run into the wind to launch what was apparently a CAP and the lookout watch did not see the the torpedo tracks of fish sent by I-19 at her in time. I blame Ghormley for not following doctrine and keeping the CTFs he had moving around so that the Japanese could not establish a route schedule and set up ambushes. He, meaning his staff tended to route them predictably. The other idiot was RADM Leigh Noyes CTF commander, who could have ignored Ghormley's instructions and danced around the predictable troop convoy route to Guadalcanal that USS Wasp, and USS Hornet and USS North Carolina followed. The Japanese I and R boats were shoaling like barracudas near San Cristobel Island and so you get what you got.

Preventable stupidity I believe is what it is called. Noyes was canned, and Ghormley was relieved. Noyes for incompetence and Ghormley for going nuts.

If Wasp was not intercepted, she and NC would have been at Santa Cruz. Do you think that is enough to allow a US victory?

 

[Kantai Kessen]

Actually Soryu took 3 bombs from VB-3 Squadron (one exploding in the lower hangar, two exploding in the upper hangar, admids fueled and armed strikeplanes ready for the attack on the detected USN ships , just waiting to get on the flightdeck, after the Midway Strike and CAP fighters had returned.) Damage was severe and the exploding aircraft and ordonance, did not help either, resulting in large fires getting out of control rapidly. As in USS Wasp the ship did not sink and showed no signs of flooding either, but she was finished as a fighting ship anyway. This was primarily due to the damage being done from above the waterline, leaving the hull as such intact, with no holes in it under the waterline, unlike USS Wasp which had been struck by torpedoes doing structural damage to the hull, though had her internal watertightness maintained by damagecontrol.

My guess is you shifted Akagi for the Soryu somehow, as the damagereport of Akagi matches your writing. (Shattered Swords and Midway by Fuchida)

BTW USN damagecontrol often could keep a stricken ship affloat, though not in a serviceable condition, due to secondary damage to fighting systems, as is seen basically on USS Yorktown, USS Hornet and USS Franklin to name a few. IJN damagecontrol left a lot to be desired and was completely inadequate to do the same job, mostly due to lack of training and partly due to Japanese culture to focus on the offensive, rather than the defensive. Also note the Royal Navy too had a learningproces in damagecontrol, though around 1942 the rearly war mistakes had been learned and corrected. (Sinking of HMS Courageous, and Ark Royal technically could have been avoided with proper damagecontrol at the time.)

The thing is, IJN doctrine was to arm torpedo bombers in the hangar bay and dive bombers on the flight deck. So if Yorktown's bombers are a few minutes late and Soryu, having fuelled her Vals, has them on deck when they appear, could she survive?

 

[McPherson]

If Wasp was not intercepted, she and NC would have been at Santa Cruz. Do you think that is enough to allow a US victory?

Not likely. The fighter directors running intercept were new to their jobs and mostly incompetent, Miles Browning had not been fed to the sharks, Kincaid made serious almost fatal recon mistakes, and Halsey was running the shore op and he was always an inept fleet handler. One needed FLETCHER more than another aircraft carrier or battleship.

 

[Kantai Kessen]

Not likely. The fighter directors running intercept were new to their jobs and mostly incompetent, Miles Browning had not been fed to the sharks, Kincaid made serious almost fatal recon mistakes, and Halsey was running the shore op and he was always an inept fleet handler. One needed FLETCHER more than another aircraft carrier or battleship.

Well, then do you think we could kill Wasp instead of Hornet? Better trade.

 

[McPherson]

Well, then do you think we could kill Wasp instead of Hornet? Better trade.

Relieve Noyes, relieve Ghormley, promote Sherman to Noyes slot. Send Browning to the Naval Disciplinary Barracks, preferably as an inmate, and send Barbey or have Lee slotted to handle SOPAC until Fletcher recovers and then send HIM to be SOPAC. At that point, I think Watchtower would be in a lot better shape. There could even be a chance that Santa Cruz turns out alright.

 

[Dorknought]

And, as a final question, would you rather have a Soryu or a Wasp if you had to build a fleet carrier on a budget?

Perhaps something like Saipan instead: https://en.wikipedia.org/wiki/Saipan-class_aircraft_carrier
The HMS Colossus class are also in the same displacement range.

 

[Kantai Kessen]

Perhaps something like Saipan instead: https://en.wikipedia.org/wiki/Saipan-class_aircraft_carrier
The HMS Colossus class are also in the same displacement range.

Saipan seems good, although her air group is a bit small. By 1944 IJN standards though it seems fine (they were planning to equip the Unryus with only 48 planes apiece anyway). No heavy AA either, which is a bit of a deficiency - while Soryu very much had twelve 5" guns, as IJN carrier defence centred on the flattops manoeuvring and protecting themselves from enemy planes

I think the RN Colossus/Majestic type is too slow for fleet operations. Just 25 knots is not good. They are also not built to military standard and thus will not be as durable in a combat situation.

For myself, I'd probably take a Soryu over a Wasp. At least she can run away if an enemy carrier group or some fast battleships appears on the horizon.

 

[McPherson]

Saipan seems good, although her air group is a bit small. By 1944 IJN standards though it seems fine (they were planning to equip the Unryus with only 48 planes apiece anyway). No heavy AA either, which is a bit of a deficiency - while Soryu very much had twelve 5" guns, as IJN carrier defence centred on the flattops manoeuvring and protecting themselves from enemy planes

I think the RN Colossus/Majestic type is too slow for fleet operations. Just 25 knots is not good. They are also not built to military standard and thus will not be as durable in a combat situation.

For myself, I'd probably take a Soryu over a Wasp. At least she can run away if an enemy carrier group or some fast battleships appears on the horizon.

Some things.

The Wasp class has a superior fire main system. It did not fail her until the flooding knocked it out.

The elevators / lifts on the USS Wasp do not descend below the flight deck and bottom below out in a bilge space. One of the reasons Japanese aircraft carriers exploded and blow torched was because these elevator wells acted as natural collection points for gasoline when fuel lines ruptured. The vapors given off resulted in the creation of what we know now as a Fuel / Air / Explosive or FAE detonation event. This killed HIJMS Taiho. HIJMS Shōkaku, HIJMS Akagi and probably did in Jun yo as well. Numerous other Japanese flattops often simply blowtorched because of it.

USS Wasp had superior AAA, and a better air group and fighter director facilities (Pry Fly). She had a better rudder steer and better torpedo defense in her compartmentation than Soryu. What killed her was clearly mishandling and bad luck, not actual performance metrics. She died hard. Soryu went down like a punk. Wasp was tougher than she looked.

And I maintain, if she had been properly bulged (1938-1939) in a refit, after the Japanese LNT walkout, she would have done better on that 15 September 1942 despite those three torpedoes.

Remember, the Wasp made two club runs to Malta as was, and not a scratch. She was able to DODGE and weave. This also showed two things; The Luftwaffe was incompetent as to anti-ship compared to the IJNAS and the KM U-boat arm was also a clown club.