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Depth charges ever used against surface ships?

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I got thinking about the attacks on the Tirpitz, how conventional CV dropped bombs were not powerful enough to do much damage and with torpedo netting the Torps would not get through. The Tallboy bombs were eventually needed which was also a hassle, so question is why not use depth charges to sink down the ship and sink it that was since the keel armor was typically weaker right?

I know there was a group of “dam busters” that would fly low and get explosives be drums to bounce across the water to break up dams since they could bounce over the nets. But not sure if they would have been able to do it with Tirpitz. But if you saturated the area Tirpitz was in with enough depth charges set to go off at certain hour so you could get good sized under water shock wave could that have worked? The Norwegian Fyord where Tirpitz was anchored could not have been that deep as to have prevented the ship from feeling the effects of such blasts or was it deep enough?

The Royal Navy Migdget subs attempted to use couple sea mines below Tirpitz which made me wonder about simply sending out CV few hundred Bombers with the depth charges. After all even if deck armor and belt armor was thick eneough to resist bombs, its far less likely that keel armor could be as strong?

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17 minutes ago, Admiral_Thrawn_1 said:

I got thinking about the attacks on the Tirpitz, how conventional CV dropped bombs were not powerful enough to do much damage and with torpedo netting the Torps would not get through. The Tallboy bombs were eventually needed which was also a hassle, so question is why not use depth charges to sink down the ship and sink it that was since the keel armor was typically weaker right?

I know there was a group of “dam busters” that would fly low and get explosives be drums to bounce across the water to break up dams since they could bounce over the nets. But not sure if they would have been able to do it with Tirpitz. But if you saturated the area Tirpitz was in with enough depth charges set to go off at certain hour so you could get good sized under water shock wave could that have worked? The Norwegian Fyord where Tirpitz was anchored could not have been that deep as to have prevented the ship from feeling the effects of such blasts or was it deep enough?

The Royal Navy Migdget subs attempted to use couple sea mines below Tirpitz which made me wonder about simply sending out CV few hundred Bombers with the depth charges. After all even if deck armor and belt armor was thick eneough to resist bombs, its far less likely that keel armor could be as strong?

Um....the Keel is the spine of the ship and what could be considered "final generation" battleships had Keels that routinely resisted saturation hits by submarine and airborne torpedoes, sinking only when flooding overwhelmed damage control parties. There's just too much armor holding those ships together for them to fall victim to a backbreaker torpedo strike.

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I am not really sure if I can answer the question in the OP, however I do have an answer on the question in the title.

The German Destroyer Friedrich Ihn found a lone Sovjet freighter in 1942, and attempted to sink it. Since the Torpedoes failed (something, something torpedo reliability) it was decided to use the deoth charges. Driving backwards to the freighter, dropping the depth charges very closely and accelerating quickly enough to not getting hit by the explosion. The freighter sank.

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9 minutes ago, TornadoADV said:

Um....the Keel is the spine of the ship and what could be considered "final generation" battleships had Keels that routinely resisted saturation hits by submarine and airborne torpedoes, sinking only when flooding overwhelmed damage control parties. There's just too much armor holding those ships together for them to fall victim to a backbreaker torpedo strike.

That is optimal for a ship to resist even explosives detonated under the ship, but still wondered if some did not have such protection.

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To really do the serious damage you are talking about you would need to get the depth charges under the ship. Not an easy task.

Taking a page from WOWS, the Brits might have had more luck dropping waves of incendiaries and HE.  Blanketing the area multiple times during the day. Keeping the firefighting crews off the decks.

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They were often used in coastal warfare by PT/MTB/MGB against armored barges but not against ships.

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3 hours ago, Admiral_Thrawn_1 said:

I got thinking about the attacks on the Tirpitz, how conventional CV dropped bombs were not powerful enough to do much damage and with torpedo netting the Torps would not get through. The Tallboy bombs were eventually needed which was also a hassle, so question is why not use depth charges to sink down the ship and sink it that was since the keel armor was typically weaker right?

I know there was a group of “dam busters” that would fly low and get explosives be drums to bounce across the water to break up dams since they could bounce over the nets. But not sure if they would have been able to do it with Tirpitz. But if you saturated the area Tirpitz was in with enough depth charges set to go off at certain hour so you could get good sized under water shock wave could that have worked? The Norwegian Fyord where Tirpitz was anchored could not have been that deep as to have prevented the ship from feeling the effects of such blasts or was it deep enough?

The Royal Navy Migdget subs attempted to use couple sea mines below Tirpitz which made me wonder about simply sending out CV few hundred Bombers with the depth charges. After all even if deck armor and belt armor was thick eneough to resist bombs, its far less likely that keel armor could be as strong?

Not conveniently "depth charges" but... when Billy Mitchell tried to prove the power of naval aviation in 1921 by bombing the German Battleship Ostfriesland, the underwater bomb detonations proved the most damaging.  " Five 600 lb bombs found their mark, but little damage was done to the ship's topside. The bombs that nearly missed the ship, however, had done significant underwater damage to the hull, which allowed some flooding and created a list of five degrees to port and three additional feet of draft at the stern. 

"Early on the morning of 21 July, the fifth wave of bombers began their attack. At 08:52, the first Army bomber dropped a 1,000 lb (450 kg) bomb that hit the ship; four more bombers followed and scored two further hits. Inspectors again went aboard Ostfriesland following the fifth attack and noted that the hits had not seriously damaged the ship, though one had created a large hole on her starboard side that allowed further flooding. By noon, she was down five feet at the stern and one foot at the bow. At 12:19, the next attack wave, equipped with 2,000 lb (910 kg) bombs, struck. Six bombs were dropped, none of which hit, though three detonated very close to the hull. At 12:30, Ostfriesland began to sink rapidly by the stern and the list to port increased dramatically. At 12:40, the ship rolled over and sank." - https://en.wikipedia.org/wiki/SMS_Ostfriesland#US_bombing_target

1024px-SMS_Ostfriesland_bomb_exploding_n

Edited by Royeaux
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13 minutes ago, Royeaux said:

Not conveniently "depth charges" but... when Billy Mitchell tried to prove the power of naval aviation in 1921 by bombing the German Battleship Ostfriesland, the underwater bomb detonations proved the most damaging.  " Five 600 lb bombs found their mark, but little damage was done to the ship's topside. The bombs that nearly missed the ship, however, had done significant underwater damage to the hull, which allowed some flooding and created a list of five degrees to port and three additional feet of draft at the stern. 

"Early on the morning of 21 July, the fifth wave of bombers began their attack. At 08:52, the first Army bomber dropped a 1,000 lb (450 kg) bomb that hit the ship; four more bombers followed and scored two further hits. Inspectors again went aboard Ostfriesland following the fifth attack and noted that the hits had not seriously damaged the ship, though one had created a large hole on her starboard side that allowed further flooding. By noon, she was down five feet at the stern and one foot at the bow. At 12:19, the next attack wave, equipped with 2,000 lb (910 kg) bombs, struck. Six bombs were dropped, none of which hit, though three detonated very close to the hull. At 12:30, Ostfriesland began to sink rapidly by the stern and the list to port increased dramatically. At 12:40, the ship rolled over and sank." - https://en.wikipedia.org/wiki/SMS_Ostfriesland#US_bombing_target

1024px-SMS_Ostfriesland_bomb_exploding_n

Probably why most naval officers dismissed the power of CVs at that point since they figured that a ship under way would been less vulnerable to attack and if little damage was done to the superstructure, decks, or belt armor they may have felt the test was not truely representative of the power of naval aviation.

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12 hours ago, Royeaux said:

Not conveniently "depth charges" but... when Billy Mitchell tried to prove the power of naval aviation in 1921 by bombing the German Battleship Ostfriesland, the underwater bomb detonations proved the most damaging.  " Five 600 lb bombs found their mark, but little damage was done to the ship's topside. The bombs that nearly missed the ship, however, had done significant underwater damage to the hull, which allowed some flooding and created a list of five degrees to port and three additional feet of draft at the stern. 

"Early on the morning of 21 July, the fifth wave of bombers began their attack. At 08:52, the first Army bomber dropped a 1,000 lb (450 kg) bomb that hit the ship; four more bombers followed and scored two further hits. Inspectors again went aboard Ostfriesland following the fifth attack and noted that the hits had not seriously damaged the ship, though one had created a large hole on her starboard side that allowed further flooding. By noon, she was down five feet at the stern and one foot at the bow. At 12:19, the next attack wave, equipped with 2,000 lb (910 kg) bombs, struck. Six bombs were dropped, none of which hit, though three detonated very close to the hull. At 12:30, Ostfriesland began to sink rapidly by the stern and the list to port increased dramatically. At 12:40, the ship rolled over and sank." - https://en.wikipedia.org/wiki/SMS_Ostfriesland#US_bombing_target

1024px-SMS_Ostfriesland_bomb_exploding_n

 

12 hours ago, Admiral_Thrawn_1 said:

Probably why most naval officers dismissed the power of CVs at that point since they figured that a ship under way would been less vulnerable to attack and if little damage was done to the superstructure, decks, or belt armor they may have felt the test was not truely representative of the power of naval aviation.

 

guess I'll play devil's advocate......

Ostfriesland was one of the first classes of Dreadnought. It had already seen hard service in WW1. With the war ending roughly 3 years before, I wonder materially, what condition the ship was in? For those three years post war, it had been in Allied hands. How well was it maintained in Allied hands?

As I said, it being a first generation Dreadnought, there were several developments in weaponry that were either not thought of or considered insignificant at the time of their design. One of those being the airplane.

By WW2, most of the Dreadnoughts that had existed before WW1 had been refitted and upgraded in armor, torpedo bulges, etc. A depth charge going off next to a Dreadnought, or even a more modern BB is going to rattle the ship, maybe pop a seam/rivet or two. But it isn't going to sink it. They are simply too well built and armored.


The problem is that Depth charges were designed to sink submarines whose hull was maybe an inch or so thick. Factor in the depth the submarine was operating at, a burst seam is going to let in quite a bit of water. Even then, it could take a barrage of several hours before a submarine might be damaged enough to surface.

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I know that during the Battle off Samar some of Taffy 3's aircraft had depth charges equiped when they went into battle, so I guess that could count?

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Some example Depth Charges and the amount of explosives they carried.

USN Mark 6 and 7 Depth Charges: 300 and 600 lbs of TNT respectively (136, 272 kg).  Common issue DCs of the USN for WWII.

Royal Navy Mark VII 290 lbs (132 kg) of TNT.  "The standard DC of the first three years of World War II."

The Mark X was a weird one meant to be launched from a 533mm torpedo tube and then slowly sinks to attack the submarine.  Had a yooge amount of explosives for a DC, 3050 lbs (1383 kg) of TNT.

"Intended for launching from a 21 inch (53.3 cm) torpedo tube. The slow sinking speed of the Mark X was so that the launching ship could get clear of the explosion.

In 1943, the Mark X* was introduced. This had a faster sinking and deeper depth setting intended to combat the deeper diving U-boats that were becoming more prevalent.

In 1945, the even faster sinking Mark X** was developed for use against the newer, deeper diving U-boats, but this version was not introduced into service, as the ahead throwing weapons had obsoleted it."

I am unsure how commonly fielded the Mark X DCs were.

 

IJN (they put very little effort into ASW until it was too late).  The standard was the Type 95 for WWII.  Depending on the variant of the Type 95, amount of explosives carried varied between 220 lbs (100 kg) to 324 lbs (137 kg).

 

Let's compare the amount of explosives to some standard torpedoes out there during WWII:

 

USN

Mark 15:  3438 lbs of TNT, later 3841 lbs (1742 kg).  Standard USN DD and Atlanta-class CL torpedoes of WWII.

RN

Mark IX:  722-750 lbs (327-340 kg) of TNT.  Some got 805 lbs (365 kg) of Torpex.

Torpex?

Spoiler

 

"The earliest weapons used wet gun-cotton. Just prior to World War I, this was replaced with TNT. Torpex (TPX) was introduced in the Fall of 1942. In the late 1940s Torpex was replaced by HBX, then H-6 in the 1960s and by PBX in the 1970s.

Approximately 1.9 lbs. (0.9 kg) of wet gun-cotton is equivalent to 1.0 lbs. (0.45 kg) of TNT.

Torpex is a mixture of 37-41% TNT, 41-45% RDX (cyclonite, cyclomethylene trinitramine) and 18% aluminum. HBX and H-6 are also TNT based with additives to increase their explosive power or increase their stability.

Torpex is attractive because of the increased explosive energy and higher detonation velocity of RDX as compared to TNT and the prolongation of the pressure wave by the aluminum. On a weight basis, Torpex is conservatively estimated to be about 50% more effective than TNT as an underwater explosive against ships. However, Torpex is more sensitive than TNT and RDX is expensive and difficult to make safely."

 

 

IJN Long Lances we also all know carried a lot more explosives.

The amount of explosives carried by torpedoes dwarfs that of Depth Charges.  They have to deal with armor, torpedo bulges, etc.  Depth Charges don't, they're after fragile submarines.  Not to mention getting so close to drop Depth Charges.  You got Torpedoes which not only pack significantly higher power, but a safer engagement range.

Edited by HazeGrayUnderway

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