Depth Charging Submarines

[casdave]

We were doing som A/S mortar firings as part of operational work up back in the 1970’s,

Sytem was pretty old fashioned even then, you shoot three mortar rounds from the launcher on the stern, these fly over the top pf the masts and all and land in the sea front of the ship, at ranges from around 400 yards to about 1000 yards.

Each projectile weighed about 400lbs- so thats 1200 lbs of get the fuck outa my ocean being launched in every salvo.

Whenever you have live firings, you have clear fire safety zones - we had a sub that had encroached on the edge of the zone, it was also doing operational work up, but it should have been further away - the shockwave of our mortars took paint off the inside of the sub, which was well over a mile away, I really really would not want to be in a sub with these things exploding anywhere within 100yards.

The problem with the tv and film shows is that the true ranges of weapons does not make for good looking action pictures, the depth charge that is part of the film makers mock up which explodes almost next to the sub would certainly destroy it, a depth charge within 50 yards would probably sink it, I am willing to bet that 1200 pounds of bang in an incompressible medium would kill a sub, folk do not understand the sheer power of maritime weapons, nor the scale of space that is a major component of maritime warfare.

A/S torpedos are small compared to anti shipping torpedos which can be 32 feet long, those A/S torps do not need to be big and they do not need to make direct contact either.

Gaining depth does add another dimension of uncertainty to any attack solution, this is a 3 dimensional war, a sub can travel away in any direction and at any operational depth all f which makes it harder to find.

The attack range og the sub will place it a good distance from a surface vessel, 5 miles or more if needed, by the time short range weapons such as depth charges and mortars are able to engage, the sub will have an opportunity to make off - it takes some time for an a/s vessel to put itself into position, especially with a plethora of dodgy contacts that usually need to be eliminated.

[Whack-a-Mole]

@Paul_in_Qatar

Remember the great game SIlent Service II? According to the manual (so it must be true), American subs in WWII could dive to a deeper depth than the Japanese knew. So the Japanese depth charges went to X depth, but the American sub could hide at Y depth. All the charges were too shallow.

Or not; I am no expert.

I remember the game and played it but do not remember that part. Maybe I didn’t RTFM back then.

Anyway, sounds dubious to me. Assuming the Japanese had active sonar then all it would take is for an ASW ship to ping a sub at X-depth for them to go, “Hey! That thing is deeper than we thought it could be! Set weapons for X-depth!” After a few such reports they’d know it wasn’t a fluke and would be common knowledge in the ASW community.

[Tim_T-Bonham.net]

@Sailboat

In WWII, sonar (I think we’re talking about active sonar mainly, the kind that “pings”) was blind right in front of the ship, and both sides knew it. Standard tactics, in addition to diving, were to maneuver at the last moment, just before the depth-charging vessel passed overhead, in an attempt to make the problem of hitting the sub harder by enlarging the possible area the sub could be in.

Quite true, and this blind spot gave rise to a very effective tactic when there were 2 anti-submarine ships available: one ship stands off a ways, and maintains contact on the submarine with its’ sonar. The other one passes over the sub and drops depth charges. The sub moves when it is in the blind spot of the depth-charging ship, but the other ship a ways off still has the sub in its sonar, and can tell the depth-charging ship where the sub moved to, and where to try again.

This tactic was very effective, once American shipyards started producing enough ships that you could use 2 escort ships to hunt down a submarine, without leaving the convoy too low on defensive ships.

[Tim_T-Bonham.net]

@Whack-a-Mole

Anyway, sounds dubious to me. Assuming the Japanese had active sonar then all it would take is for an ASW ship to ping a sub at X-depth for them to go, “Hey! That thing is deeper than we thought it could be! Set weapons for X-depth!” After a few such reports they’d know it wasn’t a fluke and would be common knowledge in the ASW community.

I believe the sonar used during most of WWII gave only a direction to the target, without giving a depth. So you still had to guess at the depth of the submarine. Some expert, experienced sonar officers could tell from the ‘sound’ of the sonar the approximate depth, but it was still mainly a guess.

[davekhps]

Here’s a question-- did World War I and II submariners know about the thermocline and how it affected sonar?

I know Cold Warriors did, but I’m just wondering how advanced the understanding of the undersea “environment” was in the early days of submarine warfare (and how quickly it advanced).

Off-topic, but related: I’m still peeved that none of the otherwise-great modern submarine movies (Hunt for Red October, Crimson Tide, etc.) ever featured what is truly the coolest aspect of modern submarine warfare, namely that torpedoes are wire-guided, i.e. they’re not just dumb point-and-shoot or even simple homing weapons of yore.

Always struck me as like making* Top Gun* with prop planes.

[GreasyJack]

@Paul_in_Qatar

Remember the great game SIlent Service II? According to the manual (so it must be true), American subs in WWII could dive to a deeper depth than the Japanese knew. So the Japanese depth charges went to X depth, but the American sub could hide at Y depth. All the charges were too shallow.

Or not; I am no expert.

I seem to remember that being an issue early in the war in the original Silent Hunter as well. Bascially as I understood it they couldn’t physically set the depth charges to the crush depth of some of the US submarines. But I think even it being corrobarated by two video games still doesn’t necessarilly mean it’s true.

[GreasyJack]

@davekhps

Here’s a question-- did World War I and II submariners know about the thermocline and how it affected sonar?

Also again drawing from video game knowledge, later in the war the US subs got “bathythermographs” which plotted the water temperature as the sub decended. I’ve actually got a real cite for this one, though:

http://www.fleetsubmarine.com/ss-224-photo.html

See “control room 4”

[Kobal2]

@davekhps

Here’s a question-- did World War I and II submariners know about the thermocline and how it affected sonar?

I know Cold Warriors did, but I’m just wondering how advanced the understanding of the undersea “environment” was in the early days of submarine warfare (and how quickly it advanced).

Off-topic, but related: I’m still peeved that none of the otherwise-great modern submarine movies (Hunt for Red October, Crimson Tide, etc.) ever featured what is truly the coolest aspect of modern submarine warfare, namely that torpedoes are wire-guided, i.e. they’re not just dumb point-and-shoot or even simple homing weapons of yore.

Always struck me as like making* Top Gun* with prop planes.

What are you talking about ? Red October certainly did wired torpedoes. How else do you think James Earl Jones blew up that last one before it hit ?

Of course, the whole “head straight for the torp so you blow past it before it can arm” bit doesn’t really work when the other sub’s torp officer is on the ball and makes the torpedo do a 180… But then again, it’s not alltogether uncommon to cut the wires on purpose when you need manoeuvrability, to cut the wires accidentally when turning too fast, or to sever them on purpose when you want to reload that tube ASAP. So my disbelief still hangs by a thread there.

On the other hand, Crimson Tide had THE scene that irked me the most : the sonar display looking like a Hollywood radar screen (itself so far removed from an *actual *radar screen, it’s not even funny anymore)

[Snnipe_70E]

@Paul_in_Qatar

Remember the great game SIlent Service II? According to the manual (so it must be true), American subs in WWII could dive to a deeper depth than the Japanese knew. So the Japanese depth charges went to X depth, but the American sub could hide at Y depth. All the charges were too shallow.

Or not; I am no expert.

The fleet boats were designed for a max depth of 400 feet. But some skippers like Mush Morton and Keth O’Kane made changes to their boats so they could go to 600 feet.
The best method of attacking a sub took three destroyers. One on each side of the sub coasting or going at a slow speed. The third charging up the middle dropping according to the directions of the other two. After the third drops he coasts and listens whild another destroyer makes a run. When a Destroyer is going on a high speed run it can not hear.

there was a book written about a one on one attack and the dificulity of either being sucessful. It was EMENY BELOW.

[robby]

@Kobal2

What are you talking about ? Red October certainly did wired torpedoes. How else do you think James Earl Jones blew up that last one before it hit ?

Except James Earl Jones blew up an air-dropped MK-46 torpedo, which is NOT wire-guided and has no self-destruct capability.

@Kobal2

On the other hand, Crimson Tide had THE scene that irked me the most : the sonar display looking like a Hollywood radar screen (itself so far removed from an *actual *radar screen, it’s not even funny anymore)

Exactly. The whole movie had so many errors in it, but this one was the last straw for me. Particularly when the earlier Hunt for Red October had done so many (but not all) things right.

[Kobal2]

@robby

Except James Earl Jones blew up an air-dropped MK-46 torpedo, which is NOT wire-guided and has no self-destruct capability.

Damn, you’re right. I could have sworn the torp had been launched from the destroyer (which would have been just as silly, of course, but at least the self destruct button would have made *some *semblance of sense.)

[AK84]

Did’nt British Ships carry an atomic depth charge in the cold war? How the hell are you supposed to survive that yourself nev er mind the sub?

[abel29a]

@GreasyJack

I seem to remember that being an issue early in the war in the original Silent Hunter as well. Bascially as I understood it they couldn’t physically set the depth charges to the crush depth of some of the US submarines. But I think even it being corrobarated by two video games still doesn’t necessarilly mean it’s true.

Same thing with British DC versus German Uboats during the early part of the war. The German Uboats routinely went beneath the shipyard guaranteed depths, and the British DC settings did not allow them to be set at that depth. (Or so much research during my SHIII period tells me )

[Icerigger]

Does the Navy even still use the old fashioned Depth Charges you roll off the fantail?

[davekhps]

@Kobal2

Damn, you’re right. I could have sworn the torp had been launched from the destroyer (which would have been just as silly, of course, but at least the self destruct button would have made *some *semblance of sense.)

Yup-- what he said

[Kobal2]

@Icerigger

Does the Navy even still use the old fashioned Depth Charges you roll off the fantail?

Nope. They’ve been replaced by ASROC “missiles”, which are not so much missiles as a kind of rocket propelled sabot that delivers a homing torpedo right on top of a sub’s suspected position.

That being said, antisubmarine warfare is mostly performed by helicopters and airplanes (and, of course, other submarines) these days, since surface vessels are at an even worse disadvantage than they were back in WW2.

[JWT_Kottekoe]

@AK84

Did’nt British Ships carry an atomic depth charge in the cold war? How the hell are you supposed to survive that yourself nev er mind the sub?

I had heard that the P3 Orion antisubmarine war planes that flew out of Moffett Field in Sunnyvale, CA were equipped with nuclear depth charges. I always wondered if that was really true.

[kombatminipig]

@Kobal2

Nope. They’ve been replaced by ASROC “missiles”, which are not so much missiles as a kind of rocket propelled sabot that delivers a homing torpedo right on top of a sub’s suspected position.

That being said, antisubmarine warfare is mostly performed by helicopters and airplanes (and, of course, other submarines) these days, since surface vessels are at an even worse disadvantage than they were back in WW2.

Oh yes. The Swedes are still pretty darn pleased about sinking an aircraft carrier

[Declan]

@AK84

Did’nt British Ships carry an atomic depth charge in the cold war? How the hell are you supposed to survive that yourself nev er mind the sub?

Well picture the soviet sub , either a HK lining up for a shot at the ark royal or a boomer about to unload some nukes of its own on your citys. I dont think they were supposed to start with the nukes ,but it was the final ace card that would absolutely mission kill the enemy if nothing else, if its anywhere in range.

Declan

[butler1850]

@AK84

Did’nt British Ships carry an atomic depth charge in the cold war? How the hell are you supposed to survive that yourself nev er mind the sub?

Well, it’d be a fairly small nuke, and exploding at some depth under water. I’d think that the time from drop, through sinking to depth, would allow sufficient time for the plane to escape the blast danger radius. The proviso, of course, would be that the aircraft was hardened against any EMP that may be released, and extend above the water (does an underwater nuclear explosion create an EMP above the surface of the water for any significant distance?).

The planes that dropped on Hiroshima, and Nagasaki escaped fairly well, and those aircraft were certainly not built to the standards of modern aircraft.