Bring the Heat Looks at Depth Charges

The post begins;

You’ve seen enough movies to have a basic grasp of what a depth charge is. A cylindrical container full of explosives rolled off the back of an escort ship that detonates when it reaches a preset depth, as determined by a hydrostatic firing device (know in the business as a “firing pistol” for some reason).

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Part II

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Think Defence hopes to start sensible conversations about UK defence issues, no agenda or no campaign but there might be one or two posts on containers, bridges and mexeflotes!

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Mike W
January 18, 2014 3:20 pm

Can anyone explain to me why the humble depth charge is no longer used on board ships. I believe the old Nimrod used to carry some in its MPA role. However, none have been carried by the surface fleet for some time now. Surely they would be useful as a supplement to ASW torpedoes.

January 18, 2014 3:57 pm

MikeW – I guess its all to do with kill probabilities – a self-guided munition (active torpedo) will have a high probability of finding the target, where depth charges are wet-finger-in-the-wind weapon of chance. For the same level of certainty of disabling opposition boats it might take a dozen or more DC to equal the effect of one homing torpedo. Depending on the size of bang in the DC of course.

I read a while back that some of the more modern ‘mines’ are not big explode-on-contact balls on chains, but are more like tethered torpedo tubes with a passive (sonar or MAD) sensor perched on top – when the launcher thinks its detected a target the torpedo is fired. It seems the modern way is to use self-guided anti-submarine weapons wherever possible.

January 18, 2014 3:58 pm

I would imagine that the first consideration is that the chances of running a ship over a sub these days without receiving several torpedoes can be averaged to about 0%, with the odds of a protracted depth charge engagement ending up sinking the sub being about 5%, which is significantly worse than any torpedo (even tigerfish!) and a torpedo also has the advantages of having at least some stand off range.

Planes don’t need to worry about being torpedoed, and you can’t drop a torpedo on something in shallow water from aircraft because said torpedo is unlikely to have time to manoeuvre to avoid hitting the bottom. Therefore, depth charges on aircraft are a reasonable proposition given that if the water is to shallow for a torp then simply dividing the depth of the water by 2 and setting the fuse for that gives you quite a respectable chance of detonating close enough to do some damage if you drop it over the top of the sub.

Hence why flying things have depth charges and floaty things don’t.

Mike W
January 18, 2014 4:54 pm

@Chris and Peter

Thanks to both of you for replying. Between you you appear to have covered every conceivable reason why ships do not have them and planes do.

It was just that I thought they might still provide a useful weapon system in the case of a really sudden attack when the vessel’s Lynx or whatever might not be airborne.

From a real landlubber!

John Hartley
January 18, 2014 6:02 pm

A semi modern use for (small) depth charges from boats was championed by the Swedes. When Soviet subs strayed into Swedish waters, they did not want to sink it & start war with Russia. So they used small depth charges to explode near, but not too near, in order to drive the sub out of their waters.

January 18, 2014 6:33 pm

We do not have depth charges on inventory but BAE make the mark 11.
BAE also make stonefish mine which could also be useful.
We really have gave away a lot of capability.
But in the event of them being needed BAE make them for other people so we can just put in an order.
What is the minimum depth in which a stingray torpedo can be used in?
Can a depth charge can be used in shallower water?

January 18, 2014 7:18 pm

Mike W, instead of depth charges, surface ships carry lightweight homing torpedoes, in small tubes (in the US Navy’s case, the Mk32 triple tube mount, one on each side). This installation is actually smaller than a typical depth charge rack would be. And because it can be mounted along the sides, it preserves valuable space along the centerline and on the fantail.

Still, the surface launched ASW torpedo launcher is considered something of a last ditch weapon, since by the time you’re in shooting range, you’ve been inside the sub’s shooting range for a while.

January 18, 2014 7:40 pm

This rule does not apply to the Russians, who tend to bolt any number of just in case weapons onto their ships. So you will still see rocket propelled depth charges on Russian ships.

Mike W
January 18, 2014 9:47 pm


Thanks very much for your answer about the surface launched ASW torpedo launcher. Very informative.

The other comments are intriguing too. I thought I did read something somewhere recently about the British ordering some depth charges once again but my memory is fallible and I can’t even remember for which platforms they were intended. I don’t think I imagined the whole thing!

January 18, 2014 10:20 pm

Think the Russian systems were called RBUs and the latest variants have guided rocket depth charges. In the end, it’s about similar to light weight torpedos in effect and deployment, just that one has a longer time in flight while the other hits the water faster.

January 18, 2014 11:55 pm

Pretty sure the Lynx and also the Merlin can carry depth charges:

Good to see the RN manages to keep it”s website up to date, they still have Type 42’s and 22’s, so perhaps things aren’t as bad as we thought afterall!!

January 19, 2014 12:53 am

Part II, with a nod to you British types, will be up tomorrow.

January 19, 2014 4:28 am

Mk 11 DC still in RN service and a valid weapon. The Yanks are kicking themselves for eliminating them from their inventory.

January 19, 2014 6:02 am

Part of this is because surface ship have gone from active sensors to passive. Depth Charges create a lot of noise along with a low probability of Kill, making it very difficult to relocate the sub.

The US Mk 54 torpedo is designed to operate in shallow waster.

The Russian RBUs are not just ASW weapons, they are also counter torpedo weapons.

January 19, 2014 7:19 am

I’m sure DC have their uses but I’m guessing there are probably two reasons why they became rare.
1. Modern torpedo manufacturers claim that the weapons can work in similar conditions (i.e shallow water). Eurotorp’s MU90 website says less than 25 m. I doubt they are the only manufacturer making these claims and, who knows, it might be true. The threat in the Gulf region is hardly lost on capability planners.
2. If I read an earlier TD article correctly, the mk 11 has about 80 kg of explosives compared to 90 kg on a 500 lb bomb. Well, with a decent delay on any of the usual family of dumb bombs, you have a serviceable depth charge (in shallow water). Now it could be different families of explosives I’m comparing here, but I don’t think that the results will be too wildly disproportionate. We are talking about very shallow water, after all. Of course, you have to know that you want such a bomb fuse to be available and you have to have a suitable platform – which is where your DC comes to the fore. Nevertheless, with the right preparation, a response to a really shallow water problem is available.

John Hartley
January 19, 2014 10:42 am

A torpedo is good if you want to kill a submarine, but a depth charge is better, if you just want to chase it away. Captain Sensible “Glad its all over” for the Russian submarine grounded incident. “The red red (something) will pay the price, for giving to the people who never ever go to war”.

January 19, 2014 11:50 am

Observer. Yes the Russians rocket assisted depth charges are the RBU 6000 and 1000, the latest iteration is guided. But most of their ships and kit are still 1980s vintage and so are unguided DCs. Also the Grisha class patrol boats do have good old fashioned DC launchers with DCs to drop of the back. They are a great example of the bolt everything onto a platform that was the standard soviet way.

January 19, 2014 1:48 pm

Considering the role of the old Grisha class fitting depth charges makes plenty of sense. They were intended for coastal patrol or operations into inland seas like the Baltic Sea. Close to shore in the shallows a Submarine doesn’t have the ability to manoeuvre or go deep like in the open ocean. The Grisha class was fitted with a medium to high frequency dipping sonar similar to that fitted to an ASW helicopter. In confined waters using their dipping sonar they can get over a submarine and drop a depth charge on it. They were even operated by the KGB up into the 1980’s.

The type gets a mention in Tom Clancy’s Red Storm Rising (that is the book with a good ghost writer).

January 19, 2014 5:34 pm

Would it be possible to use depth charges on ships as an anti-torpedo defence? Using an array described above, only a rough direction would be needed. Is the pressure wave in the water enough to damage the torpedo or it’s sensors? It’s seems like they should be, but it’s such a simple idea I’m sure that it’s been though of before and that there’s a good reason why it won’t work…

January 20, 2014 10:25 am

Modern torpedo manufacturers claim that the weapons can work in similar conditions (i.e shallow water). Eurotorp’s MU90 website says less than 25 m.

If it’s much less than that, you will be able to see bits of the sub poking out above the water. Unless (as M&S will soon be along to confirm) the Chinese and the Iranians are building a revolutionary new type of Very Flat Submarine, 80 m long and 25 metres beam, but only five feet high.

January 21, 2014 10:33 am

Here is a picture (scroll down a bit) of HMS Monrose (a RN T23) firing a Stingray torpedo. One of those, closing down your bearing would ruin you day, more than any DC!

PS – Would like to see similar fitted to the T45s. As we have so few of them, they need all the self defence possible!

January 21, 2014 10:53 am

EastAnglian – ref Stingray launch – apparently the tubes (two each side to the forward end of the hangar structure) spit the torpedo across the deck at chest height. A bit of a shock to passing personnel… It seems strange the RN painted bright yellow ‘Don’t Stand Here’ markings on the deck but only to give the covers room to open without hitting people or stuff, where according to the deck markings you can stand in front of the emerging weapon in a one-sided game of chicken if you like? “I got it.. I got it..” Duff! Splash! “I don’t got it..”

January 21, 2014 11:38 am

@Chris – Genuine LOL!

Imagine the fun! Some comedy genius was behind the design of this, mark my words…

John Hartley
January 21, 2014 6:56 pm

I realise I am talking to myself over depth charges to scare off submarines, but I wonder if the Royal Ordnance 120 mm mortar turret could be adapted for naval use? Developed for armoured vehicles circa 1985. Could launch mortar bombs 8.5KM or rocket assisted 12KM. An inshore patrol vessel could provide fire support to land forces & if a 120 mm depth charge was developed, also provide the means to drive off unidentified submarines.

January 21, 2014 7:39 pm

@John Hartley
Nice idea, if you used the AMOS system you get two barrels and an auto-loader and it has also been tested on the Combat Boat 2010 so has had maritime testing.

January 24, 2014 10:36 am


“Hence why flying things have depth charges and floaty things don’t.”

Top notch…a brilliant technical description that even some in the Press might be able to understand….presuming of course that the most erudite members of the Fourth Estate are at least sober and not doing stories about models in their underwear, umm, entertaining footballers and such like…..