Technical question - reverse depth charges

[Safe-Keeper]

So something I've been wondering is - why didn't, and don't, the subs do the same thing, only in reverse? When you hear the destroyer coming, release depth charges filled with explosives. These reverse depth charges would be light enough to rise rapidly and explode once near or at the surface, deterring, damaging or even sinking the DD. Sounds to me like a great anti-anti-ASW measure. In fact, it sound to me like they'd be ten times as effective as depth charges, as DDs often had to make educated guesses as to where the sub was, while the sub knows that once it's detected, the DD will past right overhead.

So given that it would probably work so well if it worked, and that it's such a simple concept, there has to be a good reason why "reverse depth charges", or "surface charges", aren't in widespread use. Anyone care to educate me?

[Kapitan]

Think about the force it explodes with its enough to sink a submarine so sure it would be sink a DD but if your talking WW2 era submarines then they cant dive as deep as a modern but so they release that charge the concussion could sink them too or the DD could break apart sink rapidly and take the submarine down with them too.

failing that say your caught on the surface by an aircraft it drops a depth charge on you the concussion could set off the charges on the deck, unless you plan to make them releaseable like mine layers.

ever wondered why diesel boats tend to be smaller than nuclear boats? and its not always down to reactors and gubbins inside its because if you pile on the wieght you got to put a dozen more batterys inside the thing, i went onboard an oberon a while back each battery wieght 3/4 of a tonne and gives out 2 volts DC and the entire lower deck is filled with them and that propells that type of submarine at around 15 knots submerged best outta world war two boat was what 9knots

its not crazy could be plausable but its risky and today we have wire guided torps and we can hear the boat before it hears us.

[GoldenRivet]

1. Such a device would only be effective at a relatively shallow depth (30m or less) BECAUSE... the "reverse depth" charges would have to be stored in some sort of vertical launch tube. once the tube was opened the tube would have to be strong enough to withstand massive sea water pressure if these things were to be launched any deeper than 30 meters.

2. you could side step this issue by storing the "surface charges" externally to have them mechanically released at greater than 30 meters depth... however the thought of having depth charges fall down on me... or aircraft shooting at me while having massive explosive charges stored externally is not a happy thought at all. the risk of these things spontaneously exploding due to sea corrosion... or due to attacks against the boat far outweigh the benefit of having them on board IMHO

3. Since these surface charges would not be aimed, they would probably be released in some quantity in order to increase the chance of scoring a hit... even if you did score a hit on one destroyer... the remaining destroyers which might not be aware of the subs exact position - are now more than abundantly aware of the subs position because of the floating surface charges bursting to the surface. - akin to ringing the DD Dinner bell

4. the risk of explosion during the ascent of the surface charges. what happens when you launch a salvo of these surface charges - which are much more highly explosive than depth charges - and on the way up they have a rather intimate encounter with a DDs depth charges? the massive series of explosions which would result might just be enough to critically damage the sub.

5. Finally, the only indication that the DD is directly overhead would be the sound of the splashes. even if you timed it perfectly and released your surface charges right at the exact moment you heard the DDs splashes... it would take several seconds... perhaps 10 - 15 seconds for the surface charges to reach the surface.... in this 10 - 15 seconds, the DD traveling at a good 30 knots would have covered a distance of about 700 - 800 feet. The odds of your reverse depth charges finding their mark are signifigantly slim to say the least.

In the end the surface charges would prove to be an increadibly innefective weapon which serves little more purpose than to expose the exact position of the relatively slow moving u-boat

I had a similar type of idea of using some kind of floating and possibly magnetic mines against destroyers etc. They might have a delayed charge that would detonate once they become attached to a surface vessel. It's a pretty tricky situation when being chased by a destroyer, it would require some kind of simple and effective counter measure from the sub.

[CaptainHaplo]

The other issue is that DC's make use of the fact that an explosion underwater is subject to specific physical properties. A surface (or near surface) explosion is under a highly different set of physics. The amount of explosive needed per charge to be effective would have been MUCH higher than that needed by a normal DC.

Also remember that a submarine hull is under vastly more amounts of stress per square inch than the hull of a floating ship. This also contributed greatly to the lethality of DC's - which again would change the equation when used against a surface ship.

If anything, I am suprised countermeasures such as tangle wires (for DD props were not used. Dive and as you do, release a semi-bouyant net to tangle the attackers props. You know he is going to be coming.... Put it into his path, immobilize him (or at least seriously harm his mobilty) - then turn the tables and blast him.

[Platapus]

Ok, so it seems like using "reverse depth charges" is not a good way to destroy a destroyer.

But how about a weapon system that would deliver a long series of smaller underwater explosions over a wider area to help the submarine hide/escape?

Even a small explosion adversely affects sonic and ultrasonic sonar.

A good sub Captain can do a lot if he has 5 minutes of the enemy being deaf.

[GoldenRivet]

i like it.

sort of an underwater cluster bomb of low yield explosives intended to destroy the acoustic properties of the area.

i think such a device would have to be made into the form of a slow moving torpedo which creates bubbles of cavitation.

the torpedoes could be fired into several directions - each one emitting sub like sound effects and large bubbles.

this would force the destroyers to attack each individual sub before possibly finding the real sub.