Submarines Noise levels

Diesel Submarine Radiated Noise Trend

Actually I have a bit of trouble believing that chart Austin, first of all those American stars are nukes and not diesel electrics.

Second is it showing diesels operating with diesel engines running or on electric drive... quite different things BTW.

When running off batteries most diesel electrics would compare quite favourably to most nukes as there are no noisy gears or reactor cooling pumps operating.

Equally even a noisy sub can be operated near a choke point in a lie and wait tactic where it can remain noiseless and motionless waiting and listening for targets to come past it.

^^ Garry , Dont take that chart as a gospel truth but a trend in conventional submarine.

Its true that Nuclear Submarine have lot of pumps ,reactor running which would make them noisy , compared to conventional subs running on battery.

But Nuclear submarine have far more comprehensive silencing measures implemented in them , the much bigger size and unlimited power allows them to do so . While Diesel Electric Submarine have their limitation on size and power hence they are limited to what can be implemented to reduce acoustic field.

There is some thing called Full Silence regime on Nuclear Submarine where it moves at slow speed ,all non essential stuff including pumps are shutoff , moments are restricted ( even no toilets ) , so Nuclear sub can remain and be more silent then diesel subs.

Choke point business are best done by Conventional Subs , they are small in size ,choke point depth ( generally not greater then 200 m ) allows them to lie low and run on battery for long without the need to recharge for long time and AIP makes it much longer.

Its always good to have a mix of Nuclear and Conventional subs as they have their own task cut out and are good at specific task , In US there are lobbies that think opting for Conventional Subs will eventually kill Nuclear submarine and their associated industry

Thankfully Russia did a right thing of having mix of both , its a cost effective option as well.

My main problem with the chart is that it doesn't actually list the scale of noise, it just says it is in decibels.
As such the scattering of subs on the chart mean little except the downward slope suggests they are all getting quieter... which is a given anyway.

Its true that Nuclear Submarine have lot of pumps ,reactor running which would make them noisy , compared to conventional subs running on battery.

There are reactors that use natural circulation for cooling, but at the end of the day lots of noises on subs like opening torpedo doors, pumping water into and out of ballast tanks for trim, propeller noise, mechanical noise is going to be less on an electric than on any other type. Non nukes have their advantages especially in shallow waters because of their smaller size and manoeuvre capability and of course cost, but their fundamental advantage is in their reduced noise signature because electric motors make very little noise even at full power.

But Nuclear submarine have far more comprehensive silencing measures implemented in them , the much bigger size and unlimited power allows them to do so .

If that were true then the US could simply test its anti sub capability against its own nuclear power subs instead of inviting European and Australian conventional subs to exercise with them so they can practise operating against conventional subs.
It seems these tests were useful and the USN has invited a European country to keep sending its subs for exercises.
What would be the point if diesel electrics were noisier than nukes?

There is some thing called Full Silence regime on Nuclear Submarine where it moves at slow speed ,all non essential stuff including pumps are shutoff , moments are restricted ( even no toilets ) , so Nuclear sub can remain and be more silent then diesel subs.

Yes, I know about running silent on a sub, but even running on silent in a nuke and a diesel electric are not the same thing... in a nuke you keep the reactor running which means noise. In a diesel electric that means running on electric which is much quieter clearly... even in a natural circulation reactor there is the noise of fluids moving that doesn't sound like other things in the ocean.

In US there are lobbies that think opting for Conventional Subs will eventually kill Nuclear submarine and their associated industry

There are lobbies in the US that think universal healthcare is communism too.

A kilo could probably operate for 4-5 days on batteries before having to recharge... that is plenty of time to sit and wait for the right target or lay mines and sneak away to recharge.

GarryB wrote:My main problem with the chart is that it doesn't actually list the scale of noise, it just says it is in decibels.
As such the scattering of subs on the chart mean little except the downward slope suggests they are all getting quieter... which is a given anyway.

These are just trends and not a ballpark figure ,even if scale were to be provided it would be little value.

I find it hard to believe to believe that Australian Collins are being rated in noise equal to advanced Kilo when they were mentioned as Rock Band under water by Western media and German U-212 being rated lower then adv Kilo when it should be on par or better.

There are reactors that use natural circulation for cooling, but at the end of the day lots of noises on subs like opening torpedo doors, pumping water into and out of ballast tanks for trim, propeller noise, mechanical noise is going to be less on an electric than on any other type. Non nukes have their advantages especially in shallow waters because of their smaller size and manoeuvre capability and of course cost, but their fundamental advantage is in their reduced noise signature because electric motors make very little noise even at full power.

Yes I am aware of the use of natural circulation at slow speed but those noises from ballast , motors , trip etc affect conventional and nuclear subs and a nuclear subs have much bigger sonars and other sensors to catch up such noises compared to conventional subs.

Conventional subs are good for choke and intelligence gathering operations.

If that were true then the US could simply test its anti sub capability against its own nuclear power subs instead of inviting European and Australian conventional subs to exercise with them so they can practise operating against conventional subs.
It seems these tests were useful and the USN has invited a European country to keep sending its subs for exercises.

They do lot of test viz a viz conventional subs against Australian or European countries , these are tactics , weapons ,how to play ball in shallow waters and even open seas , lot of stuff besides noise , A sub is more then just noise.

What would be the point if diesel electrics were noisier than nukes?

because its cheaper to build and operate ,very few countries can build and operate quality nuke subs and with AIP the conventional subs are getting better and as I said submarine is more then noise , Tactics , Weapons ,Training and Doctrine play an equal role.

Yes, I know about running silent on a sub, but even running on silent in a nuke and a diesel electric are not the same thing... in a nuke you keep the reactor running which means noise. In a diesel electric that means running on electric which is much quieter clearly... even in a natural circulation reactor there is the noise of fluids moving that doesn't sound like other things in the ocean.

Nuke Subs do have battery on them to provide powers and they have small creeper propellers one can see in Akula that gives them slow speed.

All things being equal which I have mentioned above a 4th gen Conventional Sub like Lada will have its own advantage over 4th gen Yasen in shallow water operation.

So conventional subs do have an edge in specific roles.

There are lobbies in the US that think universal healthcare is communism too.

I think that was also a reason Democrat got defeated in recent Senate elections , health care is good as long as it can profit the big companies out there.

A kilo could probably operate for 4-5 days on batteries before having to recharge... that is plenty of time to sit and wait for the right target or lay mines and sneak away to recharge.

The Kilos are quite potent subs and can do many different task and these days they even come with Klub.

http://manglermuldoon.blogspot.in/2013/12/chinas-anti-access-strategy-submarine.html

To provide a point of reference, the following acoustic signatures are from "Chinese Evaluations of the U.S. Navy Submarine Force" and "CHINA’S FUTURE NUCLEAR SUBMARINE FORCE"

Ocean background noise - 90 decibels
Seawolf-class - 95 decibels
Virginia-class - 95 decibels
636 Kilo class - 105 decibels
Akula-class - 110 decibels
Type 093 - 110 decibels
Type 094 - 120 decibels

Austin wrote:http://manglermuldoon.blogspot.in/2013/12/chinas-anti-access-strategy-submarine.html

To provide a point of reference, the following acoustic signatures are from "Chinese Evaluations of the U.S. Navy Submarine Force" and "CHINA’S FUTURE NUCLEAR SUBMARINE FORCE"

Ocean background noise - 90 decibels
Seawolf-class - 95 decibels
Virginia-class - 95 decibels
636 Kilo class - 105 decibels
Akula-class - 110 decibels
Type 093 - 110 decibels
Type 094 - 120 decibels

Could be interesting to know the speed/deep and propulsion mode (diesel or electrics) for these numbers.

Austin wrote:http://manglermuldoon.blogspot.in/2013/12/chinas-anti-access-strategy-submarine.html

To provide a point of reference, the following acoustic signatures are from "Chinese Evaluations of the U.S. Navy Submarine Force" and "CHINA’S FUTURE NUCLEAR SUBMARINE FORCE"

Ocean background noise - 90 decibels
Seawolf-class - 95 decibels
Virginia-class - 95 decibels
636 Kilo class - 105 decibels
Akula-class - 110 decibels
Type 093 - 110 decibels
Type 094 - 120 decibels

interesting how Chinese measured Seawolf/Virginia noise? no source provided or I am missing omething? all other sources are either US intel or authors nothing from China or Russia. Funny is that 677 is noisier than 636.6 built for China accorduing tho those sources

Which Akula they're talking about ? Because Los Angeles class SSN faces difficulties in finding 971-Akula SSN ( 90 db )

I think thats the only time I've seen actual numbers instead of scale-free graphs

I wonder which 636 they are supposed to be & how much difference there is between the versions?

Austin wrote:http://manglermuldoon.blogspot.in/2013/12/chinas-anti-access-strategy-submarine.html

To provide a point of reference, the following acoustic signatures are from "Chinese Evaluations of the U.S. Navy Submarine Force" and "CHINA’S FUTURE NUCLEAR SUBMARINE FORCE"

Ocean background noise - 90 decibels
Seawolf-class - 95 decibels
Virginia-class - 95 decibels
636 Kilo class - 105 decibels
Akula-class - 110 decibels
Type 093 - 110 decibels
Type 094 - 120 decibels

Nicely rounded numbers.
Submarine noise levels are closely guarded secrets by the military.
These figures have zero credibility. At least they should have not rounded numbers. Hey, if they had put decimals, it would have looked more credible.


Fools.

GunshipDemocracy wrote:

Austin wrote:http://manglermuldoon.blogspot.in/2013/12/chinas-anti-access-strategy-submarine.html

To provide a point of reference, the following acoustic signatures are from "Chinese Evaluations of the U.S. Navy Submarine Force" and "CHINA’S FUTURE NUCLEAR SUBMARINE FORCE"

Ocean background noise - 90 decibels
Seawolf-class - 95 decibels
Virginia-class - 95 decibels
636 Kilo class - 105 decibels
Akula-class - 110 decibels
Type 093 - 110 decibels
Type 094 - 120 decibels

interesting how Chinese measured Seawolf/Virginia noise? no source provided or I am missing omething? all other sources are either US intel or authors nothing from China or Russia. Funny is that 677 is noisier than 636.6 built for China accorduing tho those sources

It is more than that.

An electric submarine must generate less noise than a nuclear in electric mode.
It hasn't got cooling pumps, boiling water in the reactor and control roads in it.

Additionaly the cruisinf speed of the nuclear submarine higher than for the diesel/electric, means more noise at the same speed.


If the diesel works in diesel mode then OK, it is noisy ,but not in electric mode.

971 is Akula only ( talking about nato naming . )

Austin wrote:http://manglermuldoon.blogspot.in/2013/12/chinas-anti-access-strategy-submarine.html

To provide a point of reference, the following acoustic signatures are from "Chinese Evaluations of the U.S. Navy Submarine Force" and "CHINA’S FUTURE NUCLEAR SUBMARINE FORCE"

Ocean background noise - 90 decibels
Seawolf-class - 95 decibels
Virginia-class - 95 decibels
636 Kilo class - 105 decibels
Akula-class - 110 decibels
Type 093 - 110 decibels
Type 094 - 120 decibels

To be fair the 110 is for the old Akula's.

The modernized ones are supposed to be quieter by how much well remains to be seen

If you guys are more into more scientific aspect (with resources) You guys should look at E.Miasnikov's work :

Generic issue:
https://www.armscontrol.ru/subs/snf/snf0322.htm

Specific on Submarine :
https://www.armscontrol.ru/subs/snf/snf03221.htm

Another of his work :
http://members.chello.pl/m.ostrowski7/files/Miasnikov%20-%20The%20Fundamental%20Limits%20of%20Passive%20Acoustics.pdf

Another wonderful book on the subject. Written by American Author Tom Stefanick. It is also and still the unclassified model of Submarine Source Level.

Strategic Antisubmarine Warfare & Naval Strategy
https://www.scribd.com/document/380271381/Strategic-Antisubmarine-Warfare-Naval-Strategy

It is easier and cheaper to sink an  aircraft carrier . Than to allow  it's planes to fly around . Submarines can keep an aircraft carrier at a distance .  But why do submarines still fire torpedo ?  This in my view  has disadvantages . Even if submarine is undetected , and fires torpedo . Then noise from torpedo , will identify the position of submarine . Range of torpedo is relatively small . Allowing a small search area to be set up , by anti-submarine  forces .

Why not use torpedo tube  to launch anti-ship cruise  missiles . They can be launched from much greater distance . Second the launch is less noisy and less likely to give position of sub away . And even if launch position becomes known , the search radius is greater . Allowing sub more time to escape  . And finally  the cruise missile is faster and  more difficult to intercept  than torpedo .

Locating a surface fleet , can be done by sub itself . Even if ships have engines shut down . And acoustic long range detection is not possible . Drones can be launched by sub . To search surface  . Sending real time info back to sub . Once ship located , then missiles launched . Flight time to target relatively short , allowing cruise missile to do a search pattern near target , before it escapes .

nomadski wrote:It is easier and cheaper to sink an  aircraft carrier . Than to allow  it's planes to fly around . Submarines can keep an aircraft carrier at a distance .  But why do submarines still fire torpedo ?  This in my view  has disadvantages . Even if submarine is undetected , and fires torpedo . Then noise from torpedo , will identify the position of submarine . Range of torpedo is relatively small . Allowing a small search area to be set up , by anti-submarine  forces .

Why not use torpedo tube  to launch anti-ship cruise  missiles . They can be launched from much greater distance . Second the launch is less noisy and less likely to give position of sub away . And even if launch position becomes known , the search radius is greater . Allowing sub more time to escape  . And finally  the cruise missile is faster and  more difficult to intercept  than torpedo .

Locating a surface fleet , can be done by sub itself . Even if ships have engines shut down . And acoustic long range detection is not possible . Drones can be launched by sub . To search surface  . Sending real time info back to sub . Once ship located , then missiles launched . Flight time to target relatively short , allowing cruise missile to do a search pattern near target , before it escapes .

Torpedoes are needed against other submarines imo than against surface ships.

Torpedoes can't be shot down by air defence systems... and in terms of sinking even very large ships they are the best solution.

For use against ships the torpedo is designed to go under the ship and detonate... generating an enormous bubble of gas... which of course rises up and lifts the ship out of the water. But look at any ship in a dry dock... if you only supported their weight in one position or lifted them with one crane then they would break in half at the point of lift.

That is what happens when the bubble of gas lifts the ship... it breaks the back and when split in half no ship would remain on the surface.

There is a saying that torpedoes let water into the hull of a ship while anti ship missiles let in air in the top.

Not strictly accurate, because AShMs let fire into the ship which can be worse than letting in water...

And some torpedoes have ranges of 50km+.

For areas where enemy ships have to pass you could also lay mines too.

For use against enemy subs the Russians have developed versions of the Club missile that is a Mach 2 or Mach 2.5 ballistic rocket that flies a simple path to where the enemy sub is located to drop a torpedo into the water to then engage the sub. The rocket is faster than anything moving through water and much quieter, and when used against subs there is no air defence system to worry about.

Against a ship it would be much less effective.

There is no reason why a torpedo could not initially operate at a fairly low speed limiting the noise it generates to begin with and then accelerate as it gets closer to the target.

I think the main point is that if you detect an incoming torpedo from 20km range you wont be manouvering to launch an anti sub weapon to engage the sub, you will be manouvering your ship to make yourself the smallest possible target and to leave the danger zone while you work out if it is heading towards you or one of the other ships you are with...

If it was an anti ship missile then you would activate all your radar and SAMs and CIWS and prepare to launch decoys and jammers etc etc to defend the ship and pass on information to other ships nearby to do the same.

There is rather less they can do in the case of an incoming torpedo to be honest...

Good of the Russians to think about this . So it looks like the fastest means of delivery is a rocket . The best type of warhead is a  underwater  type . And best detection depends on resources  . Sattelites launched in LEO for this particular case , may provide best and most updated info on location of fleet . If not available  , then long range over horizon radar . If not then long range sonar . If not then long range surveillance  drone .

But I thought , probably the cheapest system , is one that does everything itself . A low RCS , high altitude and long range drone / missile / torpedo  , can fly without GPS , detect without radar or sonar . On locating target , it can shed engine and wings , then fire rocket . Approach fast . Near target dive into water.  And activate below water mark . No need for sattelite , anti- sattelite , ship , sub , radar , sonar ......... like flying fish .