Anti-submarine warfare

[viper37]

If there was a war between major powers today, or even against a smaller nation using submarines, is there any kind of static/semi-static protection a naval base can use against ennemy submarines?  I mean to exclude active attack submarine patrols from the equation.  Aside from that, anything to prevent an ennemy sub closing in and lauching a bunch of torpedos to sink a bunch of ships in the harbour?

[Viking]

I presume most modern military ports have modern versions of the WWII magnetic indicator loops, the same technology which is used to help traffic lights improve traffic flow by identifying traffic loads.

[Razgovory]

They had underwater listening buoys from Greenland to Great Britain during the cold war.  I imagine they have something similar today around military bases.

[CountDeMoney]

If there was a war between major powers today, or even against a smaller nation using submarines, is there any kind of static/semi-static protection a naval base can use against ennemy submarines?  I mean to exclude active attack submarine patrols from the equation.  Aside from that, anything to prevent an ennemy sub closing in and lauching a bunch of torpedos to sink a bunch of ships in the harbour?

Yes.

[Viking]

They had underwater listening buoys from Greenland to Great Britain during the cold war.  I imagine they have something similar today around military bases.

http://en.wikipedia.org/wiki/SOSUS

SOSUS is now declassified. A replacement system almost certainly is in operation. The Radio Directionfinding antennas they set up at Grindavík and Höfn at still in place and while not actively operational they are routinely maintained and the US has "janitorial staff" on both locations. SOSUS certainly is restartable and while the capability is now "mobile" the modern system is certainly on and active in the north atlantic all the time.

[The Brain]

You're still fucked if the enemy plays the Prien card as an event.

[grumbler]

If there was a war between major powers today, or even against a smaller nation using submarines, is there any kind of static/semi-static protection a naval base can use against ennemy submarines?  I mean to exclude active attack submarine patrols from the equation.  Aside from that, anything to prevent an ennemy sub closing in and lauching a bunch of torpedos to sink a bunch of ships in the harbour?

I'm not sure what you are asking.  There are few harbors (none I can think of offhand) which would allow a submarine to simply fire into it and hit ships.  Harbors exist where there are sheltering landmasses to keep wind and weather from moving around the ships at dock.  Those same landmasses would shelter a ship from torpedoes, as well.  The4 sub would have to enter the harbor to attack the ships there.

Generally, harbors have a very restricted shipping channel, which the sub would have to use, submerged, to gain access.  Simple navigation requirements would force it to use its periscope pretty much constantly to stay in the channel, which means it would be highly vulnerable to detection.  Visually, if by no other means.

That's why nations used midget subs for harbor penetration in WW2, and even then had them follow ships into the harbor in preference to independent penetrations.  My info is out of date these days, but the Norwegians and Germans used to be the best at that kind of thing.  Maybe North Korea could do it, as well, but I have always been skeptical of regimes like North Korea that reward fantasy over reality.

Against the midget threat, there is no active defense system of which I am aware, but the threat isn't significant enough to devote a lot of time to.  Midget sub ops require lots of planning, and the targets are too mobile to be predictable enough for that planning to be highly useful.  The midget sub operator has to count on being lucky enough that the target is still there.

[CountDeMoney]

Against the midget threat, there is no active defense system of which I am aware, but the threat isn't significant enough to devote a lot of time to.  Midget sub ops require lots of planning, and the targets are too mobile to be predictable enough for that planning to be highly useful.  The midget sub operator has to count on being lucky enough that the target is still there.

There are a number of sonar-based perimeter intrusion detection systems deployed at select locations for various, high-profile clientele designed specifically to counter the midget little people sub and frogman frogperson threat. 

[Razgovory]

I think Viper is talking about a Royal Oak type incident.

[grumbler]

There are a number of sonar-based perimeter intrusion detection systems deployed at select locations for various, high-profile clientele designed specifically to counter the midget little people sub and frogman frogperson threat. 

Those are point-defense systems.  They wouldn't stop a torpedo-firing miniature sub, nor would they protect a harbor. 

[viper37]

I'm not sure what you are asking. 

I assume that, in times of war, there would be regular patrols along harbors, by subs and surface ships to detect ennemy submarine, way before they enter range to cause any damage.

But assuming an ennemy sub can get pass these patrols, avoid detection entirely and get very close to the port, what could prevent an attack?  It could take some time for the navy to react, to send helos/airplanes to track the sub, so I'm guessing an attack such as the one on Scapa Flow in WWII could theoritically be possible.

So I'm asking what can be done today to prevent this kind of attack, aside regular patrols by aircrafts, submarines or surface vessels, if all these fails, do harbors have some kind of net (physical or theoritical with sensors) to prevent/detect a sub getting way to close to the port and ideally, hinder his movement sufficiently so the navy (British or American, say) would have time to find it and sink it.

[The Brain]

Sweden experimented with the Mark I rock. It successfully caught a Russian sub right outside a Swedish naval base in 1981.

[grumbler]

I assume that, in times of war, there would be regular patrols along harbors, by subs and surface ships to detect ennemy submarine, way before they enter range to cause any damage.

You wouldn't use a sub for this type of patrol.  The water is much too shallow, and passive detection ranges too short.  One uses subs offensively, in general.

I suppose that some nations would attempt to patrol off their ports with a small craft, but this wouldn't be much use except for visual detection.  The bigger threat is submarine mining; there, just about everyone has some coastal mine countermeasures ships and plans to create swept channels.

There is also defensive mining.  I know that the US had plans for defensively mining at least some harbors some decades ago, but don't know if those are still in effect.  I'd suspect not, since the subs small enough to approach ports have been replaced by larger, more capable ones.

But assuming an ennemy sub can get pass these patrols, avoid detection entirely and get very close to the port, what could prevent an attack?  It could take some time for the navy to react, to send helos/airplanes to track the sub, so I'm guessing an attack such as the one on Scapa Flow in WWII could theoritically be possible.

the Scapa Flow attack was a one-of-a-kind attack, against a "harbor" that was unprepared and wasn't really a harbor at all.  It was an anchorage.  The RN moved in before finishing its defenses.   Unlike your typical port, there were no channels into Scapa; it was open to the sea except where blockships eliminated certain approaches (and the others had antisubmarine nets, which I don't think anyone uses any more).

So I'm asking what can be done today to prevent this kind of attack, aside regular patrols by aircrafts, submarines or surface vessels, if all these fails, do harbors have some kind of net (physical or theoritical with sensors) to prevent/detect a sub getting way to close to the port and ideally, hinder his movement sufficiently so the navy (British or American, say) would have time to find it and sink it.

Most subs are far too large to carry out this kind of operation.  Midget subs could do it, but I don't know of anyone who is deploying that type of midget sub (one with torpedoes, as opposed to the commando-type midget sub).

[Capetan Mihali]

Sweden experimented with the Mark I rock. It successfully caught a Russian sub right outside a Swedish naval base in 1981.

[Siege]

I thought modern subs fire harpoons and cruise missiles, thus not needing to get into port.