Why not just make an undwerwater sonar array and drop torpedos anywhere from helicopters...

The thing is that incoming ships will see the helicopters on their radar. Also helicopters are limited to smaller short range torpedoes (MK50) for example. I'm thinking long range big warhead torpedoes that can take out a cruiser size ship. Put a 6 pack in a concrete container (the tubes being waterproof) and put them in water over 300 feet deep, so they won't get detected. The cost would be resonable I would think. I agree about the seabed array. But if you mix that with surface radar from a landbase, you'll have the bad guys sinking fast.

Although this article suggests it was withdrawn by 2002, the US CAPTOR mine was exactly that: an encapsulated torpedo (primarily ASW) that could be laid by various platforms. http://www.exwar.org/Htm/ConceptDocs/Navy_USMC/MWP4thEd/appendix_e.htm As to whether the mobile mines are pretty much a torpedo also, could be argued, as they may or may not actively/passively chase down a target after being laid. The only serious issues here could be: is the weapon adequately protected against tampering (by underwater teams trying to covertly disable a mine field)? is the weapon reliable enough to not go after a civilian cargo/passenger veseel when it should be going after a sub or enemy surface combatant? and, is it placed outside of fisheries zones where trawl nets may still be being used (god forbib a fishing trawler accidentally snags one and drags it up, detonating it, due to any anti-tamper devices)? There are also some european (Sweden and Norway) types, but I don't have much data there. A further web search may answer your questions.

That is why I specified 300 ft deep (or more) to prevent human tampering. (Besides they have to find it first.) Also, unlike the CAPTOR system this would be connected to a shore facility for power and control purposes. (this could make it more vulnerable) So unlike the captor it is not on automatic fire based on acoustical signature. This would be fired based more on land based or ship based radars. To protect against tampering, there are always tricks. Multiple lines from shore to the weapon, lines between weapons, and if all else fails, let go a pod to the surface to get satellite com, like our subs do. I'm sure there are others.

Sounds vicious...like a minefield on steroids. Something like SOSUS for eyes and ears, and large fat torpedoes vertically launched to just nail ships from the bottom. The biggest obstacle, IMO, is cost. It would be most useful in strategic locations such as Straits to ensure complete control over who goes through. For example...maybe Taiwan could set up a network like this...the hard part is extending it out to a useful range. It would be simple to set up in shallow water, but also fairly useless...you don't need expensive "super" torpedoes to shoot small shallow draft gunboats or landing craft.

I was actually looking to do something more defensive and a lot cheaper. No reason to control the whole strait area with this. Just control the last 15 miles to your coast. That means no big ships can get to your ports or landing zones. Killing little things like LCUs and LCMs are not worth a torpedo. They get a hellfire missile and they are gone.

they've already got the arrays, the issue is weaps. I'd ve more interested in seabed mines spowed within territorials. If you link them with the arrays and have real time processing, they could identify an enemy invasioon and start detonating. (more or less using a naval version of IFF) critical steps maybe: Seabed array seabed mines/"swimouts" array detects enemy presence sends release to mine in area mine floats to a preset depth (not surface) detonates calibrate sensitivity so that if the area is deemed hot, they can be "weaps free" autonomously via a hard command from land or satellite signal a tethered MK 48ADCAP would be better for large vessels (60+ knots is going to have a deleterious effect on a large vessel committed to a shore approach - unable to turn as the invasion beach will be busy with other vessels churning and burning) bubbling sub surface sea mines would make a hell of a mess of small vessels and landing craft.

The thing I like about using the MK48 ADCAP is the "claimed" range of nearly 20NM at 55kts. That would allow a few of these launchers to cover a major chunk of coastline. Reserve it for use against larger vessels. Probably only need to sink a dozen or two dozen bigger ships to take the starch out of an invasion. Smaller substations with the MK46 can handle smaller ships, like frigates and civilian stock. Not a big fan of mines, except for port entrances since they are stationary. Once you have a sense of where the amphibs are going to land you can deploy mines via sub, fast patrol craft or aircraft. Small stufff like LCMs and LCUs are perfect targets for hellfire missiles and artillery using area denile munitions. As you can tell I like to do things on the cheap ;) I was brought up on the Keep It Simple Stupid philosophy.

Mobile MLRS firing retarded, proximity (say 20m above sea level) cannister/shrapnel would make any landing party a bit twitchy.. ;)

Closer to shore would be a good use of MetalStorm technology. ;) They already have the area denial weapon system, to cover the beach area. If they had an airburst version to aim at landing craft.