"That said, Deep Siren is supposed to be just the first generation of a lot of new kit which will finally, properly bring the lone-wolf submarine captains under the heel of shore HQ like everyone else."

Yeah, right on, brother. It passes info to them, they have intelligence enough of their own as to what they will do with it. Have you seen the state of shore environments? ...... Does, couldn't organise a piss up in a brewery, leap to mind?

Nice idea though.

Of course, this wouldn't be necessary had the ELF aerials not been down. What can ELF be used for I hear you cry? Paging submarines...

Why would you assume that anything would be left unencrypted?

I am sure they will be using proper encryption and time encoding on messages.

Transmission by acoustics is no different than airwaves as far as security goes.

Chances are the device will not even be capable of decrypting the messages, just relaying them.

The enemy couldn't intercept or forge messages, however jamming the radio or acoustic waves would be possible if they are nearby.

My question is why they wouldn't implement a bidirectional link, or they are but aren't talking about it.

Obviously it would give away the location of the sub, but it'd be nice to have the capability.

It seems more than a little ironic that the system will probably use acoustic encoding similiar to what is used on standard telephony modems, which I've heard reffered to affectionatly as "whale song" before.

...of helping non-allied fleets determine that a US sub is not too far away.

@ Jon Green:

You're absolutely right. A non-allied fleet would know that the US Government thinks their sub is within 50 miles of the buoy, so hey, they only have to cover more than 150 square miles of ocean.

50 miles is probably not even close to accurate though. It's probably much more. Ohio class ballistic missile subs cruise at 20 knots*, so if it really was a 50 mile radius, the sub would cross it in less than 5 hours.** So either the range is significantly higher, or they'd drop several buoys, or both, which dramatically increases the area in which an enemy fleet would have to search. Given the stealthiness of US submarines, one could be within a mile of you, and you'd probably never know it. The terms needle and haystack suddenly spring to mind.

* The unclassified speed. Also, Los Angeles class fast-attack subs cruise at 20-25 knots, and Seawolf class subs cruise at 25+ knots. The seawolf has a maximum published speed of 35 knots (40 mph) while submerged.

** Keep in mind a nautical mile (6,076 feet) is longer than a statute mile (5,280 feet)

Back in the 1960s our US destroyers had underwater telephones. Not only could we talk ship-to-ship but we could talk to the porpoises. Trust me, the porpoises were much more fun and sometimes seemed to make more sense. Wooop, weeep, werrrp. I'll get me macintosh (we ARE underwater after all).

> My question is why they wouldn't implement a bidirectional link, or they are but aren't talking about it.

Um, because an acoustic homing torpedo wouldn't need too much reprogramming to follow the sub's comms rather than a ship's prop wash?