Hello Phil Pugliese,
 
Back when I was in the USN both boomers and fast boats have a device attached with a long cable that is designed to be manually or automatically released floating to the surface. On the surface the device, if every thing works, is a distress beacon that broadcasts effectively a mayday/SOS message. Once rescue ships arrive on scene a sound powered phone is connected for two-communications. The system is designed for relatively shallow waters around the coast line.
 
Tom R
 

From: "Phil Pugliese (via tml list)" <xxxxxx@simplelists.com>
To: "TML" <xxxxxx@simplelists.com>
Sent: Monday, February 15, 2016 6:35:50 AM
Subject: Re: Off-topic - tracking enemy vessels, was Re: [TML] Instant city

This email was sent from yahoo.com which does not allow forwarding of emails via email lists. Therefore the sender's email address (xxxxxx@yahoo.com) has been replaced with a dummy one. The original message follows:

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Anyone know what, if any, sort of 'beacons' the USN's sub's carry?
Any diff 'tween 'boomers' and the others?

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On Sun, 2/14/16, Peter L. Berghold <xxxxxx@berghold.net> wrote:

 Subject: Re: Off-topic - tracking enemy vessels, was Re: [TML] Instant city
 To: xxxxxx@simplelists.com
 Date: Sunday, February 14, 2016, 2:09 PM
 
 From what I remember of
 my time in the Navy you're correct ships don't go
 completely dark on the electronic spectrum during time of
 peace. However that said I can envision times during war
 where a ship would go dark on the spectrum including IFF and
 strictly use passive sensors to feel their way around.
 Certainly submarines even during peacetime use strictly
 passive sensors because they want to stay hidden even during
 the peace time.
 
 
 
 Peter L. Berghold <xxxxxx@berghold.net>
 
 Brewer, Gourmet Cook, Dog Sport Enthusiast, Navy Veteran
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