[Milsurplus] Cheap manual for AN/BSQ-3A (INTREPID)

[Nick England]

Got a nuclear attack sub? Need a manual for your AN/BSQ-3A (INTREPID)?
Just $5 to cover postage

Wot's a BSQ-3A (INTREPID) you ask? Receiving-Recording Set, Special -
Consists of two bow transducers, two sail transducers, some processing
electronics (0.5-5.5 Hz)  and a chart display.
The operational capabilities and limitations can be found in the
SECRET supplement (sorry, not included). This manual says "for
tactical purposes, the system is NOT designed to detect and process
signals that are produced by snorkeling, shallow running, and surface
running targets."  "It is designed to operate independent of other
electronic detecting systems employed aboard nuclear attack submarines
of the SSN 594, 637, and 688 class."

One reference on the web says " It was designed to detect the minute
cavitation bubbles left in the ocean by a submarines screw. Theory
held that the bubbles would stay entrained for up to 24 hours. Thereby
allowing them to be detected and start setting a track based on where
a sub used to be. The detection system worked in only that it could
detect the bubbles, the downside is that in practicality the odds of
intersecting a trail at the right depth and the right time was
astronomical, the ocean's are a pretty big place after all. Secondly
even if you intersected such a trail, maintaining the track as it
gently floated to the surface is a bad idea."

Fascinating, Captain....

cheers,
Nick
www.navy-radio.com