Woodstock74 wrote:Interesting, so the only possible visual indication of Prairie/Masker are what are effectively pipes I'm guessing running outside the pressure hull/exterior cladding?
Right. The hull emitters are often difficult to spot, but the stern ones are very apparent. Although it's not a fleet boat, this photo shows the aft piping on the Tang (the pipes look pretty much the same on GUPPYs):
Under Construction:
1/350 Typhoon
1/350 Skate
1/350 USS Nautilus
1/350 Tang
1/350 November
1/350 Hotel II
1/350 Alfa
1/350 George Washington
1/72 Type VIIC
Woodstock74 wrote:Interesting, so the only possible visual indication of Prairie/Masker are what are effectively pipes I'm guessing running outside the pressure hull/exterior cladding?
Right. The hull emitters are often difficult to spot, but the stern ones are very apparent. Although it's not a fleet boat, this photo shows the aft piping on the Tang (the pipes look pretty much the same on GUPPYs):
When did this system originally debut? Did the Soviets ever come up with something similar?
I'm not sure exactly when it was first at sea, but the idea appears to date from the 1920s, although the application was to provide an acoustic baffle for a destroyer sonar. The use of bubble curtains for quieting came right after WWII. I would guess that the GUPPYs got it around 1960, plus or minus five years maybe.
As for the Russians, I recall seeing a few things on some of their diesel boats that look like girth emitters, but I wasn't able to find much (I don't know what such a system is called in Russian).
Under Construction:
1/350 Typhoon
1/350 Skate
1/350 USS Nautilus
1/350 Tang
1/350 November
1/350 Hotel II
1/350 Alfa
1/350 George Washington
1/72 Type VIIC
My resin 1/350 version of a Guppy submarine is in the � What�s New� section. Unfortunately, the ModelWarships main page has not been updated to reflect the posting of my model as well as two additional models.
Tom Dougherty wrote:My resin 1/350 version of a Guppy submarine is in the � What�s New� section. Unfortunately, the ModelWarships main page has not been updated to reflect the posting of my model as well as two additional models.
Thought this would be of interest to some here, details of the passive sonar on the USS Cochino (some interesting images showing the streamlined sonar plus drawings as well as operating details). I hadn't seen this before, maybe it's also new to others:
Under Construction:
1/350 Typhoon
1/350 Skate
1/350 USS Nautilus
1/350 Tang
1/350 November
1/350 Hotel II
1/350 Alfa
1/350 George Washington
1/72 Type VIIC
Question about the use of the Prairie/Masker system used on GUPPYs. Looking at the elevation drawings of a number of GUPPYs I've noticed the masker system called out on the hull, but also on the the sail. Looking at pictures of the USS Razorback, Clamagore, etc you can see the masker line running down the side of the sail that is also called out on the drawing. I can understand the use of the masker on the side of the hull to quiet mechanical noise while snorkeling, but I'm more interested in the masker use on the sail. Was the sail considered a source of mechanical noise leak? I've only vetted the Atlantic sail contingent, but was the sail Masker also used on EB and Portsmouth sailed GUPPYs?
The Prairie Masker system's purpose was two-fold, taking advantage of sound transmission trying to pass through two very different mediums (air being 1/4 the density of water: Approx 1100 fps compared to 4800 fps.) The Masker attenuated own-ship's noise and degraded active sonar returns.
Prairie refers to the air released to reduce cavitation. Masker was the "bubble curtain" which enveloped the hull.
The sail is a huge flat surface whose sides reflects active sonar. Sound doesn't transmit through water to air to water efficiently as it tries to pass through bubbles. Some surface ship classes have employed versions of the system.
Anechoic tiles were the next evolution in external sound silencing and active sonar attenuation, in addition to acoustic countermeasures, which are launched when you've been snapped-up (detected); -another topic altogether.
Really good point about the surface area of the sail, hadn't thought about that.
Was the emitter pipe on both sides of the sail?
Additionally, I'm not seeing this on EB or Portsmouth GUPPY sails? Anyone know the history?
CC Clarke wrote:The Prairie Masker system's purpose was two-fold, taking advantage of sound transmission trying to pass through two very different mediums (air being 1/4 the density of water: Approx 1100 fps compared to 4800 fps.) The Masker attenuated own-ship's noise and degraded active sonar returns.
Prairie refers to the air released to reduce cavitation. Masker was the "bubble curtain" which enveloped the hull.
The sail is a huge flat surface whose sides reflects active sonar. Sound doesn't transmit through water to air to water efficiently as it tries to pass through bubbles. Some surface ship classes have employed versions of the system.
Anechoic tiles were the next evolution in external sound silencing and active sonar attenuation, in addition to acoustic countermeasures, which are launched when you've been snapped-up (detected); -another topic altogether.
Yes, the air emitter was on both sides of the sail. See attached photos of the late, great Clamagore with Masker piping indicated at red arrows.
Prairie-Masker was an addition to the Guppy subs and was not on the original versions. I don't know if the step sail versions (Electric Boat and Portsmouth sails) ever received the Master system. The Guppy III "Atlantic" plastic sail presented a large, slab like aspect to sonar and did receive the Masker piping.
