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Quick article on raft mountings in submarines

covert_shores

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I have some photos of raft mountings in the Swedish Nacken Class SS, and although it is well known that submarines use raft mountings to reduce their noise signature, there is next to no information on the internet (I think!). So I thought I'd compile a short article on this very elusive topic. http://www.hisutton.com/Submarine_Stealth.html





If you know of any more info or photos please share and I can improve my article for others.
 

Trident

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Great article! I seem to remember having downloaded some graphics on Russian raft-mountings/dampers, I will try to find that info and share it.

EDIT: Here's what I found so far, the source (which I no longer recall) connected the image with the 885 SSN project. Difficult to judge without a human figure reference, but perhaps seems a bit small for that? Note how not only the entire enclosure is insulated, but also the equipment modules and pipe connections against the intermediate floor between upper and lower levels.
 

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phil gollin

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.

Although resilient mounting of equipment in ships as protection against vibration and shock was widespread, raft mounting was originally developed by the Royal Navy not for submarines but for silencing of coastal minesweepers against acoustic mines. The results were so spectacular that the RN decided to add it to SSNs. They shared their designs with the USN who picked up the idea.

There are conflicting accounts as to which navy got a raft to sea first (but certainly the first generation designs did differ, the RN needed to be locked to develop full power whereas, again accounts vary, over whether USN ones did). RN second generation ones were able to develop full power without being locked.

"Noise Hygiene" however was a very complicated issue. Especially with the first few classes of SSN/SSBNs different ships within classes had slightly different acoustic signatures due to building errors and refits often included remedial works. Even nowadays self-monitoring is extremely important to pick up "shorts".

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covert_shores

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Thanks both, great info. Will add to the article.

Any views on when Swedes got in on the game? Possibly independent development. I have been told that they were the first (or among first) to double raft their boats in 1970s.

Have some cool articles on Swedish sub projects in the works. :)
 

Trident

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Just to add that I have found the source again, which includes a proper attribution of the image which you can now add to your article:

http://www.secretprojects.co.uk/forum/index.php/topic,6544.0.html

(I had a feeling I got it from hereabouts - where else would you find gems like that ;) Hat tip to both Paul and flateric!)
 

Trident

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Some more bits and pieces:

http://www.navyrecognition.com/index.php/news/naval-exhibitions/2018/euronaval-2018/6642-euronaval-208-hutchinson-stractive-active-noise-and-vibration-control-system-for-submarines-and-ships.html

https://www.hutchinson.com/en/marine-propulsion-raft-mount
 

stealthflanker

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In case anyone interested to a "bare" raft without machinery mounted.



From Norman Friedman's "Submarine Design and Development" Page 137.


oh and nice work on the article :D
 
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