Need ID help for odd PNS rate patch

[David Minton]

A dealer I know hits me up for help with US Navy rate patches, and shared this one with me the other day. It came as part of a 150,000 patch lot he recently acquired.
 
I am completely stumped as I have never come across anything like this before. While the eagle looks USN from maybe 1930s, I couldn’t say with any certainty if it was even military. A guess is the letters are PNS, and abbreviation for Pxxxxxx Naval School or Nautical School. There was a Pennsylvania Nautical School during that period.
 
Sorry for the photos, as the patch is sealed in plastic.
 

 

 
 
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[joeclown]

Maybe naval Postgraduate School.....some sort of instructor