Keeping Submarines Quiet

I had the good fortune of attending a Lake Superior Elders presentation given by Dr. David Baumann covering naval warfare.  He’s a professor at Lake Superior State University.  This topic was extremely interesting and the presentation was informative.  I was given a lot food for thought.  Dr. Baumann started the presentation with discussing the 50 anniversary of the Cold War between the U.S. and Russia.  The following questions were answered:

1.        What is sound?  Sound is referred to as a series of compressions and rare factions which are air particles moving through the air at approximately 345 meters per second, several football fields. Sounds are either in high pressure or low pressure areas and it is amazing according to Dr. Baumann that pressure is very small. 

2.       What is noise cancellation? This is adding “Anti-Noise” which can actually make sounds worse in other areas.  If there is no vibration, there is no sound.  The goal is to get rid of the vibration.  There was a picture shown of two amplifiers one emanating one sound and the other emanating an opposite sound. That concept was a little confusing to me.  What is an example of an opposite sound?

3.       What is sound in water?  Sound travels faster in water at 1500 meters per second.  The greater the pressure the deeper you are in the ocean.  When we were singing songs on the beach while camping, people who we could barely see in a fishing boat told us that we sounded good.  Does sound travel over water faster also?

4.       How do submarines make noise?  There is machinery noise from pumps, reduction gears, and power plants.  There is a flow noise, higher speeds cause more noise.  Cavitation noise is referred to as the sound caused by air bubbles made by the propellers.  Having an uneven number of propellers creates less sound, 3, 5 and 7 are the common number of propeller blades that are used.  They don’t use 4, 6, or 8 blades.  Every submarine has a “signature.”  By listening to the engine moving and timing the seconds a submarine creates a noise the navy can determine what submarine it is.  The formula is if the engine is moving: 5x’s/ seconds at 5 perks.  I think I got that right when I was taking notes.  The process involves locating submarines and learning what their vulnerabilities are.

5.       How are submarines detected? According to Dr. Baumann, sound is referred to as SONAR by the navy or Sound Navigation Ranging which involves just listening with hydrophones. Sound is bouncing sound signals off the ocean floor to scan the ocean floor and then they can find what direction another submarine is in.  A description was shown of sound waves being sent directly to the ocean floor in a diagonal pattern and then bouncing off the ocean floor and deflecting against another submarine under the surface of the ocean. 

6.       How do we keep submarines quiet? This is top secret.  All submarines contain nuclear weapons. Congress is speculating why it is so important to keep so much secret from Russia, there isn’t a Soviet Union anymore.  There are better ways in which to spend $2 Billion.  The U.S. has more countries after us than Russia does.  There was a discussion about the SOFAR channel which also involved a waveguide. A channel in which Russia had to travel to get to the U.S. had a tracking system set up in various locations to detect where Russian submarines were.  Russia figured where these locations were.  SOSUS, which was referred to as Sound Surveillance System, was used to detect submarines.  This program was started in the early 1960s and was put into place to monitor Soviet attack submarines.  Now this system is used for research and is used to monitor whales. The scientists discovered using this system the mating calls of whales.  The system was declassified so the knowledge of this system is open to the public. 

The presentation was ended by discussing a recent incident involving a Soviet Submarine and how the crew parished on the submarine because they couldn’t be rescued.  The location of the submarine could not be given away.