Why are submarines so hard to detect even with modern equipment?
In: Engineering
_~~Cobb~~ COB, I was just teaching_ seaman _Beaumont here the intricacies of modern sonar.._ Yeah, I ain’t Cheif of the Boat, Im Sheena, Queen of the jungle.
So, there are two types of sonar. One is active. You send out GIANT acoustical pings like a whale or dolphin use for echolocation and they bounce off another submarine, or ships, or rocks or schools of fish. Give you a very clear picture of what’s underwater. Now, whether or not it’s a loud reverberating CLONG like in Red October, Ill leave to an actual submariner, but the problem with active sonar is… well, its loud. It gives away YOUR position as much as the bad guys, so we’re not gonna talk about it here.
Passive sonar is just listening to sounds transmitted through the water. Problem is, the sea is _extremely loud_. And noises, particularly low-frequency ones, travel quite a long way. So if you are lucky to pick the sound of noise out of the clutter of the surface waves, the squid and fish and methane bubbling out of volcanic vents, it could be a ship or submarine that is very very far away (_Including one waaaay out of Pearl!_). So lots of computer processing is needed.
On the other hand, naval surface ships to some degree, but submarines as a matter of course, have been designed for the past 80 years specifically to be as quiet as possible. Anything that can vibrate, cavitate, or make any noise is isolated from the outer skin of the hull by an air gap or rubber padding or both. The hulls of submarines are streamlined and smooth, possibly coated with sound-absorbing/dampening rubberish material, and designed to sleekly open a gap in the water ahead of them and let the water merge back together behind it. Stealthy like.
Nuclear submarines have a lot of motors and pumps and stuff that have to run continuously, so they’re actually quite noisy (the tradeoff is they don’t need fuel for decades). When they talk about a diesel submarine sneaking up and killing a carrier say, what they mean is a Deisel electric submarine, running on its batteries and electric motors only. The diesel engine is off and is only used out of battle to recharge its batteries.
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