The US Naval Institute Proceedings has an article recommending that the Coast Guard exploit acoustics to enhance its Maritime Domain Awareness.
The author provides some examples of how acoustics have proven this capability in the past.
“In 1961, the Navy successfully tracked the USS George Washington (SSBN-598) during her transoceanic voyage from the United States to the United Kingdom, demonstrating the ability to acoustically track vessels over global distances.”
It has found a limited application within the Coast Guard,
The Coast Guard already is using passive acoustic monitoring to autonomously detect critically endangered North Atlantic right whales and notify nearby mariners. Despite the program’s success, it has not expanded beyond the single Coast Guard facility in Woods Hole, Massachusetts. Leveraging this remote-sensing ability would allow the Coast Guard to reduce its reliance on expensive aircraft patrol hours while providing the same level of service:
It apparently could have been used to monitor fishing activity.
“A series of experiments supported by the Navy, Coast Guard, and National Marine Fisheries Service were conducted from 1992 to 1995 that explored the possibility of using SoSuS to track vessels fishing illegally. The experiment was a resounding success—results showed that SoSuS could be used to detect, identify, and monitor (this link is to a 468 page pdf — I did not see the article in question–Chuck) individual driftnet and trawling fishing vessels in the Bering Sea and northern Pacific Ocean. Despite promising results, the service failed to move to an acoustic-based enforcement approach.”
While I can find fault with the article, the author’s main thrust that the Coast Guard is not exploiting a part of the spectrum that could help maintain a picture of what is happening offshore is certainly true. Because we no longer have sonar or ASW expertise, we no longer have a window into what acoustic sensors have to offer.
While probably true that the Coast Guard might be able to establish acoustic surveillance over limited areas of special interest, if we are going to have a comprehensive system, we would likely have to ride the Navy’s coat tails.
A Navy system that listens for submarines could also listen for trawlers. It could detect vessels that have turned off their AIS. It might cue us that a terrorist controlled vessel is headed for a US Port; or that a merchant or fishing vessel is laying mines; or that a vessel is doing clandestine monitoring of our submarine operations.
This is also another way to track and identify vessels that may be illegally dumping.
This could even help with SAR. When I was an 8th District RCC controller in the early 70s, we had a tanker explode offshore, only we did not know that it had happened for several days. The day it happened we got a report of smoke. I sent an aircraft to investigate, but we found nothing but the smoke. Smoke was not uncommon, given all the offshore oil wells that flared gas. A few days later we got a report of a missing tanker. We searched and ultimately found its mast above water. It had been cleaning tanks closer to shore than it should have been, and had had a catastrophic explosion that ripped through 25 of its 27 cargo tanks. An acoustic monitoring system would almost certainly have picked that up. Anytime a ship sinks, the collapsing of bulkheads as air filled compartments are crushed should also be heard.
As the author points out, and as we have mentioned many times here, towed arrays on cutters could help us locate low profile drug smuggling vessels (drug subs).