Submarines rely on stealth to survive. An alarming problem with the U.S. Navy’s submarine stealth has come to the surface. A Sept. 26 whistleblower complaint accuses shipbuilder Huntington Ingalls of falsifying quality tests on the stealth coating of Virginia Class attack submarines, thus “knowingly and/or recklessly” putting “American lives at risk.”
This anechoic coating, which reduces the submarine’s sonar signature, is called Special Hull Treatment in U.S. Navy parlance. In layperson’s terms these coatings are usually rubber tiles glued on to the outside of the steel hull. The process of attaching them and final finish varies by country and is a very sensitive topic which, understandably, isn’t talked about. If the coating falls off, the submarine can be detected more easily.
If true, the accusation could cost Huntington Ingalls millions of dollars. More alarming, it may have made the Virginia Class more vulnerable to detection because more of the coating may have fallen off along the way. The problem of the stealth coating falling off submarines is not new, and it is not unique to the U.S. Navy.
Submarines are made out of immensely strong steel, but when they go deep the water pressure makes their hulls flex and change shape. This places the adhesive behind the coating under immense strains. Add to this the long patrols, unforgiving salt water, rust and temperature changes involved and you have one of the most challenging operating environments on earth. So when you next see a submarine with tiles missing and rust stains, it may tell you more about the way it is being used than the maintenance standards of its owners.
Some British submarines suffer similar problems. The Russian Navy is often slow to replace tiles that have fallen off. Some Russian submarines, such as the Sierra Class attack boats, have titanium hulls, which seems to make the problem even worse. Sierra Class vessels have been sailing around for years with the same patches of missing tiles on the outside. These patches are so reliable that they can be used to identify the individual submarine.
But spare a moment for the submariners of the Iranian Navy. When Iran imported Kilo class submarines from Russia in the 1990s, they came with an anechoic covering. Iran’s drive for self-sufficiency has resulted in the submarines being maintained locally. Evidently the shipbuilding industry has a challenge reproducing the rubber tiles. They are often seen sailing around with most of the tiles removed, leaving a very uneven surface, which may greatly increase the noise signature of the submarine.