The U.S. Navy recently completed Full Scale Shock Trials (FSST) on one of its new 3,000 ton LCS type warships. These tests consist of taking one of the new ship types out to sea and temporarily replacing the crew with hundreds of instruments and cameras to record the impact of large explosions in nearby waters. These explosions are the largest ones the ship design was built to withstand. Not many details of each FSST are released. It was known that there were three underwater explosions in the LCD FSST, each consisting of a device with over four tons of explosives in it. The navy would not reveal how deep the explosions were or how far from the LCS when they went off. All these explosions appear to simulate naval mines. The most common mines these days being bottom mines that detonate while resting on the sea floor in shallow coastal waters. It was revealed that the LCS survived the tests with minimal (and expected) damage. The last FSST was conducted in 2008 for the new 25,000 ton San Antonio class LPD amphibious ships.
The only “stress testing” that is more punishing than an FSST is the SINKEX (sinking exercise) that intends to destroy the ship involved. For over a century navies have been using some of their retired ships for target practice to see how well they stand up to lots of damage. The U.S. Navy has also used old ships for target practice to see just how well recent design changes perform under realistic combat conditions. For example, most of the 30 decommissioned (from the late 1990s to 2005) American Spruance class destroyers were used for this kind of target practice. Running a SINKEX enables the navy to test some theories on how vulnerable, or invulnerable, modern warships are. Carriers are rarely employed for this but a 1996 SINKEX was conducted using the retired 82,000 ton carrier USS America. This classified exercise was a test of the vulnerability of such large ships to modern anti-ship missiles. While the exercise details were secret, it did get out that carriers this size were very hard to sink.