US conducts sinking exercise on ex-USS Ingraham frigate near Hawaii.

According to information published by the U.S. Navy on August 18, 2021, U.S. joint forces conducted coordinated multi-domain, multi-axis, long-range maritime strikes in the Hawaiian Islands Operating Area during a sinking exercise on the decommissioned guided-missile frigate ex-USS Ingraham.
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Oliver Hazard Perry-class ex-USS Ingraham frigate (Picture source: U.S. Navy)

Former Navy vessels used in sinking exercises, referred to as hulks, are prepared in strict compliance with regulations prescribed and enforced by the Environmental Protection Agency under a general permit the Navy holds pursuant to the Marine Protection, Research and Sanctuaries Act.

Each exercise is required to sink the hulk in at least 1,000 fathoms (6,000 feet) of water and at least 50 nautical miles from land and surveys are conducted to safeguard against harm to people or marine mammals during the event. Prior to being transported for participation in a sinking exercise, each vessel is put through a rigorous cleaning process for environmental safety and is inspected to ensure the ship meets EPA requirements.

Ex-Ingraham was a guided missile frigate commissioned on Aug. 5, 1989, and was decommissioned on Jan. 30, 2015. The ship was named for Duncan Nathaniel Ingraham and is the fourth Navy ship with the namesake. It is the second of its name to be used in a sinking exercise; ex-USS Ingraham (DD 694), which was decommissioned in 1971 and sold to the Greek Navy, was sunk in 2001.

The Oliver Hazard Perry-class is a class of guided-missile frigates named after the U.S. Commodore Oliver Hazard Perry, the hero of the naval Battle of Lake Erie.

The Oliver Hazard Perry-class ships were produced in 445-foot (136 m) long "short-hull" (Flight I) and 453-foot (138 m) long "long-hull" (Flight III) variants.

The Oliver Hazard Perry-class frigates were designed primarily as anti-aircraft and anti-submarine warfare guided-missile warships intended to provide open-ocean escort of amphibious warfare ships and merchant ship convoys in moderate threat environments in a potential war with the Soviet Union and the Warsaw Pact countries.