Acoustic measurement ships

Hibiki and Harima operate out of the major naval base in Kure, Hiroshima under the Maritime Self-Defense Force’s oceanographic command. Tokyo designates them as acoustic measurement ships, but their official English designation is “Ocean Surveillance Vessel.”

Unarmed, Hibiki and Harima are more like survey vessels than warships. They carry one of the most powerful sonar arrays in service—the AN/UQQ-2 Surveillance Towed Array Sensor System. Working alone and far from busy sea lanes, they unfurl long twin-line hydrophone arrays and patrol for months intently listening to long-range naval traffic.

Like much about Hibiki, SURTASS is American-made … and secret. Details of its effectiveness are classified, but SURTASS gained notoriety after environmentalists blamed its modern low-frequency active sonar component for killing marine mammals.

Like the broadly similar American Victorious class surveillance ship, Hibiki has a hydrofoil-like design known as SWATH—small waterplane area twin hull. This strange configuration looks like two submarines supporting an oil rig. It places the bulk of the ship’s displacement under the surface of the sea, resulting in a more stable ride at low speeds.

Hibiki differs from its American counterparts at its rear. It has a large aft helicopter deck to allow for resupply flights during long voyages. The Hibiki class has a reported mission radius of 3,000 nautical miles and can patrol for 60 to 90 days at a time. Having the ability to take on supplies by helicopter gives Hibiki a major logistical advantage over its U.S. Navy cousins.

The first of its class, Hibiki officially takes its name from a stretch of open sea off the coast of Kyushu, but the officers who named her clearly had alternative meanings of the word in mind.

In Japanese, hibiki means “echo,” emphasizing the vessel’s use of reflected sound to map and track the location and movement of submerged ships. But the name has even more relevance. Hibiki was also the name of Japan’s first all-welded ship—a Fubuki-class destroyer turned over to the Soviet navy as a prize of war in 1947. Choosing this name for the new ship was a middle finger to the Soviet Union, the enemy Hibiki was designed to face.