She was built as a replacement for the dilapidated . In terms of design, it is said to be an expanded and improved version of the submarine rescue mother ship , and while abolishing the submarine mother ship function, it is strengthening medical equipment. For
DSRV operation, the basic configuration of having a
moon pool in the center of the
hull is the same as the 56AS, but the
poop deck has been extended to the vicinity of the
bridge structure, and the
standard displacement has been increased by 1,800 tons. As a result, the equipment that was previously stored in the exposed part can now be accommodated inside the ship. In addition, attention was paid to high-speed cruising ability so that the vessel can quickly advance to the distress site, a
bulbous bow was adopted to reduce wave-making resistance, and a ship bottom closing device was installed at the bottom of the center
well. This is a method of opening and closing the closing plate divided into two by hydraulic pressure, and structures such as a sliding type and an inward opening type were examined, but due to the certainty required for the mission of rescue, the double door method by opening outward was adopted. The main engine is equipped with two
Mitsui Engineering & Shipbuilding 12V42M-A
diesel engines. This is the same series as the in-line 8-cylinder engine that was the main engine in
Chiyoda, but the output was increased by using a V-type 12-cylinder engine. As a propulsion device, in addition to two
variable pitch propeller axes, two side thrusters are provided on the
bow and
stern. Like
Chiyoda, they are equipped with a
dynamic positioning system (DPS), which allows them to stand still at a point on the ocean. ==Construction and career==