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Research Vessel KAIYO

Research Vessel KAIYO retired on February 2016.
KAIYO was built in 1985 to be used as the underwater operations vessel for the New Seatopia Project, which involved experiments in deep-sea saturation diving, and performed numerous operations with a high degree of precision up until 1990. It is currently used as an underwater research vessel, mainly carrying out investigations of the sub-bottom structure.


  • Support research dives of the deep ocean floor survey system, DEEP TOW
  • Structural surveys of the deep-sea bottom
  • Seafloor topography surveys


Semi-submerged catamaran
KAIYO is a semi-submerged catamaran or SWATH-type vessel. It is therefore only minimally affected by waves, allowing work to be performed safely and efficiently onboard. The deck surface area can provide workspace for a range of experimental and observational instruments.
Dynamic Positioning System (DPS)
When moved about by waves, wind and ocean currents, KAIYO is able to autonomously compensate and maintain a fixed position based on information obtained from GPS systems and acoustic transponders. The DPS is extremely effective when used in the deployment of DEEP TOW, which must be towed at a speed of 0.3-0.5 knots, to determine water temperature and to deploy salinity measurement equipment and CTDs, and is also useful when taking samples of deep-sea water from a depth of 6,000 m or by each ocean layer.
Ocean Bottom Seismometer Refraction Method System
KAIYO is equipped with an Ocean Bottom Seismometer Refraction Method System used to analyze the sub-bottom structure. The system employs an air gun to produce artificial seismic waves, and seismometers to measure these waves after they are refracted and reflected in the various layers of the Earth's plates. By analyzing the data obtained, the structure of the Earth's crust can be determined in detail up to several tens of kilometers below the surface.
New Seatopia Project
The New Seatopia Project was a series of diving experiments that began in 1985, and in 1988 a diver succeeded in performing a dive test at a depth of 300 m. Up until the final dive test performed in 1990, the project made large contributions to the field of pressurized diving through the development of diving technology, and by establishing technologies and diving systems for underwater operations under the harsh conditions found at depths of 300 m.

Principal specifications

Length 61.5 m
Beam 28.0 m
Depth 10.6m
Draft 6.3 m
Gross tonnage 3,350 tons
Cruising speed Approx. 13 knots
Range Approx. 6,200 nautical miles
Accommodation 60 (29 crew, 31 research personnel)
Main power generation system Diesel engines: 1,250kw × 4
Main propulsion system Induction motors: 860kw × 4
Main propulsion method Controllable pitch propeller × 2