"Kuroshio", Undersea Observation Chamber, a New Weapon for Submarine Geological Works

Abstract

A new submarine research chamber named "Kuroshio" which belongs to the University of Hokkaido was built in 1951 for the purpose of studying oceanography, biology and fishery visually at the undersea. It was planned and designed by Prof. N. Inoue (Hokkaido University) and R. Oaki (International Marine Engineering Co.), under the guidance of Prof. U. Nakaya (Hokkaido University), with the help of Dr. T. Sasaki (Scientific Research Institute). Most parts of it were constructed by the Tsurumi shipyard (Nippon Steel Tube Co.) and accessories such as window glasses, underwater lightings, guages and instruments were provided by several makers.
The "Kuroshio" is 3.15m. in height (to the top of the hatch cover), 3.70m, in length (from the tip of wooden bearer to the end of the direction stabilizer fins) and 1.48m, of outside diameter of the observation chamber, with total weight of almost 5, 000kg, with accessories. It has one main observasion window with controlable reflector, one seabottom observation window and three side and rear windows Lighting equipments are well prepared for submarine observation and for photographying. It is hung down from a mother ship by suspending wire and electric cables for light and telephone will serve as second hunging wire when necessary.
Tow or three persons are able to work in the chamber operating instruments, making scientific observations and taking photographs from the window. They always communicate by telephone with the bridge of the mother boat, talking everythings what they saw, what it happened and giving orders to each other. The endurance of staying at the undersea is about 10 hours for 2 persons aided by the oxygen feeder and CO2 absorbing unit. Its safe diving depth is 200m, below sea surface as it is designed to make surveying on the continental shelf, although it is durable under the pressure of 400m, sea depth. The suspended "Kuroshio" is usually slowly propelled by the drifting or slowly moving of mother ship and able to stand still at the sea bottom when the mother ship is anchored.
Important scientific results were obtained by the "Kuroshio" since 1951 at various areas around the Japanese islands. Among biological works, observations on "marine snow" (snow flake like suspending aggregates of disintegrating corpses of planktonic micro-organisms) were well done and habitats of many kinds of bottom fishes and benthonic animals, burrows and piles of them were fully recorded. In the field of fishery, behaviers of trawl net fish traps and plankton net under operation, nature of fish culture bed and effects of light for fishing were investigated, while optical and sonologic studies in the undersea and turbid water observation were made in physical oceanography.
The present author tried to operate the "Kuroshio" for submarine geological surveying since 1953 and found it to be a very useful tool for the purpose. In the Ishikari Bay of Hokkaido, several types of ripple marks under formation and some mode of occurrence of marine shells were seen at the sea bottom, suggesting us its usefulness on studying marine sedimentation. In the Tsugaru Strait between Honsho and Hokkaido, where a project of railroad tunnel driving is now under planning by the Japanese Government Railway, kinds of rocks and every geological formations exposed on the seafloor were fully identified by naked eye from the window. And it lead us to believe that it will be possible to draw geological route map of the seafloor by continuos, linear observation on the "Kuroshio" by slow moving and even making geological map when routes are effectively selected. This submarine geological work will be done more efficientry in cooperation with bottom rock sampling by dredging method.