Research Vessels: Submersibles - Trieste

Department of Navy Press Release

January 8, 1958

Navy Research Program Probes Depths Of Ocean To Two Miles In Bathyscaphe

Probing down to nearly two miles beneath the surface of the Mediterranean, Navy scientists completed a series of 26 dives in the Piccard bathyscaphe, the Trieste, off the coast of Naples between June 21 and October 25 in a research program sponsored by the Office of Naval Research, the Navy has announced.

The bathyscaphe, the creation of Professor Auguste Piccard, is the underwater equivalent of a lighter-than-air craft such as a blimp, operating in reverse. It consists of a 50-foot hull, 12 feet in diameter, filled with gasoline to make it buoyant, since gasoline is lighter than water. Beneath this hull is a suspended a sphere, 6.5 feet in diameter, constructed of forged "fatigueless" steel. This sphere, which easily holds two men and scientific equipment, is capable of withstanding ocean depths of more than three miles, which is about 20 times as deep as a conventional submarine. This permits the craft to explore about 99 percent of sea floors in the oceans of the world.

The hull above the sphere is built to withstand the buffeting of surface waves and towing but is not designed nor required to resist deep sea pressures because of the unique method of operation. The craft descends by letting sea water into air chambers in the hull. Entering through holes in the bottom, the sea water, which does not mix with and is heavier than the gasoline, maintains an even pressure between the hull and the outside sea. The normal rate of descent is about three knots. Ascent is made by jettisoning iron shot used as ballast. Additional control of the buoyancy is achieved by valving off small portions of gasoline.

The cabin has two portholes with windows made of six-inch thick plexi-glass. Three mercury vapor lamps attached to the sphere are used to light up the ocean depths. Some horizontal maneuverability of the bathyscaphe is provided by two battery-powered reversible propellers mounted on the hull. The Trieste is the second bathyscaphe designed and built by Professor Piccard. The first one, known as the FNRS3, is owned and operated by the French Navy. The name bathyscaphe is combined of two Greek words, "bathy" and "scaphe," meaning "deep boat."

The Office of Naval Research engaged the Trieste for a broad research program, involving acoustical and biological investigations of ocean depths. The long-range objectives of this program are to explore the ocean environment at great depths and to evaluate the potentialities of the bathyscaphe both as a research tool and as a naval craft, such as a submarine rescue vessel or a deep diving submarine.

In this particular series of dives the emphasis was on the study of the field of sound in the ocean growing out of the Navy’s great interest in underwater acoustics in submarine warfare. Investigations of the biology, geology, and physics of the ocean depths also were conducted in an attempt to identify sources of ocean sounds and to determine the sound transmission qualities of the ocean and the bottom.

One puzzling discovery was that at mid-depths the noise level differed significantly from that at higher and lower depths. It also appeared that this anomalous noise came from a horizontal rather than a vertical direction. In addition to acoustical measurements, there were many observations made of life in the mid-depths and on the bottom. An abundance of life was noted at all depths, including such strange species as fish whose bodies appeared to be covered with white down. The bottom often showed indications of burrowing animals. There were numerous holes in the ocean floor, most of them about one-quarter inch in diameter.

Piloting the Trieste throughout the program of dives was M. Jacques Piccard, son of Professor Piccard. Making the descents with him at various times were A.E. Maxwell and Dr. Robert Dietz of the Office of Naval Research; Russel Lewis of the Navy Underwater Sound Laboratory, New London, Connecticut; Dr. Andreas Rechnitzer of the Navy Electronics Laboratory, San Diego, California; and Morton Lomask and Robert Frassetto of the Hudson Laboratories of Columbia University. Four foreign scientists invited to participate in the program also made some dives.

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