Royal Belgian Institute of Marine Engineers Bathyscaphe Trieste by Dennis Bryant A revolutionary diving craft, leading the way for future generations. The first ultra‐deep diving manned vessel was conceived, designed, and constructed by August Piccard, a Swiss physicist in 1947. He called the craft a bathyscaph, coined by combining the Greek words bathos, meaning deep, and scaphos, meaning ship. In 1952, he began construction of a more advanced version. Because it was built largely in the city of Trieste, he named it TRIESTE when it was launched on August 1, 1953. It consisted of a small pressure sphere about seven feet in diameter attached to the underside of roughly rectangular float chamber that was 59 feet long and eleven feet wide. The whole thing looked distinctly unseaworthy. That is because the craft was never designed to transit on the surface of the water. Rather, its sole purpose was dive deep and return to the surface. The float chamber was filled with 22,000 gallons of gasoline. This flammable liquid was selected for two reasons: first, it was lighter than water; and second, it was nearly incompressible, even at extreme pressure. The float chamber also was fitted with two ballast silos filled with 18,000 pounds of magnetic iron pellets. These pellets were to be released when the two‐ man crew wanted to ascend to the surface. Having no means of propulsion when on the surface, the Trieste had to be brought to a point almost directly above its target and then allowed to descend. The craft made various dives in the Mediterranean before it was purchased by the US Navy in 1958 for the sum or $250,000. The Navy made various modifications, including the development and attachment of a stronger pressure sphere. The new sphere had one cone‐shaped acrylic glass observation port. Quartz arc‐lights were also attached to illuminate the dark depths of the ocean. After several test dives, the Trieste was taken to waters in the Pacific Ocean over the Challenger Deep, the deepest known point in the world’s oceans. There, on January 23, 1960, the Trieste, with Jacques Piccard (son of August Piccard) and Lieutenant Donald Walsh, USN, descended to the bottom 37,800 feet below. The descent took almost five hours. They spent twenty minutes on the bottom, observing a number of small sole and flounder. The ascent took over three hours. Immediately after the loss to the nuclear submarine Thresher (SSN‐593) on April 10, 1963, the Trieste was moved to the Atlantic Ocean. On June 29, 1963, it located wreckage of the Thresher at a depth of 9,600 feet approximately 220 miles east of Boston. After that, the Trieste was retired and replaced by more capable vessels. Source: Apr 24, 2012 www.maritimeprofessional.com .