<P> The results were inconclusive, as three weeks of surveying in almost continuous bad weather during July and August 1980 failed to find Titanic . The problem was exacerbated by technological limitations; the Sea MARC sonar used by the expedition had a relatively low resolution and was a new and untested piece of equipment . It was nearly lost only 36 hours after it was first deployed when the tail was ripped off during a sharp turn, destroying the magnetometer, which would have been vital for detecting Titanic's hull . Nonetheless it managed to survey an area of some 500 square nautical miles and identified 14 possible targets . </P> <P> Grimm mounted a second expedition in June 1981 aboard the research vessel Gyre, with Spiess and Ryan again joining the expedition . To increase their chances of finding the wreck, the team employed a much more capable sonar device, the Scripps Deep Tow . The weather was again very poor, but all 14 of the targets were successfully covered and found to be natural features . On the last day of the expedition, an object that looked like a propeller was found . Grimm announced on his return to Boston that Titanic had been found, but the scientists declined to endorse his identification . </P> <P> In July 1983, Grimm went back a third time with Ryan aboard the research vessel Robert D. Conrad to have another look at the "propeller". This time nothing was found and very bad weather brought an early end to the expedition . It later turned out that Sea MARC had actually passed over Titanic but had failed to detect it, while Deep Tow passed within 1.5 miles (2.4 km) of the wreck . </P> <P> D. Michael Harris and Jack Grimm had failed to find Titanic but their expeditions did succeed in producing fairly detailed mapping of the area in which the ship had sunk . It was clear that the position given in Titanic's distress signals was inaccurate, which was a major expedition difficulty because it increased the search area's already - massive size . Despite the failure of his 1977 expedition, Robert Ballard had not given up hope and devised new technologies and a new search strategy to tackle the problem . The new technology was a system called Argo / Jason . This consisted of a remotely controlled deep - sea vehicle called Argo, equipped with sonar and cameras and towed behind a ship, with a robot called Jason tethered to it that could roam the sea floor, take close - up images and gather specimens . The images from the system would be transmitted back to a control room on the towing vessel where they could be assessed immediately . Although it was designed for scientific purposes, it also had important military applications and the United States Navy agreed to sponsor the system's development, on condition that it was to be used to carry out a number of programmes--many still classified--for the Navy . </P>

How long did it take the titanic to reach the bottom