To handle this new, considerably more complex and expensive task, it was decided that a new organisation was needed. The Mary Rose Trust, a limited charitable trust, with representatives from many organisations would handle the need for a larger operation and a large infusion of funds. In 1979 a new diving vessel was purchased to replace the previous 12 m (40 ft) catamaran "Roger Greenville" which had been used from 1971. The choice fell on the salvage vessel "Sleipner", the same craft that had been used as a platform for diving operations on the "Vasa". The project went from a team of only twelve volunteers working four months a year to over 50 individuals working almost around the clock nine months a year. In addition there were over 500 volunteer divers and a laboratory staff of about 70 that ran the shore base and conservation facilities. During the four diving seasons from 1979 to 1982 over 22,000 diving hours was spent on the site, an effort that amounted to 11.8-man-years.