Since 1979 the Wolfson Unit has been supplying computer programs that enable naval architects to perform accurate calculations, over a range of design problems, on their office computing facility. The Unit has many years of experience in applying the programs to the calculation of stability and other design data for unusual and complex hull forms as well as for conventional ship types. The program packages include comprehensive documentation that allows the user to gain the maximum benefit from the system without requiring experience in computer techniques. These packages are backed up by the comprehensive advisory services of the Wolfson Unit staff and their continuing programme of software development.