This paper describes new methods of principal particulars design and hull construction members design for small workvessels.
　The conventional procedure to design principal particulars of a small workvessel is as follows:
　A type ship is selected among many workvessels and its principal particulars are modified to satisfy design conditions such as velocity and length. The procedure consists of long and complicated steps, and not a little data on principal particulars are needed. The authors investigated characteristics of principal particulars of current workvessels and analyzed the correlations among them. Then, on the basis of those results, the authors proposed an easy procedure for principal particulars design.
　Hull construction members should be designed to satisfy the rules and design conditions. This procedure is trial and error, needs a detailed midship section and a general arrangement. The authors developed computer programs in order to simplify this design process. These programs are composed of the formulas which were obtained through the analysis on the specifications of current workvessels, and need only a few design terms and a very rough midship section.