This chapter deals with the estimation of the main ship dimensions (lengthLength, beam, draft, side depth), following the first estimation of ship’s displacement, and of other basic ship design values and hull formHull form characteristics (hull form coefficientsHull form coefficients, powering, weight components, stability and trim, freeboardFreeboard, load line), as required in the first phase of ship design, i.e., the Concept DesignConcept design. The various effects of specific selections of ship’s main dimensions, etc. on ship’s hydrodynamic performance, ship’s stability and trim, her structural weightWeight and constructionConstruction costConstruction cost, utilization of spaces and transport economy are elaborated. The selection procedure is supported by statistical data and empirical design formulas, design tables, and diagrams allowing direct applications to individual ship designs. Besides the comprehensive list of references at the end of this chapter, additional reference material (statistical design diagrams) is given in Appendix A.