Principles of naval engineering - Historic Naval Ships Association

Chapter 2-SHIP DESIGN AND CONSTRUCTIONFigure 2-32.— Body plan of a YTB.147.29BODY PLANTo visualize the projection known as the bodyplan, we must imagine the ship's hull cuttransversely in several places, as shown inpart A of figure 2-31. The shape of a transverseplane intersection of the hull is obtained at eachcut; when the resulting curves are projectedonto the body plan (part B of fig. 2-31) they showthe changing shape of transverse sections of thehull.Since the hull is symmetrical about thecenterline of the ship, only one-half of eachcurve obtained by a transverse cut is shown onthe body plan. Each half curve is called a halfstation . The right-hand side of the body planshows the forward half stations— that is, thehalf stations resulting from transverse cutsbetween the bow and the middle of the ship.The left-hand side of the body plan shows theaft half stations— that is, the half stationsresulting from transverse cuts between thestern and the middle of the ship.As may be inferred, a station is a completecurve such as would be obtained if each transversecut were projected completely, ratherthan as half a curve, onto the body plan. Thestations are numbered from forward to aft,dividing the hull into equally spaced transversesections. The station where the forward endof the designer's waterline^ and the stemcontour intersect is known as the forwardperpendicular, or station O. The station at theintersection of the stern contour and the designer'swaterline is known as the after perpendicular.The station midway between theThe waterline at which the ship is designed to floatis known as the designer's waterline.31