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254 THE MARINE REVIEW Booby PLAN | SHEER PLAN. ie = Oe ee to be ea ee c 6 F OO ea a 2 a eee ee oe ee ee S | eM S . : S SECTION OF e o | mh HARPIN 3! | t os [| 3 ; I | , BASE LINE _ So | => eet 0 ~The HALF BREADTH PLAN || points determined for them from the oH Beh a Soe T body plan, hence, as yet, these plans <4 74 , do not quite agree with each other. 'We may now proceed to correct the body plan from the half-breadth plan by reversing the preceding process, and thus draw new square stations in the former plan, having previously rubbed out those originally drawn. But it is found advisable, before doing this, to institute. a greater check upon the square stations in the body plan, than can be made with level lines only. This is done by projecting and rabatting upon half-breadth plane the intersections of the diagonal planes, already drawn, with the surface; and by projecting upon the sheer plane the intersec- tions, with the | surface, paraliel to that plane. The two sets of lines obtained by treating the diagonal planes as. described, are termed diagonal lines and horizontal ribband lines respectively; while the lines obtained by the intersections of the planes parallel to the sheer plane, are known as bow lines when in the fore body, and buttock lines when in the after body. The diagonal lines and horizontal tibband lines are valuable as checks the of planes 6 5 HALF SHOING OF HEEL 3 NO DE NA "Ss 'a /HOOLE LINE JR2e2 e FIG. 8-DIAGRAM SHOWING METHOD OF DRAWING A HORIZONTAL RIBBAND LINE \ upon the fairness of the ship, inas- niuch as, being in planes which are nearly perpendicular to her surface, they give more determinate inter- sections; besides which, they afford an excellent criterion of the nature of that surface. Lines Used for Testing The bow and _ buttock .lines are valuable only at the extremities of the ship; "and, there, more as- 'a criterion by which the experienced draftsman can decide whether or not the character of the surface is such as it should be, than as a means of fairing the body, owing to the general indeterminateness of their intersec- tions. : Hence, some draftsmen test the fore and after ends of the ship by bow and buttock lines, before pro- ceeding to fair the body; as it some- times happens when the body has been carefully faired by level lines, by. "running in" a few bow and but- tock lines,:<a; "radical. defect. in. the character of the surface is discovered, which necessitates a repetition of the whole fairing process. Before proceeding to fair the body by means of the diagonals, or lines of heads and heels of timbers, it must be remarked, that as neither of the Boby PLAN INIT FIO ~ enw en ee ae ae ae ee ih i a i sia ee lee ee Kee le ee Ce a os Ee ae SHEER PLAN = _--_------ { FIG. 9-BUTTOCK LINES AND BOW LINES | j