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.There is only oneisoparm in each direction and one at each edge.The reason this geometry is so simple is that you rebuilt your curves before youperformed the loft.The simplicity of these surfaces is going to make it easy to fair thishull.Each time you move a point, the isoparm corresponding to the nearest stationwill change.Since, on the bottom, you have the station curves  behind the isoparms,you can see how much you are deviating from your preliminary stations.131 Rhino Marine: Offshore Racing Power BoatNote: The side could have been lofted the same way as the bottom, but was done asit was to demonstrate how easily a surface could be constructed from only threecurves.Step-by-Step: Loft the hull surfaceLoft the surfaces1 Make the cHull layer current.2 select the sheer and upper chine and the midgirth curve.3 Start the Loft command.4 In the Loft Options dialog box under Style, select Normal.5 Select all the bottom stations.6 Repeat the Loft command.7 In the Loft Options dialog box, click OK.Lofted surfaces.8 Save your work.Adjust the surfaceAt this point, you should look at how fair your surfaces are.Look at a magnification ofthe curvature of each isoparm and analyzing how it looks relative to its neighbors.Ifthe isoparms do what you expect and progress from one station to the next in agradual transition, then you can assume that the surface is reasonably fair.For now, select the surfaces and turn on curvature graph and points.In the imagebelow, you can see the curvature graph for the surfaces on the outside of the hull.Surface control points and curvature graph.This image shows the isoparms on the model are quite fair.You will not need to moveany control points to achieve fairness in this model.132 Rhino Marine: Offshore Racing Power BoatStep-by-Step: Adjust the surface control pointsTurn the curvature graph on1 Select the lofted surfaces.2 Use the CurvatureGraphOn command to display the curvature graph.3 Use the PtOn command to display the control points of the surfaces.Surface curvature graph.Modify the bottom surfaceSince you took some liberty earlier in causing your hull to cross centerline intonegative space, you should inspect the results.Surface in right viewport.If you zoom in on the Right viewport, you may see that the inboard edge of the loftedbottom surface has a tendency to cross the centerline.Surface crosses centerline.133 Rhino Marine: Offshore Racing Power BoatTo fix this, edit control points in this area to cause the entire surface to cross thecenterline.Surface problem solved.Trim the surface to a vertical centerline in the Right viewport.The trimmed hull bottom surface.The inboard edge of the hull surface should resemble the forefoot from the designer slines drawing.Since you did not use the stem and forefoot in your controllinggeometry, how close will the resemblance be?As you can see from the image below, the trimmed surface is almost a dead match forthe forefoot that came from the designer s lines.You can judge whether the surfaceneeds any further modification.The trimmed hull.134 Rhino Marine: Offshore Racing Power BoatHowever, what about the body plan? How closely do your lofted surfaces fit thestations you inherited from the lines drawing in the beginning of this exercise?Lofted surface isoparms and body plan stations.As you can see, we have made only minor modifications to the surface.The originalintent of the stations is achieved.Step-by Step: Fix the forefootMove the control points1 Select the bottom surface.2 Turn on the control points with the PtOn command.3 In the Right viewport, move control points until the inboard edge of the bottomsurface crosses the centerline.Move surface control points to make the surface cross the centerline.Keep your eye on the stations (in other viewports) to be sure the isoparmscontinue to match them as you modify the surface.4 Press Esc to turn off the control points when you have successfully nudged theinboard edge into negative space.Trim to the rabbet1 Start the Line command.2 At the Start of line & prompt, type 0,-3.3 At the End of line & prompt, pick a point in the Right viewport above the tip ofthe sheer.135 Rhino Marine: Offshore Racing Power BoatDraw a vertical trimming line.4 Select the vertical line.5 Start the Trim command.6 At the Select object to trim & prompt, select the bottom surface inboard ofthe cutting edge.The trimmed bottom surface.7 Check your work against lines in the profile and body plan.Profile lines and hull bottom.136 Rhino Marine: Offshore Racing Power BoatLofted surface isoparms and body plan stations.8 Save your work.Construct the chine strakesNow that you have built the side and bottom surfaces, adding the three surfaces thatmake up the chine is simple.Copy from Hull Lines.3dm the 2-D curves thatrepresent the vertical surface between upper and lower chine strakes, use theCrv2Views command to create the 3-D curves.Rebuild the curves [ Pobierz całość w formacie PDF ]

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