Optional: There are other approaches possible to building a hull. For example, you could continue to smooth the hull by using SrfMerge (Surface/Edit Tools/Merge) between the sides and the transom. Click hereif you want to see some other interesting approaches to modeling hulls.

13 Modeling a Sailboat: Rails
The red line in figure below indicates the surface edges of the hull. The steps on this page will show how to create an elliptical rail following this outline.

DupEdge (Curve/From Objects/Duplicate Edge) the top of the hull sides. There is already a curve at the top of the transom, so select and Join the three curves.

Maximize the perspective view.

The two rail curves need to extend far enough to be trimmed back using the bow stem as the cutting object. Use the Extend (Curve/Extend/Extend Curve) command on the rail curve at the bow. At the 'select boundary edges' prompt, hit Enter. At the 'Select object to extend' prompt, select the rail curve and pull a line out off the end of the rail curve.

Put an Ellipse (Curve/Ellipse) near the end of the rail, use the 'AroundCurve' option (A) and hit Enter. Drag the width, or numerically specify the width by typing 4, and then enter 2.5 as the height of the rail.

Select the edge curves, and the curve that is at the top of the transom, and hit Join.

Hit Sweep1 (Surface/Sweep 1 Rail) and select the rail as the path and the ellipse as the cross section curve. Use the 'Roadlike-top,' and 'Refit within .01' options. Notice that the rails extend beyond the top edges of the hull.

Select the two long rails and hit RebuildSrf. Give the rebuilt surface 10 U point and 4 V points.

Select the shorter transom rail and RebuildSrf it with 3 U and 4 V.

14， Modeling a Sailboat: Rails

Go to the top view and zoom in on one of the stern corners.Select the stern rail and hit ExtractIsoparm 'Direction=V' and extract an isoparm from the stern rail where it meets the side rail. Extract an isoparm from the side rail the same way as shown below.

Split off the ends of the rails with the extracted isoparm and Emerge (Analyze/Edge_Tools/Merge Edge) the edges.

Check out Options/Units and make the 'Absolute tolerance' 0.1.

NOTE: The Absolute tolerance is an important adjustment that can influence the quality and the efficiency of your models. If you set the absolute tolerance to a higher number, such as 0.5, then the higher number would actually produce a lesser degree of accuracy, and the edges might not be perfectly fitted together. Conversely, if you were to make the tolerance too exacting, for example by using a setting of 0.01, it could create an unnecessarily dense surface. As a general rule of thumb, you will often find it most efficient to use a higher number for the absolute tolerance when building fillets, and use a lower number when creating blends.

Delete the small ends of the rail and also delete the curves that were used for splitting.

Blend between the two rails: be sure to flip one the directions by entering F, and clicking on one of the points.

Hit Show, zoom in on the bow, and use the Split command. When prompted to 'Select objects to split,' pick one of the two rails. When prompted for the cutting object, select the keel.

Repeat on the other rail.

The rails are now complete. Be sure to save your work before continuing.

15 ，Modeling a Sailboat: Deck
Save your file and merge the b7.3dm file or open boat7.3dm

The red line below shows the edge of the deck, which is where the rub rails go. Rub rails are lower exterior rails that serve as a sort of side bumper for boats.

Turn on the 'picture frames' layer and replace the sections.jpg with the side.jpg using PlaceBackgroundBitmap (View/Background Bitmap/Place) and then turn off the layer.

Turn on layer 'annotate5' and trace over the #1 curve in the background image and trim it off at the hull ends.

NOTE: The curve #1 in the background image may be difficult to see, because several areas of the curve are poorly reproduced on the blueprints. This curve runs down the middle of the boat (from the top view) and forms the crown or curvature of the deck.

Note: Line #2 is the same line we made earlier and forms the edge of the deck from where we jumped ahead in the backbone construction section. Refer to the blue line shown below.

Trace over the #2 curve and Trim it off at the hull ends.

Project it to both hull sides.

Select the three curves and Loft with normal and 'Rebuild with 8 control points' as shown below.

Save your work

16 ，Modeling a Sailboat: Rub Rails
Rub Rail

The red line below indicates the location where a protective "rub rail" will be built.

Select the Pipe (Solid/Pipe) command, click on the edge of the deck and use a value of 1.5 for both the beginning and end radius.

A boat could actually look this way, but the pipe currently ends rather abruptly at the bow stem. As an alternative to the first method, you could Dupedge the side of the deck and Extend (Curve/Extend/Extend Curve) the curve until the pipe ends inside the bow stem.

NOTE: Capped pipes can create a lot of mesh geometry if the cap is joined to the pipe. If you are exporting the boat as a mesh, explode the pipes first, but don't delete the caps.

Create a new layer with the name 'rails' and ChangeLayer the rub rails to that layer.

Save your work. The hull and deck are complete.

17， Modeling a Sailboat: Deck Detail / Cabins
Save your file and merge the b8.3dm file or open boat8.3dm. The file b8.3dm contains many of the curves used to create the deck detail objects on the 'deck details' layer, and are there for reference or use at any time.

The red lines shown below indicate the cabins going by the plans.

Draw rectangles around the cabins, and on the left-hand cabin turn on CV's and Scale1D (Transform/Scale/Scale 1-D) the left most points towards the center. Explode (Edit/Explode) both the rectangles and Fillet (Curve/Fillet) the corners with a 'Radius' of 4.

From the perspective view hit Split the deck with the filleted rectangles.

NOTE: The curves don't actually have to be on the deck surface to get a Split. Projection from the construction plane is automatic, so since the CPlane in the Perspective view is the same as the Top view you can split the deck with the curves from the perspective view as shown below.

18 Modeling a Sailboat: Deck Detail / Cabins

Important Note: It is necessary to ShrinkTrimmedSrf (Surface/Edit Tools/Shrink Trimmed Surface) the cutout part of the surface before you ExtrudeSrf (Solid/Extrude Surface) them up to the height of the rail. To see what ShrinkTrimmedSrf does, select the cabin top and control points PtsOn, notice that the control points go all the way out to the edge of the deck, defining a larger surface than is needed. Turn off the points, use ShrinkTrimmedSrf, and note that the geometry will be cleaner and less likely to give you bad objects (SelBadObjects) after filleting.

Select the trimmed deck surfaces and ExtrudeSrf (Solid/Extrude Surface) with 'Cap=Yes' option and drag them up to the height of the rail.

Explode the new cabins and Delete the bottom surfaces.

Select the cabins and the deck and hit JoinSrf.

Hit FilletEdge (Solid/Fillet Edge) the tops with a 'Radius' of 3.

Hit FilletSrf (Surface/Fillet) where the cabins meet the deck with a 'Radius' of 3.

Note: To check for mistakes, hit SelectBadObjects (Analyze/Diagnostics/Select Bad Objects) after making fillets.

Put a Pipe (Solid/Pipe) on the lower edge of the fillets with a 1 'Diameter' shown below.

Select the cabin rails and ChangeLayer them to the 'rails' layer.

Save your work.