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Choosing Which Surface to Use

(Marine Design)

Masts, spars, daggerboards, flat rectangles Q: Can you make the surface by sliding one curve along another? If yes: The simplest surface you can use is a Translation Surface. In this surface the moving curve stays parallel to its initial position.
Keel bulb is foil revolved around axis Q: Can you make the surface by rotating one curve around a centerline or axis? If yes: You can use a Revolution Surface.
Aluminum, steel, or plywood construction Q: Do you want to be able to build your surface out of a flat plate and to fabricate it by bending alone? That is, is your surface required to be developable? If yes: Use a Developable Surface.
Floor of deck-house taken from deck Q: Is the surface a piece of a larger surface? If yes: Use a SubSurface or Trimmed Surface.
Wings, keels, rudders Q: Are you making an airfoil or a hydrofoil? If your surface will be attached to another surface, use one of the other lofted surfaces with Foil Curves for master curves.
Sides of deck-house, surfaces of trapezoidal keel Q: Do you need a simple, somewhat “flat” surface to span the distance between two curves smoothly? If yes: A Ruled Surface probably will meet your needs. If you want to expand it into a flat plate you can use a Developable Surface instead.
Sails, round-bottomed hulls Q: Do you think of the surface as being the area inside three or four boundary curves? If yes: Use a Tangent Boundary Surface.
Decks, chine hulls Q: Do you want the surface to be freeform, but fixed to two edge curves (the sheer line and chine for example)? If yes: There are two choices: you can use a Ruled Surface, or a B-spline Lofted Surface.
Hulls, rounded bows, general surfaces We often use a C-spline Lofted Surface running through transverse B-spline Curves for boat hulls. This is a good combination between the flexibility of B-spline curves for the transverse direction and the stiffness of cubic splines longitudinally.
Lofted surfaces from measured points Q: Do you need a surface to pass through a net of control points exactly? If yes: Try a C-spline Lofted Surface defined by C-spline Curve master curves.