Ship’s hull smoothing technique.

Updated: Mar 24, 2019

During the design of the vessel comes such a moment when it is necessary to make the workshop documentation for the construction of the hull of the vessel. With all the abundance in the market of ship surface design programs, the quality of the preliminary surface used in the initial stages of design, as a rule, does not meet the requirements of the shipyard

Voyager - Salt Ship Desing project, hull surface faired by MSI AS

The complexity of assembly and welding of ship structures depends very much on the quality of the hull surface, especially for the shell plates and profiles. High requirements to the quality of the ship surface pay off by reducing the time of assembling and fitting of hull structures and simplifying the bending of the shell plates and profiles

At this stage, the preliminary model of the ship surface gets to us in the company. Based on many years of experience in the smoothing of hundreds of hulls of different types of vessels, we have developed certain rules of operation and smoothing of ship’s hull. In this, we are greatly helped by the functionality of the system Shape Maker.

The basic principle.

The basic principle, which we are guided-as accurately as possible to repeat design ideas, and, at the same time, we try to remove all noticed defects of a surface and to achieve the most technological form of a case. We consider each new case as unique and try only to improve what was conceived by the designer.

3D model build on top of 2D lines.

Initial data.

As raw data for the hull smoothing, we can use almost any information from the lines drawing to any three-dimensional models of the hull geometry. When working on the restoration of old models, you can also use the table of offsets and scanned paper drawings, but this is more exotic cases.

Check initial lines before fairing.

Examine the source data to smooth the enclosure.

The smoothing process begins with the study of the source data, the identification of problem areas of the surface and the selection of surface areas where possible approximation with maximum accuracy. Changes made in the form of the original surface, which in our opinion can lead to a change in the hydrodynamic characteristics of the vessel or perhaps distort design of the designer necessarily agreed. Shape Maker, which is the main tool for surface smoothing has a very precise surface shape control tools, which allows revealing all possible defects of the original surface created by the designer. Tools such as visualization of inflection lines on a surface, visualization of sections by areas, compression of an image on one of the axes, the curvature of sections allow defining very quickly all possible problem areas.

3D Faired model.

Determines the optimal division of the hull into surface patches.

The next step is to determine the most optimal of the surface patches division of our model. All the main lines defining the geometry of the hull are necessarily considered. So, lines of a flat side, a flat bottom, knuckle lines are used as boundary curves for areas of a surface. We try to describe curved surfaces in one patch and avoid connecting curved patches with each other wherever possible. The exceptions are areas with a characteristic curvature along the connection line. This allows preserving the natural shape of the surface and the required smoothness along the connection line.

Surfac patch polygon.

Initial stage of fairing process.

The actual surface modeling begins with the boundary lines. A distinctive feature of the Shape Maker system we use is that at the initial stage of surface smoothing there is no need to approach the original curves and surfaces with high accuracy. The focus of this phase is on the uniform and natural distribution of control points on lines and surfaces. The topological model makes it easy to change the surface for example when refining the knuckle line shape. Thus, the surfaces adjoining to this line, naturally change the form. At this point, we try to approach the original surface using a minimum set of control points. Once this goal is achieved and it becomes clear that the number of control points is not enough, we increase their number. After those iterations are repeated again and again. An important feature of Shape Maker is that when the number of control points increases, the surface retains its original shape. This enables local surface modification in areas where it is necessary. The existing local smoothing and approximation functions make this process much easier.

Surface quality control toos in Shape Maker.

Inflection lines position determination.

The next step in surface smoothing is to determine the location and shape of the inflection lines by frames, waterlines, and buttocks. The inflection lines most accurately characterize the shape of the surface. This is one of the most important characteristics of the surface. The correct position of lines of inflections guarantees absence of undesirable inflections and waviness on any of the orthogonal sections. The shape of the inflection lines changes when the position of the surface control points changes.

Final fairing details.

Final fairing stage.

The final stage of surface smoothing is the local modification of the surface shape to smooth the curvature of the hull cross sections. In this case, the form changes are already so small that the modification of control points uses the scaled movement of the cursor and the control points are shifted only a few millimeters in real scale. It allows achieving the highest quality at smoothing hull surface.


The technology described above gives the best results in a fairly short time. The standard term of the hull smoothing for almost any complexity is one week from the moment of receiving of the initial information. At the same time, the customer receives an exclusive result, which does not cause any questions at any shipyard of the world.


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