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# Modeling thrusters. Practical example.

Updated: Apr 29, 2020

Typically, the intersection of the thruster pipe and the hull is formed into a conical ring. The outer border of the ring lies on the surface of the hull, and the inner on the pipe of the thruster. The most common are two varieties of thrusters rings. In the first case, the line of connection of the ring to the outer shell is a circle, in the second case, an elliptical curve. The construction of models for each type of surface has slight differences. In principle, the construction of this type of surface is not a problem for most CAD systems. Some of them do it faster, but in this case we are creating a model that updates its geometry when changing the model parameters and can be reused by copying from the old project to the new one.

The entire simulation process can be described in several steps. The geometry of the thruster is taken from the drawing. As a rule, when constructing, a ring with legs 100x100 millimeters is used. This corresponds to the thrusters of vessels 50-70 meters long.

1. We create a new block in which our model will be located. In principle, this is an optional condition. You can create your model in existing blocks. This will simply greatly facilitate the structuring of information in the project. It will also make it easier to copy our bow thruster to a new project.

2. We build the axis of the thruster pipe on which the main geometry of the project will be built later.

3. Build the thruster pipe. It must be remembered that the thickness of the pipe is goes inside hull, so the theoretical surface of the pipe will correspond to the outer diameter.

4. We build the outer contour of the thruster cone like a pipe that will intersect with the outer skin. According to our drawing, the diameter of this pipe should be increased by 100 millimeters from the diameter of the thruster. It is important to set this pipe with a color that can be turned off later, since this surface is auxiliary.

5. Create an equidistant surface shifted 100 millimeters into the hull shape. This surface is also auxiliary and must be specified by the color of auxiliary elements.

6. We build the line of intersection of the thruster pipe with the equidistant surface. This will be the inner border of our cone.

7. We build the line of intersection of the outer contour and the hull surface. This line will be the outer border of the cone. I recommend choosing a different color for the intersection lines. I usually choose dark red. Intersection line cannot be edited directly. Its shape changes when the shape of the intersected surfaces changes. Therefore, highlighting the line with color will help other participants in the project to better understand the model.

8. Build the surface of the cone, based on the borders. Note that pipes in Shape Maker are built from two surfaces. Accordingly, the intersection of such a pipe with other surfaces will have two lines of intersection. Before setting the surface of the cone, the corresponding points on the outer and inner borders of the cone must be connected by straight lines.

9. Cut the surface by the intersection lines.

10. Turn off auxiliary surfaces by turning off the corresponding color in the thruster unit.

The model we created will vary depending on the change in the diameter of the thruster pipe and the shape of the hull surface. It is quite simple to modify existing model to have results like it is shown below. You can also move or copy thruster model into new location. If new thruster have a different geometry it is easy to change it.

Video below show real process of thruster surfaces modeling.