Co-ordinate System

All the parts or objects of a ship or any other product described in AVEVA Marine are positioned in a co-ordinate system. A co-ordinate system may be local and positioned in other co-ordinate systems in hierarchies with any level of depth. However, in the end all local co-ordinate systems must be positioned relative to one global co-ordinate system that is located in the product in a well defined way.

In the case of the AVEVA Hull application the product is normally a ship or a ship like vessel. In that case there are rather strict rules for how the global co-ordinate system is located (see the figure below).

• The origin should be placed in the aft end of the ship, preferably in the bottom and in the symmetry plane (the Center Line plane (=CL)). It is a good practice shown in the figure (but not necessary!) to locate the origin aft of the ship so that all x-co-ordinates are positive. Another alternative is to place the origin at the aft perpendicular.

• The x-axis should be directed in the forward direction.

• The y-axis should be in the direction against portside.

• The z-axis should be in the upward direction (co-ordinates may be negative)

Planar parts of the hull model (for example, plane panels, brackets, ) are described in the uv-plane of local co-ordinate systems (uvw). These co-ordinate systems may be located quite arbitrarily in the ship co-ordinate system (xyz) of the ship. However, when the uv-plane coincides with a principal plane of the xyz-system the local co-ordinate system is as a standard positioned as shown in the figure below. In these cases the u- and v-co-ordinates will be identical to one of the x-, y- or z-co-ordinates which may be convenient. However, this is a matter of convenience and is in no way compulsory.

The co-ordinates are (in the Hull data banks) always expressed in millimeters.