Vessel types: Structure

Vessel type length

The length between perpendiculars of the vessel type. If the vessel length differs from this, then the vessel length and vessel type length are used to scale all the vessel type data to the length of the vessel, using Froude scaling.

Note: Some old OrcaFlex data files may contain vessels with the default value '~' for the vessel type length. This value is no longer permitted and will now cause an error if you attempt to run a simulation. In this case, you should replace the '~' with an appropriate value for the length of the vessel type. This value is only used if Froude scaling is required for any vessels of this type.

The remaining data on the structure page on the vessel type form are described below and are draught-specific, i.e. there are separate values for each draught. These data only affect the vessel motion if the vessel primary motion is set to calculated (3 DOF), calculated (6 DOF) or externally calculated.

Mass and moment of inertia tensor

The vessel type's mass and moment of inertia tensor with respect to axes through the centre of mass in the vessel x, y and z directions. These should include the structural and contents mass and inertia, but not the added mass, which is specified on the stiffness, added mass and damping page.

Centre of mass

The coordinates of the vessel type's centre of mass, relative to vessel axes.