As described in Equivalent Mass Properties, the Mass should be defined so that the behaviour of the Dynamic Point is realistic, particularly in the time domain. Unless the overall scale of the hydrodynamic model is small, the Mass of the Dynamic Point should not be small.

One exception to this would be where the Dynamic Point is connected by a Joint to a Part; however, the range of masses over all structures in the model should be less than 4 orders of magnitude (meaning a maximum 10,000x difference between the smallest and largest masses).

While the physical mass should be represented by the Mass value, which introduces inertia and gravity force to the Dynamic Point, you can also use Added Mass to create inertia (only) in specific freedoms.

The Aqwa Workbench editor checks that some constraint is applied to the Dynamic Point. For example, you will see a warning when you solve the Hydrodynamic Diffraction analysis if the Dynamic Point has a Mass which is larger than the Displaced Mass, and there is no connection to prevent it from falling freely due to gravity.

Although Dynamic Points do not have any effect on the results of a Hydrodynamic Diffraction analysis, a change in the properties of a Dynamic Point will cause the Hydrodynamic Diffraction Solution to go out of date. This is because the hydrodynamic database created by the Aqwa solver needs to include the latest Dynamic Point properties before any Hydrodynamic Response calculations are performed. However, the Hydrodynamic Diffraction system should be relatively quick to update, as the radiation-diffraction calculation will not be repeated.