Answer:
Wave motion module allows entering vertical and horizontal accelerations as during shipping:
The software will simply apply whatever acceleration indicated for transverse and longitudinal loading but for vertical loading the weight will also be added automatically to the vertical motion load, see below.
Longitudinal load = mass x motion load acceleration provided by user in longitudinal direction
Transverse load = mass x motion load acceleration provided by user in transverse direction
Vertical load = weight of vessel + (mass x motion load acceleration provided by user in vertical direction)