Dear Colleagues,

Hi I am new with SACS, and am working on inertia loading generation with SACS tow module. I have some confusion with the notation system that SACS tow adopt.

Let's say we have conventional seakeeping coordinate system (X-surge, Y-sway, Z-Heave, with their corresponding rotation). For roll motion (+), the body inertia translation force will be in the opposite direction of the motion translation components. Hence, the inertia force should be in sway (+) and heave (+). However, the result from SACS tow suggests for such motion, the translation forces in sway (-) and heave (+) (see figure below). Anybody can help me to understand this? I could be wrong or lack of understanding in this case. Thank you for taking your time to read this problem, any help will be much appreciated.