The scope of this Recommended Practice is to establish acceptable three-coordinate reference systems for marine vehicles. Each coordinate system will include a defined origin, specified axes of rotation, and a sign convention in order to establish uniformity in mass property data collection and reporting. The use of a standard coordinate system will minimize the possibility of error due to differences in coordinate systems used by suppliers, designers, builders, regulatory bodies, or owners. These coordinate systems will be used in the determination of centers-of-gravity. They will also be used to determine weight moments of inertia as they relate to the three rotational degrees of freedom: roll, pitch and yaw.