Convention and notations¶
Two frame conventions are defined:
- North-West-Up (NWU) : used in seakeeping theory, the X-Y-Z axes are respectively North, West and Up directions.
- North-East-Down (NED) : used in manoeuvring theory, the X-Y-Z axes are respectively North, East and Down directions.
The frame convention has to be specified for all methods setting positions, velocities, directions of bodies, flows, etc.
Two direction conventions are defined:
A GOTO North direction is opposed to a COMEFROM North direction.
The direction convention is required for setting velocity flow, ship heading, wave direction, etc.