Convention and notations

Frame conventions

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.
../_images/frame_convention.png

Important

The frame convention has to be specified for all methods setting positions, velocities, directions of bodies, flows, etc.

Direction conventions

Two direction conventions are defined:

  • GOTO
  • COMEFROM.

A GOTO North direction is opposed to a COMEFROM North direction.

../_images/direction_convention.png

Important

The direction convention is required for setting velocity flow, ship heading, wave direction, etc.