Clarification regarding the coordinate system in MoorPy

Wind & Water Computer-Aided Engineering Software Tools
1

Dear @Matthew.Hall,
Could you please explain the following terms related to MoorPy addBody

  1. reference point (where is the location relative to body reference frame?)
  2. body reference frame (located at the free surface level like WAMIT? or at CoG?)
  3. moment vector (about body reference frame?)

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Best regards,

2

Hi! Here’s a quick explanation:

  1. reference point (where is the location relative to body reference frame?)
  • The reference point is the origin of the body reference frame. I.e. wherever you put the body. And body properties are relative to this point. It’s kind of self-defined.
  1. body reference frame (located at the free surface level like WAMIT? or at CoG?)
  • The body ref frame origin is wherever you define the body to be. Same as x/y/z in the Body.r6 parameter, or the Body.setPosition method.
  1. moment vector (about body reference frame?)
  • Yes, the moments are relative to the body reference frame, i.e. the axes defined by the body roll/pitch/yaw entries in Body.r6.