public void goAboard(Boardable toBoard, World world) {
    if (aboard != null) aboard.setInside(this, false) ;
    aboard = toBoard ;
    if (aboard != null) aboard.setInside(this, true) ;
    
    final Vec3D p = this.nextPosition ;
    if (! aboard.area(null).contains(p.x, p.y)) {
      final Vec3D pos = toBoard.position(null) ;
      pos.z += aboveGroundHeight() ;
      setHeading(pos, nextRotation, true, world) ;
    }
    if (verbose) I.sayAbout(this, "NOW aboard: "+aboard) ;
  }