Clause 6 Shapes
Maritime Rules Part 22: Collision Prevention
(1) Shapes must be black and of the following sizes—
(a) a ball must have a diameter of not less than 0.6 metres;
(b) a cone must have a base diameter of not less than 0.6 metres and a height equal to its diameter;
(c) a cylinder must have a diameter of at least 0.6 metres and a height of twice its diameter; and
(d) a diamond shape must consist of two cones as defined in Appendix 1.6(1)(b) and having a common base.
(2) The vertical distance between shapes must be at least 1.5 metres.
(3) In a vessel of less than 20 metres in length, shapes of lesser dimensions, but commensurate with the size of the vessel, may be used and the distance apart may be correspondingly reduced.