By day, certain vessels are required by the COLREGS to exhibit various shapes, consisting of ball, cylinder, cone, and diamond. The ball is generally more than 1/2 metre in diameter and the other shapes are of comparable size. The size requirements are specified in COLREGS for larger ships and smaller vessels may use shapes that are scaled down to match their size.

These shapes are illustrated in the diagram and are used by vessels with characteristics as follows.Table of Shapes

1. A vessel at anchor shows a single ball.

2. A sailboat moving under power (motor-sailing) shows a cone with the apex pointing down.  A Canadian modifications to the COLREGS makes this shape optional for vessels of less than 12 metres. 

3. A vessel engaged in towing, if the tow exceeds 200m, will show a diamond shape. The towed vessel or object will show a diamond as well if the tow exceeds 200m.  

4. A vessel engaged in fishing will show two cones, apex to apex, in the shape of an hourglass.

5. A vessel not under command will show two balls. 

6. A vessel engaged in mine clearance will show three balls. One at the top of a foremast and one at either end of a yard below the first ball. All three in a triangle configuration.

7. A vessel restricted in ability to manoeuvre will show two balls with a diamond between them. When on a vessel engaged in towing there may be a separate diamond shape if the tow exceeds 200m. 

8. A vessel constrained by draft will show a cylinder. (Note that Canadian Modification Rule 28(b) means that you should not see this shape, or the corresponding light combination, in our local waters.)

9. A vessel aground will show three balls. 

10. A vessel restricted in ability to manoeuvre will show the ball-diamond-ball shapes and, if there is equipment obstructing a side, the blocked side will be indicated by two balls and the open side by two diamonds. 

11. A vessel engaged in fishing that has gear over the side extending more than 150m from the vessel will indicate the location of that gear with a cone with the apex pointing upwards. 

Flags Used as Shapes

Some vessels will show flags that signify meanings that are similar to the use of shapes.

A vessel engaged in diving will show a rigid replica of Flag ALFA from the International Code of Signals not less than 1 metre in height and ensure its all-round visibility. Other vessels should maintain a distance of 100m or more. A vessel engaged in underwater engineering, including diving, may display the ball-diamond-ball shape described above for restricted in ability to manoeuvre. 

A vessel that is taking in, discharging or carrying dangerous goods will show Flag BRAVO from the International Code of Signals. From time to time a barge carrying aviation fuels will be docked at the DND portion of the main wharf at Comox to make a delivery to the air base; you should see Flag BRAVO flying from the barge. 

In areas where there are divers in the water, the well-known divers flag may be displayed. This may not be on a vessel and may be flown from a post mounted on a small float. This flag is not part of the COLREGS, but is in common use. 

Last modified: Saturday, 1 November 2025, 2:38 PM