COLLISION AVOIDANCE LIGHTS, SHAPES AND FOG SIGNALS


During the day it’s usually quite easy to judge the size, type, speed and course of another vessel, but that’s not the case at night. To make this possible all vessels carry distinguishing lights after dark. Even in daylight a vessel might be engaged in some activity that isn’t very obvious. In those circumstances, a vessel must display a shape or shapes – always black – to signal what’s going on.


Sound signals are most commonly made with a ‘whistle’ – better known as a ‘fog-horn’ when talking of large ships. They aren’t as informative as lights or shapes but they do give some indication of what might be out there with you and in what direction danger might lie. A ‘short blast’ means one approximately 1 second long. A ‘prolonged blast’ should be somewhere between 4–6 seconds.


Lights are characterised by their colour and the arc through which they can be seen (Fig 7:3). Obviously, ‘all-round’ lights can be seen through 360°.


They are:


■ Masthead light A white light that can be seen from dead ahead to 22.5° abaft the beam on either side – a total arc of 225°. Vessels over 50m must carry two as shown below.


■ Sidelights Often called ‘port and starboard lights’. The port light is red and can be seen from dead ahead to 22.5° abaft the beam to port. The starboard light is green and displays over the same arc to starboard.


Fig 7:3 The basic lights are intended to indicate in which general direction another vessel is heading.


7


View from dead ahead


View of port bow


View of starboard bow


■ Sternlight A white light – usually mounted aft – displaying through an arc of 67.5° from dead astern on both sides – a total of 135°.


Note that the sternlight fills in the ‘gap’ left by the masthead light. This means that if you can see the stern light, you shouldn’t be able to see the masthead light or sidelights. Conversely, if you see a sidelight and masthead lights, the sternlight should be invisible to you.


RYA Seamanship for Sea Anglers


51


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