Question 1

At night you see two white lights, one higher than the other, with red and green sidelights. The upper light is further from you than the lower. What is the vessel's aspect?

Accepted Answer

She is approximately head-on, heading towards you, with the lower forward masthead nearer, the higher after masthead further away, and both sidelights visible.. Seeing both red and green sidelights indicates a head-on or near-head-on aspect. The forward masthead light is lower and nearer to you, while the after masthead light is higher and further away. From astern, the sternlight is visible rather than the sidelights or masthead lights. From abeam, one sidelight is visible and the masthead lights may appear horizontally separated. Under COLREG Rule 23(a)(ii), a power-driven vessel underway of 50 metres or more must exhibit a second masthead light abaft and higher than the forward one. A vessel under 50 metres may also exhibit this second light, so two masthead lights do not establish that the vessel is at least 50 metres long.

Question 2

At night you see only a green sidelight ahead to starboard. No other lights are visible. What does this tell you?

Accepted Answer

You are viewing a vessel's starboard aspect; this light does not establish her type or give-way responsibility.. A green sidelight identifies a vessel's starboard aspect. Its prescribed sector extends from right ahead to 22.5 degrees abaft the starboard beam. Seeing this light without other visible lights does not establish the vessel's type, her precise course or which vessel must give way. Under Rule 15, when two power-driven vessels are crossing so as to involve risk of collision, the vessel which has the other on her own starboard side must keep out of the way. Seeing a green sidelight does not by itself establish that this rule applies.

Question 3

At night, you see only a red sidelight ahead to port. No other lights visible. What situation are you in?

Accepted Answer

She is showing her port side, likely passing red-to-red; keep watching her bearing for change. A red sidelight identifies the vessel's port side. With that light ahead to port, she may be passing red-to-red, but a single sidelight does not establish her vessel type, exact course or give-way responsibility. Keep watching her bearing and assess the risk of collision using every available means. A steady bearing with decreasing range indicates risk; apply the appropriate COLREG rule once the situation is established.

Recognition, questions and explanations

At night you see two white lights, one higher than the other, with red and green sidelights. The upper light is further from you than the lower. What is the vessel's aspect?

At night you see only a green sidelight ahead to starboard. No other lights are visible. What does this tell you?

At night, you see only a red sidelight ahead to port. No other lights visible. What situation are you in?

Practise this properly

Recognition, questions and explanations

Questions

At night you see two white lights, one higher than the other, with red and green sidelights. The upper light is further from you than the lower. What is the vessel's aspect?

At night you see only a green sidelight ahead to starboard. No other lights are visible. What does this tell you?

At night, you see only a red sidelight ahead to port. No other lights visible. What situation are you in?

Practise this properly