Rule 20 - Application

Please note: The following information has been reproduced from Part C (Lights and Shapes) of the Prevention of Collision at Sea Regulations 1983 (external link). The purpose of the reproduction is to explain "graphically'' the requirements of navigation lights on a variety of vessels.

1. Rules in this part shall be complied with in all weathers.

2. The Rules concerning lights shall be complied with from sunset to sunrise, and during such times no other light shall be exhibited, except such lights as cannot be mistaken for the lights specified in these Rules or do not impair their visibility or distinctive character, or interfere with the keeping of a proper look-out.

3. The lights prescribed by these Rules shall, if carried, also be exhibited from sunrise to sunset in restricted visibility and may be exhibited in all other circumstances when it is deemed necessary.

4. The Rules concerning shapes shall be complied with by day.

5. The lights and shapes specified in these Rules shall comply with the provisions of Annex I (Positioning and Technical Details) to these Regulations.