Rule 20: Application
- Rules in this Part shall be complied with in all weathers.
- The Rules concerning lights shall be complied with from sunset to sunrise and during such times no other lights 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.
- 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.
- The Rules concerning shapes shall be complied with by day.
- The lights and shapes specified in these Rules shall comply with the provisions of Annex I to these Regulations.
What this means:
Rule 20: Application – Our plain English guide to help you understand & remember this rule.
This rule starts Part C: Lights & Shapes and introduces the overarching principles of when we should display appropriate shapes or lights based on the rest of the section. It also tells us that this part’s rules apply in all weather.
Day shapes
By day, vessels that need to declare their definition use shapes. This part of the rules defines all of them. The rules concerning shapes must be complied with by day, hence the reference ‘day shapes’.
When should we display lights?
Rule 20 tells us to display appropriate lights from sunset to sunrise and in restricted visibility, but it doesn’t say when to switch them off. There’s nothing to stop us from displaying appropriate lights all the time.
The rule says that we should display them if and when we feel it’s necessary, so if we believe lights may make us more visible to onlookers, we should switch them on.
Lights cannot be used instead of day shapes
We’re not allowed to replace appropriate day shapes with lights, so during the day, if we feel the visibility is poor and lights are a good idea, we should exhibit both day shapes and lights as appropriate.
