Introduction Copy

Vessel Heirachy Pyramid

This introductory lesson looks at a simplified version of the different categories of vessels, how to identify them during the day and night, and how their responsibilities to avoid a collision differ (rule 18). The diagram below shows the different categories of vessels in a hierarchy pyramid. In a collision scenario, each category must give way to the categories above them in the pyramid, except in an overtaking situation. A copy of the full IRPCS has been included as a final topic here and students are encouraged to study further to get an understanding of its detail.

Light Arcs of Illumination

Sidelights

Sternlight

Masthead Light

Combined