Question 1

A power-driven vessel of 30m underway at night. What is the minimum she must display?

Accepted Answer

One masthead light, sidelights, sternlight. Rule 23(a): a power-driven vessel underway shall exhibit a masthead light forward; sidelights; and a sternlight. The second masthead light (abaft and higher) is required for vessels of 50m or more. Vessels under 50m require only ONE masthead light. Vessels under 12m may combine into a single all-round white + sidelights.

Question 2

A power-driven vessel of 75m underway. How must the two masthead lights be positioned relative to each other?

Accepted Answer

The after masthead light must be positioned abaft and higher than the forward masthead light.. Rule 23(a)(ii) requires the second masthead light to be exhibited abaft and higher than the forward one. Their relative positions help an observer determine the vessel's aspect. When viewed from directly ahead, the lights appear vertically aligned. Masthead lights have a prescribed arc of 225° and are not visible from directly astern. Annex I specifies their vertical and horizontal separation.

Question 3

A power-driven vessel of 8m underway at night. What is the minimum lighting requirement under Rule 23(d)?

Accepted Answer

An all-round white light AND sidelights, OR may exhibit a combined lantern showing sidelights and masthead light. Rule 23(c)(d): a power-driven vessel of less than 7m in length whose maximum speed does not exceed 7 knots may exhibit an all-round white light and sidelights if practicable. Rule 23(d): a power-driven vessel when underway may, in lieu of prescribed lights, exhibit an all-round white light and sidelights. For vessels under 12m, Rule 23(c) allows a combined lantern showing masthead + sidelights + sternlight in one fitting.

Rule 23, questions and explanations

A power-driven vessel of 30m underway at night. What is the minimum she must display?

A power-driven vessel of 75m underway. How must the two masthead lights be positioned relative to each other?

A power-driven vessel of 8m underway at night. What is the minimum lighting requirement under Rule 23(d)?

Practise this properly

Rule 23, questions and explanations

Questions

A power-driven vessel of 30m underway at night. What is the minimum she must display?

A power-driven vessel of 75m underway. How must the two masthead lights be positioned relative to each other?

A power-driven vessel of 8m underway at night. What is the minimum lighting requirement under Rule 23(d)?

Practise this properly