COLREGs Rules 4-5: Application and look-out in any visibility
Last reviewed: October 14, 2026
Rule 4 says the rules in this section apply in any condition of visibility. Rule 5 requires every vessel to maintain a proper look-out at all times. The look-out must use sight, hearing and all available appropriate means to fully appraise the situation and the risk of collision.
Applies toEvery vessel, in any condition of visibility.
What it says
International: The rules in this Section apply to any condition of visibility.
“Rules in this Section apply to any condition of visibility.”
Inland: Rules 4 through 10 (§§ 83.04 through 83.10) apply in any condition of visibility.
“Rules 4 through 10 (§§ 83.04 through 83.10) apply in any condition of visibility.”
Every vessel must at all times maintain a proper look-out by sight and hearing.
“Every vessel shall at all times maintain a proper look-out by sight and hearing”
The look-out must also use all available means appropriate in the prevailing circumstances and conditions, so the vessel can make a full appraisal of the situation and of the risk of collision.
“as well as by all available means appropriate in the prevailing circumstances and conditions so as to make a full appraisal of the situation and of the risk of collision.”
Common questions
Do the look-out rules apply in good visibility?
Yes. The rules in this section apply in any condition of visibility, and the look-out must be kept at all times.
“Rules in this Section apply to any condition of visibility.”
Which Inland rules apply in any condition of visibility?
Inland Rules 4 through 10 (§§ 83.04 through 83.10) apply in any condition of visibility.
“Rules 4 through 10 (§§ 83.04 through 83.10) apply in any condition of visibility.”
What must a proper look-out include?
A proper look-out must use sight and hearing as well as all available means appropriate in the prevailing circumstances and conditions. Its purpose is a full appraisal of the situation and of the risk of collision.
“as well as by all available means appropriate in the prevailing circumstances and conditions so as to make a full appraisal of the situation and of the risk of collision.”
The text of COLREGs Rules 4-5
U.S. Coast Guard, Navigation Rules and Regulations Handbook
Rule 4: Application; Rule 5: Look-out
International (COLREGs)
Rules in this Section apply to any condition of visibility.
Inland Rules
Application Rules 4 through 10 (§§ 83.04 through 83.10) apply in any condition of visibility.
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International (COLREGs)
Every vessel shall at all times maintain a proper look-out by sight and hearing as well as by all available means appropriate in the prevailing circumstances and conditions so as to make a full appraisal of the situation and of the risk of collision.
Inland Rules
RULES Conduct of Vessels in Any Condition of Visibility Look-out Every vessel shall at all times maintain a proper look-out by sight and hearing as well as by all available means appropriate in the prevailing circumstances and conditions so as to make a full appraisal of the situation and of the risk of collision.
Sections it refers to
The plain-English explanation on this page was written with AI from the regulation text above and checked automatically before publishing: every quote appears in the text, every number comes from it, and a second model confirmed each statement adds nothing the text doesn't say. Regulation text current as of August 12, 2024. The regulation text governs. RegKnot is not affiliated with the U.S. Coast Guard.