In The “Navigator Aries” [2023] SGCA 20, the Singapore Court of Appeal (the “CA”) clarified that Rule 9(a) of the International Regulations for Preventing Collision at Sea 1972 (the “Colregs”) requires a vessel proceeding in a narrow channel to keep as near to the outer limit which lies on her starboard side as is safe and practicable (the “Limit Requirement”), and not merely to keep to the “lane” that is on her starboard side (the “Lane Requirement”).

The Lane Requirement arose from Rule 25(a) of the 1960 Collision Regulations (the “Old Rule 25(a)“) which required a vessel in a narrow channel to keep to “that side of the fairway or mid-channel” which lies on her starboard side; this notionally divides a channel into a dual carriageway with vessels having to navigate on the “lane” to their starboard side. The question to be determined by the CA was whether Rule 9(a) of the Colregs maintains the Lane Requirement or replaces it with the Limit Requirement.

The CA considered the principles applicable to interpreting the Colregs (as set out by the UK Supreme Court in Evergreen Marine (UK) Limited v Nautical Challenge Ltd [2021] UKSC 6) and held that Rule 9(a) of the Colregs embodies the Limit Requirement for the following reasons:

a) The ordinary meaning of the wording in Rule 9(a) is different from the Old Rule 25(a) because:

  • the scope of Rule 9(a) is not limited to just power-driven vessels;the obligation in Rule 9(a) now applies to narrow channels and fairways independently; andthe obligation in Rule 9(a) now requires a vessel to keep “as near to the outer limit”, rather than to keep to the starboard side of the fairway or mid-channel as previously required in the Old Rule 25(a).

b) By requiring that vessels proceeding in a narrow channel achieve the widest clearance that is safe and practicable, the Limit Requirement gives effect to the object and purpose of the Colregs, being the promotion of safe navigation and prevention of collisions and close quarter situations.

c) The Limit Requirement is more flexible and situational, and better accommodates the diversity of localised concerns and changing conditions that narrow channels present.


The Limit Requirement gives effect to Rule 9(a) in a clear and practical manner and is capable of being understood by seafarers of all nationalities.

However, as the CA observed, this does not mean that the Lane Requirement has been abandoned. In practice, a vessel found on her port side of the channel would face difficulties establishing that she was far to the starboard limit as was safe and practicable, as she would be in an area that is likely to experience denser oncoming traffic flows.

This article was written by Jonathan Lim of Resource Law LLC

Reed Smith LLP is licensed to operate as a foreign law practice in Singapore under the name and style, Reed Smith Pte Ltd (hereafter collectively, "Reed Smith"). Where advice on Singapore law is required, we will refer the matter to and work with Reed Smith's Formal Law Alliance partner in Singapore, Resource Law LLC, where necessary.