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.

Reed Smith is in a Formal Law Alliance (FLA) with Singapore law practice Resource Law LLC. The FLA significantly expands Reed Smith’s offering in Singapore and our ability to service our clients’ legal requirements in handling multi-jurisdictional transactions, disputes, and cross border work involving Singapore law and the Singapore courts. The full service offering of the FLA includes advisory, transactional, corporate, and dispute resolution expertise in all of Singapore’s core industries and practices, including energy and natural resources, shipping, financial industries, insurance, regulatory, restructuring and life sciences.