You and another boat are both on port, running side by side. A starboard-tack boat comes up from behind and heads for the gap between you. Do you have to let her through?
Yes. Under Rule 10, when boats are on opposite tacks a port-tack boat keeps clear of a starboard-tack boat, and that holds downwind too. "Clear astern keeps clear" is Rule 12, and it only applies to boats on the same tack. The starboard boat does not need to ask for room either: World Sailing Case 23 says Rule 19 does not apply to a starboard boat passing between two port boats on a run, and Rule 10 makes both port boats keep clear of her. Her one limit is Rule 16.1: if she changes course, she must give the port boats room to keep clear. Everyone must still avoid contact if reasonably possible (Rule 14). Port keeps clear, even downwind, even from behind.
📖 Want Rule 10 in more depth? Elvstrøm Explains the Racing Rules 2025-2028 sets out every rule with plain-English explanations and diagrams. (affiliate link)
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<p><a href="https://sailing.kiwi.nz/v/or6Q3awqh2o/">Source: Sailing Kiwi</a></p>Go deeper: books and gear
- Racing Rules Companion 2025-2028 by Bryan Willis — Spiral-bound pocket guide to the current rules.
- Elvstrøm Explains the Racing Rules 2025-2028 — Every rule, with plain-English explanations and diagrams.
- Five Oceans masthead wind indicator — See the wind direction at a glance.
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