Can a boat sail anywhere it likes to block another boat?
A · Advanced · When boats meet · 4 of 12Mostly yes, with one limit. A boat that comes from clear astern and gets an overlap to leeward within two of its hull lengths may not sail above its proper course while that overlap lasts. Its proper course is the one it would sail to finish as soon as possible if the other boat were not there.
How it works
- Proper course: "A course a boat would choose in order to complete the leg she believes she is on as soon as possible in the absence of the other boats referred to in the rule using the term."
- Before the start: a boat has no proper course before its starting signal.
- The limit: if a boat clear astern becomes overlapped within two of its hull lengths to leeward of a boat on the same tack, it shall not sail above its proper course while they remain on the same tack and overlapped within that distance.
- The way out: it may sail above its proper course if in doing so it promptly sails astern of the other boat.
- Who is not limited: a leeward boat that got its overlap some other way, for example because the other boat came up from astern to windward, or after a tack.
Tricky cases
Can a boat have more than one proper course?
Yes. It is "a course", not "the course". Two good sailors may choose differently, and either choice can be a proper course if it is aimed at finishing as soon as possible.
A leeward boat luffs hard before the starting signal. Is it sailing above its proper course?
No. A boat has no proper course before its starting signal, so the limit cannot be broken then.
The windward boat sailed into the overlap from behind. Is the leeward boat limited?
No. The limit applies to the boat that came from clear astern and became overlapped to leeward.
Why the rule exists
Without the limit, a faster boat could dive in close to leeward of a rival and at once turn up hard, leaving the windward boat no fair chance to keep clear. The rule lets the overtaking boat pass and stops it using the pass as a weapon.
Where it differs
| Where | What changes | Source |
|---|---|---|
| Racing Rules of Sailing | As above | RRS 17; RRS Definitions (Proper Course) |
| Match racing and team racing | Appendices C and D change parts of the right-of-way rules. Not read | RRS Introduction |
From the rule book
World Sailing The Racing Rules of Sailing 2025-2028, rules 11, 16 and 17 and the Definitions (Proper Course). In force from 1 January 2025. Checked 14 October 2026. Official document: The Racing Rules of Sailing 2025-2028 (PDF).