Rule 10 — Port and Starboard
Two boats heading toward each other on opposite tacks. Who has to move?
The situation
Two boats are heading toward each other on opposite tacks. One is coming from your left, one from your right. Both skippers are pretty sure they have right of way. Both keep going. Somebody is wrong.
This is the most common argument in club racing. It happens upwind, downwind, on reaches, on the start line, and at every windward mark approach. If you race, this situation finds you every weekend.
The rule, in plain English
The boat with the wind on her starboard (right) side has right of way. The boat with the wind on her port (left) side has to keep clear. That's it. The starboard tack boat does not have to do anything except hold her course. The port tack boat has to do whatever it takes — tack, bear away, slow down — to avoid contact.
Common questions
Who has right of way when two sailboats are on opposite tacks?
The starboard tack boat. The port tack boat must keep clear under Rule 10.
How do I know which tack I'm on?
Look at the boom. Boom on the port (left) side = you're on starboard tack. Boom on the starboard (right) side = you're on port tack. The tack is named for the side the wind is coming from, not the side the boom is on.
What if both boats think they have right of way?
Only one of them actually does — the starboard tack boat. If both keep going there will be contact and the port tack boat is in the wrong under Rule 10. The starboard boat can also be penalised under Rule 14 if she did nothing to avoid contact once it became obvious the port boat wasn't going to keep clear.
Does it matter if the starboard boat changes course?
Yes. Rule 16.1 says when the right of way boat changes course she must give the other boat room to keep clear. If starboard luffs hard or bears away suddenly and port can no longer avoid her, starboard breaks Rule 16.1 even though she had right of way under Rule 10.
What if I'm on port and I tack to avoid the collision?
Tacking is a legitimate way to keep clear. But under Rule 13, while you are tacking you have no rights — you must complete your tack to a close hauled course before any other boat is required to keep clear of you. So pick your moment.
What if I didn't see the starboard boat in time?
You've still broken Rule 10. Lookout is your responsibility. Standard penalty is a two-turns penalty, or retirement plus damages if there was contact.
Does Rule 10 apply downwind too?
Yes. Rule 10 applies whenever the two boats are on opposite tacks — upwind, downwind, or reaching. Tack is decided by which side the wind is on, not by where you're heading.
What about at a mark?
Rule 10 applies right up until a boat reaches the zone — three boat lengths from the mark. Inside the zone, Rule 18 (mark room) takes over. That's a different argument and a different page.
📚 Want to go deeper?
- The Racing Rules of Sailing 2025–2028 (Official World Sailing Rulebook)
- Understanding the Racing Rules of Sailing — Dave Perry
- Paul Elvstrøm Explains the Racing Rules of Sailing
- 100 Best Racing Rules Quizzes — Dave Perry
As an Amazon Associate I earn from qualifying purchases. Links above are affiliate links — your price doesn't change.
Argue this one with the rest of us
Join the Sailing Kiwi Facebook group — sailors from clubs across NZ and beyond, swapping rule situations every week.
Join the Facebook group →Related rules
- Rule 11 — Same tack, overlapped (windward keeps clear). Coming soon.
- Rule 13 — While tacking. Coming soon.
- Rule 14 — Avoiding contact. Coming soon.
- Rule 18 — Mark room. Coming soon.