Rule 10

On Opposite Tacks

Rule 10 - ON OPPOSITE TACKS

When boats are on opposite tacks, a port-tack boat shall keep clear of a starboard-tack boat.

Relevant Definitions

Keep Clear

A boat keeps clear of a right-of-way boat

(a) if the right-of-way boat can sail her course with no need to take avoiding action and,

(b) when the boats are overlapped, if the right-of-way boat can also change course in both directions without immediately making contact.

Tack, Starboard or Port

A boat is on the tack, starboard or port, corresponding to her windward side.

Leeward and Windward

A boat’s leeward side is the side that is or, when she is head to wind, was away from the wind.

However, when sailing by the lee or directly downwind, her leeward side is the side on which her mainsail lies. The other side is her windward side.

When two boats on the same tack overlap, the one on the leeward side of the other is the leeward boat. The other is the windward boat.

Examples: Port (blue) must keep clear of Starboard (yellow)

Beating to windward

Yellow (on Starboard) approaching Blue on the beat.

Options for Blue (on Port):

  • Keep clear by tacking away from Yellow
  • Keep clear by ducking behind Yellow

On the run

Yellow (on Starboard) approaching Blue on the run.

Options for Blue (on Port):

  • Keep clear by ducking behind Yellow (shown)
  • Keep clear by Gybing away from Yellow

Yellow (on Starboard) approaching Blue from clear astern.

Options for Blue (on Port):

  • Keep clear by getting out of the way(shown)
  • Gybe onto Starboard, so that the two boats are no longer on opposite tacks. With both boats on the same tack, it becomes a Rule 12 scenario.

Reaching

Yellow (on Starboard) approaching Blue on a reach.

Options for Blue (on Port):

  • Keep clear by ducking below (shown)
  • Keep clear by going above