Crowding the stern
The situation
Same tack upwind, Ada is just clear ahead of a faster boat coming up from astern. The astern boat noses right up close behind and starts to slide alongside to leeward.
The question
When does the boat astern actually get rights — and what must she do until then?
The ruling
Until an overlap truly exists, the boat clear astern keeps clear of the boat clear ahead (rule 12). Getting close gives her nothing; she must steer around. The instant she establishes a leeward overlap, right of way switches under rule 11 — but rule 15 then makes her give Ada room to keep clear, and if the overlap came from clear astern within two hull lengths, rule 17 caps her at proper course. Crowding the stern hoping an overlap 'just happens' is exactly how fouls happen.
Clear astern keeps clear until a real overlap forms — sailing up close earns you no rights (rule 12).
Opens the situation on the boat-length grid — scrub it and see exactly how the boats meet. Free, no account needed.
Rules cited
- Rule 12 — On the Same Tack, Not Overlapped
- Rule 11 — On the Same Tack, Overlapped
- Rule 15 — Acquiring Right of Way
See the underlying rule: Rule 12 — On the Same Tack, Not Overlapped.
Related cases
- The lee-bow tack · Upwind / Beating
Crossing on port, Tom decides to tack onto starboard right on the lee bow of an oncoming starboard-tack boat, hoping to slow her and roll over the top. He tacks close ahead and to leeward.
- Two Optis tack at once · Upwind / Beating
On a big shift, two boats near each other both tack onto the new tack at the same moment. As they come out of their tacks close together, who had to keep clear?
- Defending your lane · Upwind / Beating
A boat is creeping up to windward, trying to roll over Priya. Priya, the leeward boat, luffs gently to slow the windward boat and protect her wind.
- Port meets starboard on the beat · Upwind / Beating
Both boats are beating to windward and their courses cross. Green has the wind on its starboard side; Red has it on the port side.