Hi all,

I’m looking for clarification on how Rule 17 applies in the following situation.
Boat Y is at the start line on starboard tack.
Boat X, initially clear astern, becomes overlapped to leeward within two hull lengths of Boat Y while both are on starboard, before the starting signal.
The starting signal sounds, and the boats remain overlapped as described above.

Questions
1 Is Rule 17 “on” before the start, but effectively inactive because there is no proper course before the starting signal?
2 After the start, does Rule 17 apply even though the overlap was established before the start? In other words, once the race has started, must Boat X (the leeward boat) not sail above her proper course while the overlap continues?
3 How long would Rule 17 continue to apply?

My current thinking
1  = Rule 17 is technically in effect before the start, but has no practical effect because there is no proper course before the starting signal.
2 = After the start, Rule 17 still applies, even though the overlap was created before the start, meaning Boat X cannot sail above her proper course while overlapped.
3 = Rule 17 would continue to apply until the overlap is broken, the boats separate by more than two hull lengths, or one of the boats tacks.

Additional thought
Since Boat X is the leeward boat, her proper course could still be higher than Boat Y’s current course, meaning she might still be able to luff enough to force Boat Y to tack without breaking Rule 17, provided she does not sail above her own proper course.

Your thoughts are welcome.

Thanks,
Nick