so, since I can't find my rule book.... when is a tack completed?

So... in the rules :
13 WHILE TACKING
After a boat passes head to wind, she shall keep clear of other boats
until she is on a close-hauled course.

The boat that tacked in front of me can get to a close hauled course (and not be moving at all?) and then I would still have to avoid them?

I bring this up to discuss it and learn from it and because I value some people's opinions. I do read the rules.