I have two questions: 1) How far away from traffic should you be so you can change course without violating your responsibility as stand-on vessel? 2) If the give-way vessel does not change course how close do you let things get before you take action?
As an example I sometimes sail through an area that has two ferries running the same route. I like to stay out of their way, so basically as soon as I see one I change course so that I'll run well behind it. If they're both out and running behind one would put me in front of the other I'll change course to run parallel to them until they're about to pass, then turn back so I'll pass behind both of them.
I'm assuming this is cool because they're at the point where I can't really even see the cars on deck, so I figure I'm not obligated to stand-on yet.
On the other hand let's say that I wasn't paying attention or there was fog or something and I realize I'm getting close, like I can see people on deck, and we're on a collision course. At this point I'm obligated to stand on, right? How long do you stand-on before you do a panic tack to get out of the way? Whites of their eyes?
I think Rule 17 gives about as much guidance as can be given in a situation where you wonder if give-way sees you, or even knows what to do.
(a)(ii) says that stand-on "may, however, take action to avoid collision byher maneuver alone, as soon as it becomes apparent to her that give-way is not taking appropriate action in compliance with these rules"
and (b) says, essentially, "When stand-on finds herself so close that collision cannot be avoided by the action of give-way alone, she shall take such action as well best aid to avoid collision".
while (c) says, "you shall, if circumstances of the case admit, not turn port towards a vessel on your own port side"
So, you "May" take action if the other boat isn't taking appropriate action, and you "must" take whatever action as best avoids collision once give-way is so close that he couldnt avoid it on his own..
Just don't turn to port into him, if you can help it.
The trick is in determining just when give-way isn't taking appropriate action, and then when he can't avoid collision by himself anymore. Good sailors may differ on this in the same given situation.
That's why, "when there's a collision at sea, there are many wise men on shore" ;-)