I'll give you some more data

1) the wind speed was approximently 8 knots

2) the windward (W) boat was a A-cat moving downwind at approximently 8 knots

3) the leeward (L) boat was a TheMightyHobie18 closehauled/single trapped moving at 5-6 knots

4) (L) attempted to hail (W) twice w/ no responce from (W).

5) At the point that (L) calculated that they were with-in 4seconds of a collision with (W)looking straight ahead laying out flat ignoring all hails (L) headed up sharply (approximently 40degrees), luffing their jib and slowing significantly, coming almost head to wind but still had approximently 1knot of boatspeed ... (W) at this point passed across (L)'s bows at approximently 10'... (L) was then able to "foot off" and start to re-accerlerate (of course the crew was "teabagged")
6) (W) never looked back ... or did a penalty circle ...

In (L)'s opiniun they felt that they had waited to the last reasonable moment to take evasive action .... (W) obviously thought they would clear.

So how close is too close and who gets to determine that ... (L) who is an experienced sailer w/ a 13yr old as crew or (W) who is a experienced sailor also but very aggresive.

Harry