So, while no rule requires you to anticipate, common sense (and good seamanship, as Mark mentions) requires you to do so.
Actually, RRS 18.2(e) implicitly requires an outside boat to anticipate the mark-room needs of an inside boat. That, however, is a different discussion.
Conversely, there is no rule that says you do not have to anticipate.
Perhaps we're getting bogged down in the semantics of the word "anticipate". Of course, one should attempt to forsee upcoming encounters and plan ahead. Rule 14(a), however, makes it quite clear that "...a right-of-way boat or one entitiled to room or mark-room need not act to avoid contact until it is clear that the other boat is not keeping clear or giving room or mark-room...". ISAF Case 27 also explicitly states "a boat is not required to anticipate that another boat will break a rule".
In fact, ISAF Case 27 is a very close match to what happened between Artemis and Groupe Edmond. I encourage everyone here to look it up. It involves a port-tack boat that tacked onto starboard inside the zone in front of an oncoming port-tack boat. The only difference is that Groupe Edmond tried to avoid contact but the boat in the case did not. The case concludes "...while it was obvious that AS would have to tack to round the mark, BP was under no obligation to anticipate that AS would break rule 15, or indeed any other rule".
I think people have a tendency to replace the words "act to avoid contact" with "anticipate" which is really bad in practice.
I agree. Let's talk in terms of "act" and "react". When, for example, a right-of-way boat changes course (acts), a keep-clear boat must react promptly, and in a seamanlike way. The keep-clear boat is not required to react before the right-of-way boat acts, regardless of what she may anticipate.
Regards,
Eric
