Proper Course

Originally posted by Brass The external wave would have come along whether the windward boat (that must have been there to get us into rule 17 territory in the first place) was there or not:  the change in conditions would have occurred in the absence of the windward boat, responding to the wave would be leeward's proper course.

Since waves have been brought into the discussion.

In the same context of apparent wind changes due to the windward boat, I would assume the same logic would also be applied to a change in sea state caused by the windward boat (i.e stern and bow wave)? This could be relevant in semi-planing/surfing conditions.

I really feel that we are making life too complicated. A boat, as far as the rules are concerned is a sailboat and her crew. I can find no reference in the rules to a boat including windshadow, bow wave, stern wave or whatever.

If there are no cases on a rule that is usually because there are few, if any, protests involving that rule.

In this case, if the leeward boat was that close to the windward boat I would be looking more at rule 16.1 than 17.

Windward boat is required to keep clear (even if rule 17 is on) and leeward boat is required to give room to keep clear if she changes course.

If windward could not keep clear while manoeuvering in a seamanike way then leeward has broken rule 16.1. If she can  keep clear all well and good and there is unlikely to be an incident to protest.