Fact Finding for a Finish Foul

Received an Email from a new LTW- reader this week asking about a situation he experienced during an evening training event:

Approaching the finishing line yesterday evening, and unable to make the buoy I luffed almost head to wind and sneaked round. The boat to windward [but not ahead] had to luff to avoid me and I got my bow over the line before his.

He said later that if we hadn't been training he would have protested as I wasn't sailing my proper course, he could make the mark so I should have dropped off and tacked behind him to finish. I suggested that for me this was the route I would have taken if he hadn't been there and as I hadn't passed through head to wind he had to keep clear.

We're still the best of friends but it would be nice to clear the situation up - it's bound to crop up again sooner or later.

I answered in a mail:

As to your question. Firstly, you have a proper course restriction only of the overlap was established from clear behind within two boat lengths to leeward of your friends boat. If you got the overlap any other way you have no restriction and may luff head to wind as you please, provided you give him room to keep clear.

If there was a proper course restriction under rule 17.1, you are still allowed to luff head to wind in this situation. For you that was the fastest way to finish. Like you said, you would have done the same if the other boat wasn't there.

You could even have just crossed the line with your bow and then gone back. There's no need to cross the finish line with the whole boat.

Later I realized I maybe was to quick with my answer. Oh, it is not wrong, but because Andrew never told me what happened before that situation, there is a possibility he did break a rule.

I've drawn up the following diagram to illustrate:

In this situation Blue and Yellow approach on opposite tacks and then Blue completes his tack within the two-length zone. Yellow has to sail above close hauled to avoid her, therefore Blue breaks rule 18.3(a).

This illustrates that you need to find out ALL the facts before jumping to a conclusion. Perhaps there are more ways Blue can end up in this situation and break a rule?