We have US Appeal 15 which provides guidance US Appeal 15
.. and like US15, I'm interested in discussing when it's OK to call for room to tack.
Since we are already non-dimensionalizing the question based upon the length of the boat in question ... it seems to me this comes down to an angle.
What has it been in practice for you in your hearings? 5 deg? 10 deg? 30 deg? more? .. less?
In practice, in an OD fleet in crossing situations to windward, a leeward boat on port with a port boat to windward and on a bow-to-bow collision course with a starboard tack boat, is the course to duck in an OD fleet "substantial"?
What if the course was a mid-boat collision point on the starboard-boat?
I think it's easier to think about this when all the boats are the same size as it takes the boat's dimensions out of it.
PS .. let's assume the boats are all moving at the same speed for the sake of discussion.