Rule 17 On the same Tack; Proper Course
Rule 18.1 When Rule 18 Applies
Rule 18.4 Gybing
Definitions Proper Course
Question 1
Yellow and Blue enter the zone of the leeward mark overlapped with Blue as the
inside right-of-way boat. Rule 17 does not apply, however, as proper course
at the mark includes a gybe, rule 18.4 applies to Blue.
Because of strong current and light wind, Blue’s proper course would take
her outside the zone before she gybes and heads back to the mark. When Blue
reaches the point where her proper course is to gybe, both boats are outside
the zone.
Is Blue still required by rule 18.4 to gybe at that moment? (Position 3)
Answer 1
No. When both boats have left the zone rule 18, including rule 18.4, no longer
applies and therefore Blue is no longer required by rule 18.4 to gybe.
Question 2
Would the answer be the same if rule 17 applied to Blue?
Answer 2
No, rule 17 is not dependant on whether or not rule 18 applies. When rule 17
applies it requires Blue to not sail above her proper course, so in this situation
she must gybe when her proper course is to gybe even though both boats are outside
the zone.