CALL F3 Rule 17
On the Same Tack; Proper Course
Question A and X are reaching, both above their proper courses, with X just clear ahead and one length to windward of A. X bears away so that the boats become overlapped. A promptly bears away to a proper course. X protests. What should the call be?
X1 X2
X3 A1
A2 A3
Proper course to next mark
Answer Rule 17 begins to apply when the boats become overlapped. From that moment on, A must sail no higher than her proper course from the position she is in when the overlap begins (position 2) - i.e., she must sail no higher than a course that she would sail in the absence of X from position 2 to reach the next mark as quickly as possible. By bearing away promptly, A complies with this rule. No penalty. The answer is the same if the overlap is established through A sailing faster rather than X bearing away. A boat has no obligation to be on a proper course in anticipation of a proper course requirement that does not yet exist. A new requirement to sail a proper course applies from that time and from the position the boat is then in.