Question 1
Prior to the start, Yellow, on starboard, and Blue, on port, are sailing more than ninety degrees from the true wind. Both boats are sailing towards an obstruction. At position 3, Yellow luffs to avoid Blue and displays a Y flag.

What should the call be?

Answer 1
Penalize Blue.

Yellow is the right of way boat and the umpires are certain that Yellow has chosen to pass the obstruction on her port side (rule 19.2(a)).

For the purpose of rule 19, the determination of inside and outside boat is relative to the right of way boat and the obstruction when the boats are at the obstruction. As Yellow is passing the obstruction on her port side, any boat that is on the port side of Yellow is an inside boat and any boat on the starboard side of Yellow is an outside boat.

At position 2 Blue is the keep clear boat that also has to give Yellow room at the obstruction. Yellow changes course from positions 1 to 2 and Blue has room to keep clear. After position 2, Blue fails to keep clear and give Yellow room to pass the obstruction.

Question 2
Would the answer be different if Blue was sailing parallel and close to the obstruction?

Answer 2
No.

Question 3
Prior to the start, Yellow, on starboard, and Blue, on port, are sailing more than ninety degrees from the true wind and both boats are sailing towards an obstruction. Yellow is on a course that the umpires cannot be certain as to the side Yellow will pass the obstruction. Blue changes course to starboard and Y flags.

Answer 3
Display the green and white flag.

Rule 19.2(b) applies when two boats are at an obstruction. In order to determine the inside and outside boat, the umpires need to be certain what side of the obstruction the right of way boat chooses to pass.

At position 2, the right-of-way boat is sailing perpendicular to the obstruction. Therefore, it is not possible to clearly identify which boat is the “inside” boat. When the umpires are not certain which boat is the “inside boat,” no part of rule 19 creates any obligations, and rule 11 requires Blue to keep clear.