Here is another Mark round situation
Situation:
Blue and Red boat are approaching the Leeward offset Mark. Blue boat reached the zone clear ahead of Red boat. Rule 12 (ON THE SAME TACK, NOT OVERLAPPED) applies as does Rule 18.2b (Giving Mark-Room).
12 ON THE SAME TACK, NOT OVERLAPPED
When boats are on the same tack and not overlapped, a boat clear astern shall keep clear of a boat clear ahead.
18.2b Giving Mark-Room
(b) If boats are overlapped when the first of them reaches the zone, the outside boat at that moment shall thereafter give the inside boat mark-room. If a boat is clear ahead when she reaches the zone, the boat clear astern at that moment shall thereafter give her mark-room.
Remember the definition of Mark-Room. The 2nd sentence of Rule 18.2b requires the boat clear astern at that moment to give the ROW Blue boat Mark-Room. The 1st sentence of the definition of Mark-Room requires the Red clear astern boat to allow the Blue boat to sail to the Mark and , and then room to sail her proper course while at the mark. The 2nd sentence also does not include room to tack as part of Mark-Room for the Blue ROW boat as she is not overlapped with the Red boat. The Red boat must provide Mark-Room for the clear ahead Blue boat. As the Blue boat sails toward the mark, his options are to sail to the mark and tack around the mark or to pass the mark on port tack until she can tack without breaking Rule 13 (WHILE TACKING) Remember that the Blue boat does not have a right to tack at the mark, but she may if she complies with Rule 13.
Blue ROW boat decided to not use the Mark-Room provided at the Mark and sailed pass the mark on Port tack.
Once a perpendicular line from the stern of Blue has passed the mark, Mark-Room is turned off and only Rule 12 applies. The clear astern Red boat must stay clear of Blue boat.
After the Blue boat has passed the mark, she decided that she would tack onto starboard and beat to windward. Remember Mark-Room does not include the right to tack in this situation, but she can luff to close-hauled course.
Once the Blue boat passes Head-To-Wind, Rule 13 now applies. Blue boat must stay clear of the Red boat that is still on a tack. Once Blue boat passes Head-To-Wind, Red boat becomes the ROW boat and Blue boat must stay clear of Red boat. Blue boat’s tack was assisted with wind and she passed Head-To-Wind quickly and failed to stay clear of Red boat, breaking Rule 13. Even though Blue was now on Starboard, Rule 15 applied to Blue boat. Red boat was not obligated to anticipate Blue boats tack and because of the speed of the tack, Red boat was unable to avoid contact with Blue boat. Red boat protested Blue boat for breaking Rule 13 and 15 while Blue boat protested Red boat for breaking rule 10 and 14 Avoiding contact. There was no damage caused by the contact.
Blue boat violated Rule 13 (Tacking too close) and Rule 15 (Acquiring the ROW), Red boat violated Rule 14 but will be exonerated because Red boat was the ROW at the time of contact and there was no damage. Rule 10 did not apply to the Red because Rule 13 was in effect at the time of the contact.
15 ACQUIRING RIGHT OF WAY
When a boat acquires right of way, she shall initially give the other boat room to keep clear, unless she acquires right of way because of the other boat’s actions.
10 ON OPPOSITE TACKS
When boats are on opposite tacks, a port-tack boat shall keep clear of a starboard-tack boat.
If Blue boat has increased the clearance ahead of Red boat prior to tacking, she would have conpleted her tact and be sailing on a close hauled course which would have required Red boat to stay clear (Rule 10).