Before the start, and before approaching any starting mark to start, Yellow and Blue approach a large moored boat with Yellow half a length ahead. It appears that Blue intends to pass across the stern of the large boat, and that Yellow requires room to pass on the same side on the inside of Blue. Blue does not bear away to give room, and at the last moment Yellow avoids the large boat by luffing sharply and going to windward of it. Before the bow of Blue reaches the stern of the large boat, she gybes away so that she does not pass its stern. There is a Y-flag. What should the call be?

Penalize Blue. The large boat was an obstruction. Unless Blue elects to pass to windward of it from sufficiently far away, Yellow may assume that they are both going to bear away below the obstruction. It follows that Blue must give room. By not doing so, she broke rule 19.2(b).