The important thing is for the sailors to look ahead and take action before they run out of water. Imagine Boat A is sailing close-hauled on starboard tack, approaching an obstruction that is not a mark, and that will require her to tack to pass it safely. She looks around and sees Boats B, C, and D, all astern and to windward. A realizes that she cannot tack and avoid Boat B. She can probably tack and cross Boat C, but given the shifty wind conditions, is not sure. A is confident that she can avoid Boat D. A then should hail both B and C individually, for room to tack (RRS 20.1).

Boat B then looks around, decides she needs to tack but realizes that she cannot tack and avoid Boat E, who is on B's weather hip. Boat B passes along the hail by requesting room to tack from Boat E (RRS 20.3).

Boat C decides she can continue straight, and alter course if necessary to give A room to avoid her. C responds to A's hail by replying "You tack" (RRS 20.2(c), second clause).

Boat E looks around, decides she needs to tack, and fortunately there is no boat preventing her from doing so. E responds to B's hail by tacking as soon as possible (RRS 20.2(c), first clause).

When E tacks, B must tack as soon as possible (RRS 20.2(c) and 20.2(d)).

When B tacks, A must tack as soon as possible (RRS 20.2(d)). Boat C must then give A room to tack and avoid her (RRS 20.2(c)).

To avoid incident, all this must play out before Boat A reaches the obstruction. Therefore, it is vitally important that she assess her situation and evaluate her needs and risks well before she has to maneuver. Not only must Boat A act herself, but she must hail early enough to give other boats time to act as well.

In the scenerio described, Boat 1 did not anticipate her needs well enough in advance, did not hail Boat 3 for necessary room, and consequently sailed into an untenable position. She had to make emergency maneuvers that cost her the race. Boat 2 did not protect herself by passing the hail on to Boat 3. As a result, she had to take a risky duck and wound up fouling Boat 3. Boat 2 should have taken a penalty. Boat 3 fulfilled her obligations under the rules. Because no boat hailed her for room, she was not required to give it. She acted to avoid contact as required by rule 14. She would have been entirely within her rights to protest Boat 2. Fortunately for Boat 3, her position in the race was not adversely affected.

I hope that helps,
Eric