L, M and W are sailing close-hauled on starboard tack. They are approaching an obstruction that L cannot safely avoid without making a substantial course change. The obstruction is not a mark. When the boats are in the positions shown in the diagram, L hails 'Room to tack' loudly enough to be heard by both M and W. When L hails, it is clear that M and W must both tack in order to give room to L, and M does not have room to tack and avoid W.

Does rule 20.2(c) require W to respond to L's hail?

Yes. When a boat that is not adjacent to the hailing boat has heard the hail, and will have to respond before the hailing boat is able to tack, she is a "hailed boat" in the context of rule 20.2 and she shall respond accordingly.

Is M required to hail W for room to tack immediately after L's hail?

Yes, if W is not already responding to L's hail. Because replying "You tack" is not an option for M in this case, M is required by rule 20.2(c) to respond to L's hail by tacking as soon as possible. Therefore, if M cannot tack because of the presence of W, she must immediately hail 'Room to tack' to W, and rule 20.3 permits her to do so even if, in the absence of L, M would not yet need to hail 'Room to tack'. If M fails to hail for room, and as a result is unable to tack as soon as possible, she breaks rule 20.2(c).

World Sailing 2009