Overrides the right-of-way rules of Section A while it applies.
Three situations where a boat that would otherwise have right of way loses it because she is doing something unusual.
21.1
After the starting signal, a boat sailing back towards the pre-start side of the line or its extensions to start (or to comply with the I flag rule, rule 30.1) keeps clear of boats that are not, until her hull is completely on the pre-start side. Once she is back she gets her normal rights, subject to rule 15.
21.2
A boat doing penalty turns keeps clear of every boat that is not. The obligation starts when she begins the turns, so get well clear first.
21.3
A boat moving astern, or sideways to windward, through the water by backing a sail keeps clear of boats that are not. This is the common pre-start case of a boat pushing her boom out to back down.