The meanings of the visual and sound signals stated in Race Signals shall not be changed except under rule 86.1(b).  The meanings of any other signals that may be used shall be stated in the sailing instructions.

When the race committee is required to display a flag as a visual signal, it may use a flag or other object of a similar appearance.

Races shall be started by using the following signals. Times shall be taken from the visual signals; the absence of a sound signal shall be disregarded.

  Minutes before                Visual Signal                        Sound             Means
   starting signal                                                              Signal

           5*                             Class flag                                One               Warning signal
           4                 P, I, Z, Z with I, U, or black flag           One               Preparatory signal
           1                   Preparatory flag removed               One long           One minute
           0                        Class flag removed                       One                Starting signal
 * or as stated in the sailing instructions

The warning signal for each succeeding class shall be made with or after the starting signal of the preceding class.

No later than the warning signal, the race committee shall signal or otherwise designate the course to be sailed if the sailing instructions have not stated the course, and it may replace one course signal with another and signal that wearing personal flotation devices is required (display flag Y with one sound).

A boat shall start, sail the course described in the sailing instructions and finish. While doing so, she may leave on either side a mark that does not begin, bound or end the leg she is sailing. After finishing she need not cross the finishing line completely.

A string representing a boat's track from the time she begins to approach the starting line from its pre-start side to start until she finishes shall, when drawn taut,

When at a boat's starting signal any part of her hull, crew or equipment is on the course side of the starting line or she must comply with rule 30.1, the race committee shall promptly display flag X with one sound.  The flag shall be displayed until all such boats have sailed completely to the pre-start side of the of the starting line or one of its extensions and have complied with rule 30.1 if it applies, but no later than four minutes after the starting signal or one minute before any later starting signal, whichever is earlier. If rule 30.3 or 30.4 applies this rule does not.
 

If flag I has been displayed, and any part of a boat's hull, crew or equipment is on the course side of the starting line or one of its extensions during the last minute before her starting signal, she shall sail across an extension to the pre-start side before starting.

If flag Z has been displayed, no part of a boat’s hull, crew or equipment shall be in the triangle formed by the ends of the starting line and the first mark during the last minute before her starting signal. If a boat breaks this rule and is identified, she shall receive, without a hearing, a 20% Scoring Penalty calculated as stated in rule 44.3(c). She shall be penalized even if the race is restarted or re-sailed, but not if it is postponed or abandoned before the starting signal. If she is similarly identified during a subsequent attempt to start the same race, she shall receive an additional 20% Scoring Penalty.

If flag U has been displayed, no part of a boat’s hull, crew or equipment shall be in the triangle formed by the ends of the starting line and the first mark during the last minute before her starting signal. If a boat breaks this rule and is identified, she shall be disqualified without a hearing, but not if the race is restarted or resailed.

If a black flag has been displayed, no part of a boat’s hull, crew or equipment shall be in the triangle formed by the ends of the starting line and the first mark during the last minute before her starting signal. If a boat breaks this rule and is identified, she shall be disqualified without a hearing, even if the race is restarted or resailed, but not if it is postponed or abandoned before the starting signal. If a general recall is signaled or the race is abandoned after the starting signal, the race committee shall display her sail number before the next warning signal for that race, and if the race is restarted or resailed she shall not sail in it. If she does so, her disqualification shall not be excluded in calculating her series score.

While racing, a boat shall not touch a starting mark before starting, a mark that begins, bounds or ends the leg of the course on which she is sailing, or a finishing mark after finishing.
 

After the starting signal, the race committee may shorten the course (display flag S with two sounds) or abandon the race (display flag N, N over H, or N over A, with three sounds),

In addition, the race committee may shorten the course so that other scheduled races can be sailed, or abandon the race because of an error in the starting procedure. However, after one boat has sailed the course and finished within the time limit, if any, the race committee shall not abandon the race without considering the consequences for all boats in the race or series.

If the race committee signals a shortened course (displays flag S with two sounds), the finishing line shall be,

The shortened course shall be signaled before the first boat crosses the finishing line.

The race committee may change a leg of the course that begins at a rounding mark or at a gate by changing the position of the next mark (or the finishing line) and signalling all boats before they begin the leg. The next mark need not be in position at that time.

If a mark is missing or out of position, the race committee shall, if possible,

If one boat sails the course as required by rule 28 and finishes within the time limit, if any, all boats that finish shall be scored according to their finishing places unless the race is abandoned. If no boat finishes within the time limit, the race committee shall abandon the race.

If a race is restarted or re-sailed, a breach of a rule in the original race, or in any previous restart or re-sail of that race shall not