The match begins with a horn signal at 7 minutes before the start is given. The horn sounds again at 5 minutes before the start and at 4 minutes together with the hoisting of a blue and white flag on the starting boat. In the following two minutes both boats, one with a yellow, the other with a blue flag on its stern, sail from opposite sides over the starting line into the starting area.
At this point, until the starting signal, the first part of a duel begins. As soon as the boats enter the starting area they will engage in a pre-start battle as each one tries to gain an advantage over the other. They will both be trying to cause the other boat to infringe a rule and so receive a penalty or to simply get the most advantageous position on the starting line for themselves so they are in control of the race. One trick, using sailing's "right of way" rules, is to force the opponent into an early start, meaning the boat has to return back behind the starting line.
There are two basic "right of way" rules in match races; 1)the boat with wind from the right (starboard) has right of way, the opposing boat has to keep clear, and 2) in a double length circle distance from turning buoy, the boat on the inside has right of way and can turn first. The duels usually happen in the narrowest space. Wins and losses are often decided by only a boat length.
Match racing is officiated by umpires on the water who follow the boats and make instant on-course decisions about whether a penalty is given. A boat which receives a penalty has to do a penalty turn (270 degree turn). This penalty turn must, unless otherwise signaled, take place at the latest, before entering the finishing line. If one boat has a penalty and the other boat also gets one before the first has taken their penalty turn, then they are cancelled out. If a boat receives three penalties then it is disqualified.
Every match is watched and followed by two judges in small power boats who, depending on the incident, make decisions on protests and give penalties. When one of the two teams protests by raising a yellow/red striped flag, the judges will respond by raising one of the following 5 flags:
Blue - The boat with the blue flag must do a penalty turn
Yellow - The boat with the yellow flag must do a penalty turn
Green - There are no grounds for protest
Red - The boat affected must immediately do a penalty turn
Black - The boat affected is immediately disqualified from the race