KEY POINTS:
With little expected to separate the teams in this America's Cup the umpires may come under huge pressure. The umpires determine if any of the rules have been broken - and respond to protest calls from either of the competing yachts.
They can impose a penalty on an
infringing boat, which requires a turn of at least 270 degrees to clear oneself. This turn often represents a loss of more than 30 seconds therefore can alter the outcome of a race.
The umpires' decisions on the water are instant, there are no stoppages. Unlike other sports, in the America's Cup the game keeps rolling.
During a race the big action for umpires is at the pre-start, during upwind crosses, downwind and at the marks. There is an umpire boat, which has a driver and two umpires on board and a wing boat which also has a driver and two umpires.
The umpires on each boat take one race yacht each and communicate like they are sailing on that race boat. For example if they are the starboard boat [coming in from the committee boat end] on the entry into the startbox they would say "I have entered. I am the right-of-way boat and the other boat must keep clear".
The other umpire would be saying "I have entered I am the port boat I must keep clear".
They talk it through like a tactician would.
If there is an incident the umpires have to agree. Let's say there is a classic port/starboard incident. The starboard tack boat is the right-of-way boat. The port tack boat is the must-keep-clear boat but they fail to do so.
That would mean the starboard tack umpire would be going "I am the right-of-way boat I am holding my course."
The umpire of the port tack boat would be saying "I must keep clear". Then there is an incident "I failed to keep clear".
They would both agree and penalise that boat. If they disagree they would green flag it.
On the race boats teams can hoist a yellow and red diagonally-striped protest flag requesting the umpires penalise the other boat following what they consider to be a breach of the right of way rules. The umpires use flags to communicate with the teams.
* A green and white flag means no penalty.
* A blue or yellow flag means the identified boat shall take a penalty. The yellow flag is flown by the boat which entered the pre-start on the right and a blue flag by the boat that entered on the left.
* A red flag flown together with a blue or yellow flag means that boat shall take its penalty immediately.
* A black flag with a blue or yellow flag means the identified boat has been disqualified.
If a boat gets a third penalty it cops a black flag. Teams can get penalised for not keeping clear when they are the give way boat, if there is a collision etc. If you get a penalty it can be cancelled out if your opponent also gets penalised.
Team cannot protest against the umpires' decisions. They can only seek redress on incidents which are not their fault such as if the race committee makes a mistake or a spectator boat gets in the way or if there is a prang.
A new innovation in this cup is that the umpires now control a lighting system on the race boats. If there is an overlap it will set off a light in front of the helmsman.
The umpires will play an integral part in this America's Cup. With the racing expected to be close they are going to come under increased scrutiny and pressure. I for one am expecting to see some fireworks off the coast of Valencia.