America's Cup organisers have made a late rule change to cover off serious damage circumstances like Team New Zealand incurred in practice racing.

With the syndicates only having one boat, there have been concerns among the teams about the costly consequences of having their highly technical catamarans unexpectedly sidelined.

Last week Team New Zealand spent four days doing repairs after being rammed by Britain's Sir Ben Ainslie who would have been able to race the next day.

Cup bosses have now covered off this situation with a last-minute tweak of the rules to provide some redress for the innocent party.

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In a nutshell, a team has 24 hours to fix their boat or it's tough luck.

There are three key areas to the technical changes.

The first sees the affected team having to prove they could not avoid the contact from either a rival boat, a spectator boat or a race official's boat.

If that is proved the damaged team will get the point for the race.

Officials can also delay that team's other races on that day through to the following day.

The third tweak allows a damaged boat a 24-hour grace period to undergo repairs. If that can't be achieved, the syndicate will lose any points for the second and subsequent days lost failing to make the start lines.

Basically, if the Team New Zealand situation had happened during actual racing, they would have got the point for the race. The British would have lost that point but could have done quick repairs to see out the rest of their racing schedule on that day and subsequent days. Team New Zealand would have been given a 24-hour period to fix the boat but they would have lost any points they might have picked up over the next three days.

In undertaking their repairs last week the Kiwis emphasised that they would have been able to do a quick patch-up job that would have allowed them to be back on the water in 24 hours. With no racing pressure on, they took their time to make an elaborate repair and also tweak other areas of the boat.

Interestingly the delays can't affect the next phase of the regatta which has a tight deadline to squeeze in the double round-robin qualifying series, the challenger semifinals and final and the actual America's Cup final. The heat is being applied to the shore crews to get work done quickly.

And the third part of the rule doesn't apply to Oracle if they take up their chance of having a second boat as they are allowed under the rules being the defender. They would have to use that second boat.

Official Cup racing starts on Sunday after being delayed by high winds for a day.

Team New Zealand are set to face Team France and defenders Oracle in their first two races.