The America's Cup sailing has been damned as unfair and unsafe so far, with a leading challenger telling an official hearing that "serious failures" put the event in jeopardy.
With the Prada Cup racing to begin on Friday, the New York Yacht Club says it holds "serious concerns" about the regatta which will culminate in Team New Zealand's defence of the Auld Mug in March.
The American Magic challenge, skippered by Kiwi Dean Barker, indicated to an AC arbitration panel that the problems experienced in pre-Christmas racing suggested the main event faced major trouble unless solutions were found.
The four teams involved went through their paces in December's World Series.
The claims are detailed in the arbitration panel's ruling over a dispute concerning practice racing this week, a typically convoluted America's Cup argument where the defender and challengers often seek to gain advantages or not lose ground.
American Magic told the hearing: "The Race Management System is a complex electronic system supplied and provided by the organisers and it includes the Media System on board each AC75.
"For the crew to see the on-board instrument data while racing, such data must first pass through the Media System and from there to the displays and screens of the AC75.
"Furthermore, all racecourse information and all umpire calls are managed and received by a competing AC75 in the Race Management System.
"In short, with the failure of the Race Management System, no fair racing is possible.
"All competitors (during the pre-Christmas sailing) have experienced serious failures... which fundamentally curtailed their ability to race and foil the boat safely.
"New York Yacht Club American Magic have serious concerns that failures will occur during racing."
American Magic claimed that unless the problems were sorted out during practice this week, there could be "further failures during official racing, reputational damage, further claims before the Panel and possible disruptions to the Event."
American Magic also sought assurances that the data from their boat Patriot USA-5 would not be transmitted to opponents during practice racing, claiming it should remain confidential because it was outside any official event. The challenger of record Luna Rossa also argued practice racing was not official.
However, the panel has ruled otherwise, which means Team New Zealand must be included.
In an arbitration document which revealed the bitter nature of America's Cup sailing, Team New Zealand objected to the way the Italian syndicate referred to the defenders.
TNZ denied the Italians' claim that it had acted "improperly, unreasonably, illegitimately, opportunistically and petulantly".
TNZ claimed that proper racing was needed in order to test the Race Management System, including the umpiring electronics, and TV production.
The third challenger, the struggling British Ineos team, stayed out of the arguments, simply saying they were prepared to take part in any type of practice racing.
In response, race director Iain Murray gave assurances the issues which emerged during pre-Christmas sailing would be resolved, including the management of the spectator fleets around the high-speed AC75 foiling machines.
The event organisers, harbour master and course marshals would properly establish the racing areas, with good communication to the public, he said.
"Having America's Cup boats racing amongst the crowd is not acceptable – it can't happen and it won't happen," he said.
"We saw that on one day (in December), moving the course and people not knowing where that is. There's a lot of very complex equipment being used... really important pieces which need polishing up.
"In general the whole race management, getting the marks out there... we've had some things which need an upgrade and maintenance.
"There's always going to be software upgrades and debugging. Getting out today and tomorrow (in practice racing) and testing all of that, is important before race day."
Today's practice racing will be held on the outer harbour course E near Maraetai.
Heading into the Cup racing?
• Be aware that traffic will be busy, and parking will be very limited.
• Give yourself plenty of time and think about catching a ferry, train or bus instead.
• Make sure your AT HOP card is in your pocket. It's the best way to ride to the Cup.
• For more ways to enjoy race day, visit at.govt.nz/americascup.