Team New Zealand are challenging the legality of moves from America's Cup organisers to push through changes that would effectively alter the design rule just two weeks before racing is due to start.
Despite the teams failing to reach an agreement on all the proposed safety recommendations after four days of mediation, regatta director Iain Murray said on the America's Cup website he plans to implement all 37 proposals.
"As regatta director, I have a clear task. For me, safety means safety for everyone. Full stop. I stand behind all of the original recommendations to increase safety for all of our sailors this summer," said Murray.
"If the recommendations are included by the Coast Guard in our marine event permit then I will issue a regatta notice harmonising the various rule documents to reflect the safety recommendations."
But Team New Zealand and Luna Rossa are questioning whether Murray has the authority to make arbitrary changes to these documents, and are preparing to lodge a protest with the international jury.
While there has been speculation the sticking point during mediation was that of moving the start times forward, which would further lighten the wind range, the Herald can reveal the only recommendation Team New Zealand is opposed to outright is the issue of rudder elevators.
"We got pretty close to resolving all the issues," Team New Zealand managing director Grant Dalton said.
"We're not opposed to any of the rules that are genuinely there for safety. It's really down to one point and that is rudder elevators. We don't believe this change is in the interest of safety, we think it's unnecessary and it gives potential advantage to another team, for complicated reasons which no one would understand."
Dalton refused to say which team would be advantaged by the change.
The inclusion of a clause in the safety recommendations that appeared to allow the use of rudder elevators, which are prohibited under the original design rules, raised eyebrows from the outset.
It is understood Cup defenders Oracle have been using rudder devices for some time to assist the stability of their boat, which is not illegal at this point as the boats are still in testing mode. But as the rules stand, they would have had to remove these devices for the America's Cup finals in September.
Given the fatal accident occurred in Artemis' non-foiling boat, the design concessions appear more as an opportunity for Oracle to get their modifications ruled legal in the name of safety. For Team New Zealand the answer is simple: if teams can't find a way to foil safely within the rules, then don't foil.
The Kiwi team feel they have conceded a lot on safety recommendations, particularly around wind limits. They made trade-offs in their AC72 design to ensure they had a boat that would be reliable in the conditions originally set down under the Protocol, only to find the goal posts shifted after the Artemis accident.
What is a rudder elevator?
Rudder elevators are winglets attached to the ends of the rudders and look similar to the tail flaps on a plane, or adjustable spoilers on the back of a race car.
What the design rule says
Rule 8.6 - rudders shall not have components such as trim tabs or moveable winglets that can be adjusted while racing.
What will be allowed under the new safety recommendations:
1.3 Rudder Elevators
Minimum total area 0.32m2 per rudder.
Minimum depth of elevators on rudder span of 2.1m.
Maximum elevator span of 1.4m.
To be symmetrical in plan form and allowed to extend beyond maximum beam of yacht.
Permitted to be adjusted until warning signal.