* Emirates Team New Zealand, Luna Rossa publish Class Rule
* Expect designs to lead to "fastest sailing monohull"
* Teams can launch their yachts from March 31, 2019
* Limitations on components that can be built by each team
By Alexander Smith
LONDON, March 29 (Reuters) - America's Cup defenders Emirates Team New Zealand and Italian challenger Luna Rossa started a race on Thursday to design the "fastest sailing monohull on earth" with a new set of rules.
The eagerly-awaited publication of the "AC75 Class Rule" by the Royal New Zealand Yacht Squadron and Circolo della Vela Sicilia defines the parameters for the foiling 75-foot yachts eligible to compete in the 36th Cup in Auckland in 2021.
While a major change from the futuristic "flying" catamarans in which Team New Zealand comprehensively defeated Oracle Team USA and captivated spectators in Bermuda's Great Sound last year, the return to monohulls represents a massive design and technology challenge costing hundreds of millions of dollars.
Luna Rossa, the "Challenger of Record" which is backed by Italian fashion house Prada, and the New York Yacht Club, which will compete as "American Magic" have both officially entered the competition for the "Auld Mug".
Britain's Land Rover BAR, led by Ben Ainslie, is in the process of preparing its own entry and is making a scale model of the boat it plans to build to try to win the coveted cup for Britain for the first time in its 167-year history. Ainslie told Reuters that his challenge would cost at least 100 million pounds ($140 million).
"We have done a great job containing costs on certain aspects, while leaving the rule open enough for the America’s Cup to continue as the driving force of innovation and technology in sailing," Dan Bernasconi, Design Coordinator for Emirates Team New Zealand, said in a statement.
Designers and builders from the teams will now dissect the details of the rule and have a year to work on their plans before they can officially launch their individual yachts.
The rule includes strict limitations on the number of components that can be built by each team including hulls, masts, rudders, foils and sails.
This would encourage teams to use simulation rather than physical design and testing to complete R&D, Team New Zealand and Luna Rossa said in a joint statement.
"The (rule) sets the parameters for the teams to develop and race the fastest sailing monohull on earth," said Martin Fischer, Design Coordinator for Luna Rossa Challenge. ($1 = 0.7134 pounds) (Editing by Ed Osmond)