America's Cup great Jimmy Spithill has broke his silence on Emirates Team New Zealand's innovative AC75 boat design predicting the monohulls to take the race to another level.

Spithill jumped ship earlier this year to rejoin Italian syndicate Luna Rossa after both winning and losing the Auld Mug with Oracle Team USA.

The Australian sailor, who famously destroyed one of Oracle's AC72s in a capsize ahead of the 2013 regatta, has remained unusually tight-lipped since the yacht designs were revealed.

But offering some thoughts to CNN's MainSail programme, Spithill has described the boats to be used in Auckland as "beasts".

The new boats are expected to be faster than the AC50's raced in Bermuda.
The new boats are expected to be faster than the AC50's raced in Bermuda.

"The speeds we could have… it'll be a beast of a boat. It's out there," Spithill said.

"This one will be another level."

"Will it work? That's the question. The America's Cup has always been at the leading edge of boats. Look at what's happened over the last decade. The AC72 kind of reminds me of this boat in that it is very, very powerful and never been done before."

"It's extreme, it's expensive, from first take, and what we are seeing, it's unstable, and it's going to be very, very physical."

The first of the new America's Cup boats are only due to be launched from March 31 next year but a video which emerged on social media last month has already given fans a sneak peek to the radical design on water.

The video posted to Facebook by London Corinthian Sailing Club appeared to show INEOS TEAM UK's first prototype.

The smaller QUANT 28 seen in the video looked stable in flight mode although it was not revealed whether the foiling is under manual or full computer control.

Sail-World reported that the prototype was sailing downwind at speeds of 30
kts in 12kts of wind, and upwind at 20kts while performing foiling tacks and gybes with relative ease.