"Since the last race of AC35, I've been thinking every day about the America's Cup," Spithill said in an interview with his sponsor Red Bull.
"Naturally, you go over the previous campaign piece-by-piece, focusing on all the key moments and decisions during the four years. Lately I've been able to understand how a lot of the other teams operated, and that in itself is very educational.
"Ultimately, two things stood out for me: trusting my instincts is key, and the hunger has only gotten stronger.
"It's great to be back with Luna Rossa Challenge. I have a lot of great memories from the four years we spent in Valencia during AC32, and this time I have been impressed with the tools, technology and people they have in place," he said.
"It's a great mix of experience, new energy and enthusiasm in an open environment – the makings of a great team."
He said the new foiling monohulls were going to be beasts. ''It reminds me of America's Cup34 and the AC72 foiling catamarans. Nothing like this had been done before, and this boat is on the cutting edge of technology."
The rules around the design of the new Cup yachts are due out on March 31.
Emirates team New Zealand are expecting six challenges for the Cup, with Italy's Luna Rossa, Britain's Land Rover Ben Ainslie Racing and New York Yacht Club entry Bella Mente Quantum Racing already confirmed.
Team New Zealand boss Grant Dalton says another had signalled their intention to enter but public release was being left up to the individual syndicates.
There has also been interest from China, Japan, Australia and another US syndicate.
Potential challengers have until June 30 to enter.
