Ainslie had a strained relationship with Manchester United co-owner Ratcliffe regarding plans for the 38th America’s Cup.
Ainslie told the BBC on Tuesday that splitting with Ineos after the “fallout” was “a difficult decision” but stemmed from “different opinions on how to move forwards with the team”.
Ainslie, who will retain significant shareholding in Athena Racing under the new investment and remain as team principal, said he had been “funding the team myself”.
He told Reuters: “It’s been pretty stressful. But I believed in the team, I believed in the partnership and I was willing to take that risk.”
Ainslie was Ineos Britannia’s team principal and skipper, having got the backing of Ratcliffe in 2018 in a bid to a deliver a first win for Britain since the America’s Cup started in 1851.
The most successful sailor in Olympic history, Ainslie won the America’s Cup in 2013 with Oracle Team USA.
On Monday it was announced that the America’s Cup would be held every two years after 2029 and there will be a 55m euros (£48m) cap on costs, after the five founding teams, including Athena, formed an alliance.
Describing the move as “groundbreaking”, Ainslie said he was confident the new structure would help attract further investment and interest from broadcasters.
“Traditionally America’s Cup has been a winner-takes-all environment,” he said.
“You win it, you effectively run the next event – you decide where it is, when it is, the size of the boat, the rules and regulations.
“It’s pretty quirky – that’s what created a lot of uncertainty. Now we’ve changed that.”