Irishman Nick Dwyer, 55, and Frenchwoman Barbara Heftman, 44, were sailing from New Zealand to Australia.
Australian police rescued the pair 210 nautical miles (390km) off Sydney amid 6m swells and gale-force winds.
The sailors, on a circumnavigation of the globe, had activated an emergency beacon in turbulent seas on Tuesday, three days after their rudder broke.
"We encountered enormous seas, waves the size of buildings coming at you constantly, winds that you can't stand up in, seas breaking, whiteness everywhere," Mr Dwyer said.
Mr Dwyer said the couple's 40ft (12m) yacht "rolled" on Tuesday, prompting them to issue a distress call.
"We weren't sure whether we were going to be rolled again and each time a wave hit we thought, 'is [this] the one that's going to take us?" Mr Dwyer said.
After receiving the distress call, the Australian Maritime Safety Authority (AMSA) sent a jet to the remote location before asking police for help.
New South Wales Police said it took their rescue boat more than 13 hours to reach the pair amid "treacherous conditions".
"It was truly amazing, to think that somebody had to come that far to save us," Mr Dwyer said after arriving in Sydney on Wednesday night.
"I owe them my life. We owe them our lives. You can't put that into words."
AMSA had been in regular contact with the experienced sailors since their rudder failed on Saturday, police said.
The pair, who had been on a 10-year circumnavigation, will remain in Sydney while figuring out what to do next.
"Our home's gone, we're alive, I expect to live a little bit longer and that'll be okay," Mr Dwyer said.
A couple has told of facing "waves the size of buildings" when their yacht broke in remote seas off Australia.