"I don't think anybody else would have picked it up but we've been married for over 50 years and I said to him, 'We need help now'."
Sheryl told crew her husband was having a stroke and they rushed Rex to the Sun Princess's onboard hospital. By the time they arrived - about 10 minutes after the stroke's onset - his speech had started to slur.
There, doctors gave Rex medication to dissolve a suspected clot and called in a rescue helicopter to evacuate him to Townsville Hospital.
The ship didn't have a landing pad so paramedics winched Rex - barefoot and dressed only in a shirt and shorts, with a metal cage to protect his face in case he hit the skids - to the helicopter as it hovered above the ship.
The day after the dramatic rescue Sheryl got off the ship at the next port in Cairns and flew to Townsville to be at her husband's bedside.
"The staff [on the ship] were absolutely brilliant. I could not fault them. They booked all the flights, motel and everything," she said.
He spent five days in hospital for tests and observation and made an "absolutely, totally, full recovery".
The couple refused to let the experience spoil their trip, and once the doctor gave Rex the all clear they flew to Darwin and got back on the Sun Princess.
Rex said he and his GP credited his amazing recovery to his wife's quick thinking.
The experience hasn't put the Farrows off cruising. This November they will spend the anniversary of Rex's stroke on another cruise. This time they're travelling around New Zealand.
"He's not allowed to do the same trick this time," Sheryl said. "I've told him."
The couple were thankful they had travel insurance and Sheryl said Rex's stroke highlighted its importance.
Her advice to others who thought a friend or family member might be having a stroke was: "get on to it as quick as you possibly can".
Rex said although he was a little upset about his stroke at first, he later realised how lucky he was.
"A cousin of mine had a stroke at a similar time and his stroke was much worse because he didn't get to medical [help] as quickly as I did."
Stroke Foundation chief executive Mark Vivian said the sooner someone having a stroke got medical attention the better because treatment reduced damage to the brain - and some treatments were time specific.
"[Time] can be the difference between a life time of disability, and a full recovery."
He said learning the symptoms of a stroke - known by the abbreviation "FAST" - was important.
"It takes a minute to learn, but it could make a lifetime of difference."
FAST stroke symptoms
Face drooping
Arm weakness
Speech difficulty
Time to call 111
Stroke facts
• About 9000 people have a stroke in New Zealand every year
• Fifteen per cent of people who have a stroke are institutionalised because of disabilities they cause and another 2500 die
• Strokes cost New Zealand more than $450 million, according to data from 2009
• Health authorities estimate the number of strokes every year could be halved, if people made better lifestyle choices around diet, exercise, alcohol and smoking