On a rescue mission, Capt Giorgos Marietakis only ever has one rule: to tune into his senses and envision the person he is out to save. On Sunday, he put himself into what he imagined would be the mindset of Kushila Stein, a 45-year-old New Zealand woman lost at sea for close to three days.

“I had an image of her being hungry and thirsty,” he said. “I tried to get into her head and think of what she would do. I imagined her beginning to despair and I thought of her doing whatever she could to survive.”

In 119, the rescue boat the Greek coastguard officer has captained for the past decade, he also knew every moment would count. Stein had been adrift for longer than anyone he knew. Although an accomplished seafarer, Stein had not been seen since 1 November when, driven by the desire to “stretch her legs”, she had left the yacht she was helping to sail from Turkey to Athens and rowed in a dinghy to the nearby island of Folegandros.

A text message from the Aegean isle was the last anyone had heard of her. Sent to Mike, the Englishman she was travelling with, it stated she was on her way back to the yacht. But that was before she had lost control of the inflatable dinghy after an oar had fallen overboard and then been driven off course by strong winds.

Marietakis, 46, knew she might be preparing for the worse. “We were brought in after seven vessels, a combat helicopter and military plane had failed to find her,” he told the Guardian from his base in Heraklion, the Cretan capital, on Tuesday. “All my thoughts were trained on finding this one human being. I knew that if we didn’t, she would probably not survive.”

In 19 years of heading search and rescue operations, the coastguard officer says he has learned to train himself to “focus solely on the senses where nothing else exists and you can almost see better and hear better”.

“We were looking for this little speck of a grey dinghy that in the ocean was so indistinguishable and so hard to see,” he said. “A plane and a helicopter had flown over the same area. She had spotted both and each time tried to catch their attention and they had missed her.”

It took Marietakis and his two-man crew more than four hours to reach the waters between Folegandros and Crete, 60 nautical miles north-west of Heraklion, where the dinghy was eventually found.

Stein, wearing a waterproof jacket, gym trousers and trainers, waved frantically. “She was clearly exhausted but very level-headed, very composed,” he said. “She had gone without fresh water and I think had begun to despair. She had survived on boiled sweets, which she had kept in a tiny pouch. By the time we found her, she said she had one left.”

The hardy New Zealander was wet, cold and dehydrated when the Greek rescuers lifted her to safety. Plainly fearing the worst, she had taken the precautionary measure of writing her mother’s name and contact details on the side of the dinghy.

But Stein, from Warkworth, north of Auckland, had also done everything she possibly could to survive – wrapping herself in the few plastic bags she had with her, rationing the boiled sweets, her only source of sustenance, and regularly drying out her socks – her mother, Wendy, told media outlets in New Zealand.

When search aircraft flew overhead, she tried to catch their attention by waving the one oar she still had.

“She had drifted a very long way, over 40 nautical miles south of Folegandros,” said Marietakis, adding that the crew gave her water, coffee and croissant as soon as she was on board. “She was so happy. She hugged and kissed us but, if truth be told, I don’t know who was more overjoyed, us or her. We had saved a human being and she had survived to tell the tale.”