"The concern was its getting dark and you're running against the clock," Dr. Steven Hamman said.
Hamman became worried after Canton went windsurfing around 5 p.m. and had not returned after 6 p.m. Caton is an experienced windsurfer and was wearing safety equipment and a floatation device.
"I had been looking through my binocs and I saw nothing," Hamman said.
Hamman says he was worried about his wife's strength. She is a cancer survivor who is undergoing chemotherapy.
Hamman called 911. Police and fire crews responded. The Coast Guard launched helicopters and boats. They searched through the night -- 82 square miles from Coyote Point to the San Mateo Bridge.
The water temperature was a relatively warm 72 degrees and Caton wore a flotation device on top of her wet suit.
Hamman says one Coast Guard boat came within 50 feet of Caton.
"She was yelling and she was lifting her board up to get their attention," he said.
But it was dark, the waves were choppy and Caton's emergency gear had also failed.
"The radio failed, the strobe failed; my wife failed to realize she had a whistle and they would have heard her probably," Hamman said.
At first light around 6 a.m., a Coast Guard chopper saw something north of the bridge.
"We saw the board first, we didn't necessarily see she was still clinging to it," Coast Guard co-pilot Lt. Jr. Grade Dave Stern said.
"She was floating, draped over the board and that was another key to her survival, having the right flotation," Coast Guard Petty Ofc. Gabe Pullian said.
Pullian was lowered into the water to pick up Caton.
"I just told her we'd been looking for her all night; she just said, 'I know,' and just asked her if she was OK and she said, 'Yes, I'm just ready to get home,'" Pullian said.
On shore, his nerves spent, Hamman heard the sweetest words over the marine radio.
"The all clear, so that was very good, it was a good moment," he said.
Canton says her sail failed while she was in the water and she became stranded when she was unable to piece it together. At one point Hamman says his wife considered swimming to shore, thinking it would take about two hours but decided against it because the water was too choopy.
When asked if he thought his wife would ever go back to windsurfing, Hamman says he is sure she will after a few days rest.