Trapped in darkness, with freezing waters lapping at his feet and buffeted by 60ft waves, he will have known only too well that he was more than 1,000 miles from the nearest land.
Faced with the danger of being dragged down with the boat, and the terrifying sounds of the yacht's fittings coming loose and crashing down most people would have been tempted to try and jump clear.
Mr Bullimore's sense of calm developed from years of solo yachting experience taught him otherwise. He stayed with the yacht and quickly took stock of the few straws available for him to cling to.
Yesterday he described the horrific conditions he had endured in the creaking shell of the boat.
"You've got about two-thirds of the hull filled with water. There was a hole in the bottom of the hull, in fact really at the top, where one of the windows had come out, and it caused a vacuum.
"The hole caused water to be sucked in and out at a colossal rate, causing a kind of Niagara Falls, but upside down.
"I had to find myself a spot as high up as possible and put nets around it so that I could crawl in there and lash myself in to get out of the water and to get away from everything."
Dr Howard Oakley, head of survival and thermal medicine at the Institute of Naval Medicine, Alverstoke, Hampshire, said keeping a clear head and a sense of order were vital.
He said that having decided to stay with the yacht, Mr Bullimore's priorities were to activate the distress beacon transmitter and to ensure he was getting enough air.
As he perched in a makeshift hammock, trying to keep dry, Mr Bullimore was then alone with his thoughts, with nothing visible to focus on.
"There's nothing he would have been able to look at outside, so the movement he sensed would not be matched with visual stimulus. This is a classic situation that makes people motion sick."
Yet even the discomfort of sea-sickness while drawing breath from a few feet of air between the water level and what was once the bottom of the boat, could not break Mr Bullimore's remarkable tenacity and spirit.
"This chap is not an ordinary person, like you or me," said a clinical psychologist, Eileen Kennedy, from the Centre for Crisis Psychology in Skipton, North Yorkshire.
"The kind of person who takes part in a solo yacht race like this is going to be someone very sure of their own skills and experience and who lives a bit on the edge - someone who welcomes challenge and risk."
The yachtsman said that during the "horrific, traumatic experience" he was "hanging on in there and believing something would happen and just fighting."
Through four days of darkness and solitude, he depended on "sheer determination, a little water, a little chocolate" to sustain him.
Fellow solo yachtsmen, like Sir Robin Knox-Johnston, who described Mr Bullimore as a "tough little bugger", were confident that he would survive.
But even Mr Bullimore was at his endurance limit.
"I only just made it because of weather conditions, I was deteriorating at a reasonable rate," he said. "When I knew that the rescue was actually going to happen, I cannot explain it. I feel ecstatic. I thought it would never happen."Reuse content