The 1979 Fastnet Race began in what were calm conditions - conditions that were not expected to present a great challenge for the 303 boats taking part in the 600-mile voyage.
The track would take the boats out towards the Isles of Scilly and then on towards the Fastnet Rock - the turning point - before heading back to the finish at Plymouth.
The bigger boats could make it in six days.
Among the high-profile competitors were former British prime minister Edward Heath, Ted Turner of CNN-fame and pop star Simon Le Bon.
Apart from the more professional crews, there was a mixture of competent sailors - sailors who were less than prepared for what was to come.
The fleet left the Isle of Wight in windy conditions on 11 August, which was promising for sailing and competitive racing.
In those days weather forecasting was far more limited than it is today. No one anticipated a violent storm coming in across that Atlantic.
Or that when it reached its most extreme force - just below that of a hurricane - the Fastnet fleet would be at its centre.
On 14 August, a fog near the Fastnet lifted and the sea was - in the words of lighthouse keeper Gerald Butler - "flat calm".
However, a strong wind came from the south and continued to build throughout the day.
Weather forecasts began to warn of more treacherous conditions.
For many in the Fastnet fleet, those warnings would come too late or not at all. VHF radio was an expensive piece of equipment and therefore a rare one.
By 10pm that night the winds had increased significantly and by midnight they were approaching Storm Force 11. Waves were between 40 and 50 feet high.
From his position below the light of the Fastnet Rock, Mr Butler could no longer see what was below him because of the waves, foam and screeching winds.
At one stage, standing at nearly 150ft and just below the Fastnet light, he said he felt he could "almost touch one boat", so high was she in the water.
All night he listened to the radio, hearing cries for help and accounts from boats passing others that had been abandoned or had sailors clinging to their hulls.
It was that radio traffic that Sally O'Leary, one of about three women among the thousands of male competitors, found most frightening.
"We could hear the distress calls all night. Apart from being tossed around in the boat, that what was most frightening," she recalls.
She was aboard her father, Sir Robin Aisher's boat, Yeoman XX1.
Aisher was an Olympic medallist and one of the most accomplished sailors in Britain.
Ms O'Leary remembers him calling for help that night when he could no longer steer the boat alone.
He wisely abandoned his race before they reached the Fastnet and limped for England with no sails.
While conditions around the Fastnet were atrocious, it was nearer to the Scilly Isles that the storm was at its most threatening. It was also in this area that most of the less-experienced and smaller boats were located at the back of the fleet.
Neil Kennefick was a member of the crew of 'Golden Apples of the Sun', a Cork boat fancied to win not just the race itself, but the Admirals Cup Series, of which the Fastnet Race was the last.
A well-prepared and well-practised crew, they were ahead when they rounded the Fastnet with skill and determined seamanship.
Having rounded it, they headed for Plymouth with the wind behind them and their anxiety assuaged by confidence.
The next day, with the storm still raging, Kennefick looked behind him to see the wheel in the cockpit spinning around in the hands of helmsman, Ron Holland.
A frantic repair was performed, which got them through the next five hours. Then they lost their rudder as the carbon cracked. The boat was out of control.
Throughout the night, the scale of the tragedy unfolded. More than 150 boats were reported missing.
Many of those who had effective radios were screaming for help as the seas overwhelmed them, brought them up cliffs of waves the height of tall buildings and then plunged them back into troughs of the same depth.
Crews were experiencing conditions in which they could barely sail and which several would not survive.
Many boats did not have proper radios, safety harnesses broke, the lack of experience of ocean sailing became apparent and many abandoned ship and took to life rafts.
The rafts were tossed about on the waves for hours. This is why so many died.
"Only leave your boat when it sinks or you step up to a lifeboat, a rescue ship or a helicopter", reflects Kieran Cotter, a crew member on board the Baltimore lifeboat that night.
Those who could stay with their boats were the ones who did survive.
Today marks the 40th anniversary of the Fastnet Yacht Race disaster in the Irish Sea. Nineteen people lost their lives as boats were tossed about in 40 foot waves and near-hurricane force winds | https://t.co/FPh7aKAgqd pic.twitter.com/609ZBRBRan— RTÉ News (@rtenews) August 14, 2019
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By morning, more than 100 had been saved by a rescue armada that involved everything from the Irish Ferries ship, St Killian, helicopters from the Royal Navy, lifeboats from all over the south coast of England and Ireland (the Ballycotton crew would stay at sea for almost 24 hours), trawlers, naval ships from Ireland, France and Holland, and planes from France and Britain.
It was the biggest search and rescue mission ever in peacetime Europe and covered an area of 32,000 square kilometres.
Neil Kennefick and his fellow crew members, realising they could do no more to control their boat, sent out a distress signal. The effort to gain victory in the race instead became a fight for survival for the ten of them.
The signal was picked up by a freighter en route to Newfoundland, but such was the height of the waves, they could not board it. A Royal Navy Sea King helicopter eventually arrived.
The pilot told them ominously: "If you're coming, come now. I'm low on fuel."
At that point, the mast of their yacht was being blown down on to their raft. The pilot swung the helicopter sideways to blow the boat off them with the wind force from his main rotor blade.
"I saw the winchman just above me. A minute later he was 40 feet above me because of the height of the waves. I’ve never seen waves like them and I never want to see them again," Neil said.
When the battered boats had reached safe harbour or even Plymouth, it was then that the survivors became aware of the scale of what had happened. Until then, each had been consumed solely with their own survival.
A Dutch naval vessel brought bodies ashore in metal coffins. The casualty count began.
Fifteen crew members lost their lives, as did four who had been on board a boat shadowing the race. All had either drowned or died from hypothermia.
Their names are recorded on a memorial stone on Cape Clear Island, the nearest land point to the Fastnet.
The 1979 race led to many changes in the rules and regulations governing ocean racing.
Crews competing in the Fastnet must now pre-qualify and have a required level of ocean experience, VHF radio became a requirement after the race and even the way survivors are lifted from the sea was revised to ensure blood does not rush to the legs.
Could it happen again? Yes, but such a storm would be forecast well in advance and the consequences might not be as fatal.
But the sea remains capable of what has been described as its great fury.