It should have been a routine summer patrol. On August 13th, 1979, a fresh young captain of the naval ship, LE Deirdre, was about 30 miles west of the Fastnet Rock off the south-west coast when he returned to his cabin from the bridge.
It was about 10 p.m., and sea conditions were relatively stable. He noticed something unusual. The barograph trace measuring atmospheric pressure had taken a dramatic dive.
"I checked it. It was ticking away and working. Nothing had been forecast. Over the next hour, it continued to dip."
So began a long night running into several days, as the first of a series of mayday calls were picked up by Valentia coast radio.
The international Fastnet yacht race, involving over 330 vessels, had been hit by a freak summer storm.
Now Flag Officer commanding the Naval Service, Commodore John Kavanagh remembers: "We just turned the ship around and headed for the rock."
The sailing fleet, scattered between the Scilly Isles and the Fastnet, was being mauled by mountainous seas which foamed and crashed around the granite lighthouse, and moaning storm force 10 winds.
According to Lloyd's, the marine insurers, 15 sailors lost their lives in the storm.
Beginning at the Isle of Wight, the Admiral's Cup race passes the Fastnet light and returns to finish in Plymouth. Of the 330 yachts at sea that year, only 54 were actually competing.
"Most of those were onlookers, and were completely unprepared for what happened, with many having no VHF radio on board," Commodore Kavanagh recalls.
It was something of a miracle that the death toll was not higher, and that 139 survivors were rescued, he says.
Though not assigned as guard ship for the event, the LE Deirdre played a major role in that rescue operation, along with the Dutch naval support ship escorting the race, the RNLI lifeboats, RAF helicopters and other vessels in the area, including the Irish Continental Line ferry, St Killian.
"Our first distress call was from a yacht named Wild Goose," Commodore Kavanagh remembers. The Deirdre and four lifeboats failed to find it, but the patrol ship then went to the aid of the Cork yacht, Regardless, owned by a businessman, Ken Rohan, which had reported it had lost its rudder and was in danger of capsizing.
The Deirdre stood by the yacht, about four miles off the Fastnet, until the Baltimore lifeboat arrived under coxswain Christy Collins. The lifeboat crew tried five times to get a line on board, only succeeding on the sixth attempt.
Regardless was towed back into the safety of Baltimore, while the navy ship moved on to assist other yachts in distress.
"We continued on a south-easterly course, with winds at storm force 10 gusting to hurricane 11," Commodore Kavanagh says. "The difficulty was that there was nothing but clutter on the radar during the night.
"From first light we began coming across yachts, all under bare poles, battened down and riding it out. In each case we asked them if they needed assistance, and for those with no radio it was a case of moving up close, sounding the siren, and communicating from the bridge using hand signals.
"A few were happy to sit tight till it blew over. Later in the day, down towards the Scilly isles, we found one abandoned yacht with no liferaft. It turned out that the crew's bodies were picked up. The liferaft wasn't storm-proof, and many of the boats found themselves in that position."
The lack of radio equipment, inadequate safety gear and yacht design were issues highlighted in the inquiry after the race, which resulted in a tightening of rules for the event. Commodore Kavanagh remembers his ship retrieving at least four rudders, "a new carbonfibre design which just snapped under the pressure".
The yacht designer, Mr Ron Holland, was one of 10 crew members winched from a liferaft by a British rescue helicopter after the rudder broke on the Golden Apple of the Sun, owned by the late Hugh Coveney.
Mr Holland, who vividly recalls how he was saved when a fellow crewman grabbed him by the hair, believes that the issue of yacht structure still has not been adequately addressed. He recently told the Examiner that there was still pressure on boat-builders to save weight.
Last December six yachtsmen died in the Sydney-Hobart race when a storm lashed that fleet in the Southern Ocean.
The log of the Deirdre records its long search over the next couple of days. On August 15th it located another Irish yacht, Silver Apple, 40 miles south of Roches Point, and escorted it in. Once again, it returned to sea and recovered a lifejacket, inscribed Alveria.
Some 50 minutes later, four miles farther south, a yacht of the same name was discovered, abandoned and rolling without its mast. The Naval Service took the hull under tow into Cork harbour. The crew members were never found.
"We continued searching, but it was hard work when there were no sails up. Just looking for masts was like looking for twigs against the horizon," Commodore Kavanagh recalls. For many years he kept the barograph chart which was nature's own record of the terrible storm, "shaped like an upended isosceles triangle".
As for the Deirdre itself, it is still serving in the seven-vessel Naval Service now under the command of Lieut Cdr Pat Allen, and just this week recorded yet another of many fisheries arrests.