Occupying prime position for day one in the middle of the bay were the IRC1, IRC0 and J109 fleets, sailing a single race on their windward-leeward course just south of the harbour entrance.
In the one-design J109s, the event began with a local hero, or two, in fact. Peter Redden's Jetstream, helmed by son Simon, crossed the finish line after two rounds with a handsome lead but was disqualified for a false start.
"We were second around the first windward mark and went right on the first downwind, then in out of the tide up the beat," said Simon.
"That's where we made all the gains, we were miles ahead of the rest, so to be called out was a real kick - we're sick, but there's always tomorrow."
That gifted Jalapeno the win, with Belfast boat Juniper in second, having led around the first mark of the course.
In IRC 0, Tim Costello's Tiamat ran away from close rival Anthony O'Leary from Cork, however a results discrepancy meant the final result would not be confirmed until late last night, and revised results gave British entry Quokka the win on corrected time.
Fighting fire with Munster fire, Costello had Crosshaven duo Prof O'Connell and Mark Mansfield in the cockpit with him.
"I reckoned they'd know what tricks he'd pull," said Costello, who hoped his own local knowledge would pay as he directed them for shore out of the tide.
"We were going off the pin and left, but unfortunately the breeze flicked right, and was trending right of where the course was laid," he said.
O’Leary’s son Robert duly took IRC1 in their converted 1720, Antix Beag.
Across the bay in the Sutton course, the SB3 and J80s had two races and were battling the conditions as much as each other.
"It was very, very shifty" said local sailor Aidan O'Connell.
"We had a 50-degree shift in the second race - results were very up and down."
Sean Craig of the Royal St George posted a win followed by a seventh in the second race, which keeps him in second place behind Kiwi helm Ben Duncan.
"Sean sailed well in the first race and deserved the win,” said Duncan.
“We were delighted to take the second, it was pretty shifty out there, especially in the second race and the standard of the competition is right up there."
The forecast for Friday is for extremely light and variable conditions on the Bay, with stronger breeze forecast for Saturday and Sunday.
Select results from Dun Laoghaire:
1st After You Too
1st Squalo Bianco
3rd Tiger Lite
1st Ruff Nuff
3rd Ruff n Ready
1st Butlers Ball
2nd No Name
3rd All Balls Hell Fire
1st High 5
3rd Fifty Somethings
3rd Glen Marisa
1st Toy for the Boys
1st Tiller Girl
2nd Bean Adhmaid