C-Side Surveyors (Stephen Iles) won the handicap division from Bart (Chris Smithers) and Chapman High Performance Sailing (Rod Childs).
"It was a fresh breeze and a tough day physically, so they all did well to get around the course and survive the night's festivities," Cohen said.
"I'm sure they all slept well after it. It was another successful day and a reminder of the rich history of this club and the 16ft class itself."
The Manly fleet will be divided this weekend, with up to 10 boats heading north for the annual Belmont regatta.
The remaining boats will face the starter's gun in Manly's ninth pointscore race of the season.