"We tried to claw them back but just ran out of lake," he said.
He said they knew it was going to be a hard race and had a huge amount of respect for O'Conner and Flanagan, after rowing against them in the under-17 double.
The silver medal was the second gong for Rotorua crews after Hannah Cox collected bronze in the under-17 single sculls.
The Western Heights High School under-18 eight rowed the final event of the regatta competing for the prestigious Maadi Cup.
Although they won their repechage to qualify they finished eighth in the nine-boat final.
Coach Glen Reichardt said it was a particularly fast final with the top four all finishing in under six minutes.
He said the crew rowed an excellent race and posted their fastest finals time of the season.
Western Heights were the first Rotorua rowing crew to qualify for the A final of the eights since Rotorua Boys' High School in 2006.
Following the Maadi Cup Regatta four Rotorua rowers have won trials for the North Island under-18 team.
They are Broughton, Le Lievre, fellow medallist Cox and Sofia Morrell.