New Zealand won the trophy for most medals across all three World Rowing Cup regattas, despite competing in only two.
It was the first time on the podium for the women's eight since last year's third regatta, although the United States and Russia did not compete last weekend.
In any case, it bodes well for qualifying a New Zealand crew next month to make the 2016 Rio Olympics.
"This is a major stepping stone," said Scown.
"We're such an inexperienced crew so to win a heat and then take silver in the final is the most important thing we've done.
"I love sitting in the stroke position because I feel so confident in the group behind me. I just support the rhythm they create."
The national selectors had faith that 21-year-old Gowler and 23-year-old Prendergast would have the stamina to pull double duty in Lucerne.
"It's the first time we've done it, so it's exciting," Prendergast said. "It helped that we avoided a repechage in the eight to conserve energy."
Gowler and Prendergast had won bronze at the second World Rowing Cup regatta in June, behind Great Britain and the US.