Tim Wadlow pointed his 49er skiff toward the starting line, thinking he had hit it just as the clocked ticked to :00.
"You've got to be in the front row or it's going to be a long race," Wadlow said.
But he overshot the line by a tick of the clock, and it was race over.
The disqualification dropped Wadlow and Pete Spaulding from seventh into a tie for 12th in the 19-boat fleet.
In sailing terms, it's called being "on course side," or OCS.
"We almost had a solid day going but the OCS didn't help us," Wadlow said. "But you've got to stay aggressive on the starting line. We pushed it just a bit too hard today."
Paul Foerster and 470 class crew Kevin Burnham remained in second but dropped to six points behind Britain's Nick Rogers and Joe Glanfield with three races to go.
Yngling skipper Carol Cronin won the seventh race of her 11-race series, but then finished next-to-last in the 16-boat fleet to drop into 12th overall.
On the Europe course, Meg Gaillard also had a good-bad day, finishing third then 13th. After six of 11 races, she's eighth overall.
Kevin Hall of Bowie was 13th and ninth in the Finn class to drop to 15th.