A New Jersey sister and brother were thrown from their grandfather’s boat and killed after the kids asked to go back to his house after a family dinner out, according to court docs.

Stephen Schneider, 64, who was charged with double homicide last week, insisted to police he’d had only three beers at the two-hour outing on Barnegat Bay.

New Jersey courts redacted his blood alcohol level in the documents, but State Police confirmed after the fatal crash Schneider “was unfit to operate a motor vehicle and that his alertness, sense of care and caution, perception, judgment, response time and coordination were markedly impaired by alcohol.”

The children and their parents had taken their own separate boat to meet up with Schneider in his wife at MJ’s Restaurant in Bayville on July 19.

After dinner, the children, Mya Golabek, 9, and her brother Sigmund Paul Golabek, 7, wanted to go back to their grandparents’ house and the families split up.

On the way back, Schneider smashed his 30-foot Tidewater 280 into a wood channel marker and sent the kids flying into the waters around 9 p.m.

Both the kids were wearing life jackets, but they were found face-down in the water.

Schneider and his wife pulled the children from the water and started performing CPR, but they later both died at the hospital.

Schneider was charged Friday with two counts of reckless vessel homicide/death by vessel — a second-degree charge — as well as operating a vessel under the influence and reckless operation of a vessel.

Public records show that Schneider lives in a ritzy waterfront two bedroom three bath $1 million home in Bayville, Ocean County.