The water looked muddy, but with high temperatures and clear skies, Sunday was a good first day for Ryan Deer, a recent Mt. Lebanon High School graduate, to go boating on Cheat Lake in West Virginia.

The 18-year-old had driven the hour and a half down to the lake near Morgantown with five of his friends, all Mt. Lebanon High School graduates, for a day of boating and tubing. At about 5 p.m., they slowed down the ski boat to switch tube riders.

As they idled in the water, one of the other men on the boat with Mr. Deer pointed out a large maroon and white speedboat approaching them at high speed. Companion Peter Hric, whose father owns the boat and who said he goes boating frequently, on Cheat Lake and other area lakes, estimated the boat was going 20-25 mph as it powered toward them.

Moments before impact, Mr. Hric, who was standing at the end of the boat, pushed his girlfriend and Mr. Deer's girlfriend into the water.

"I just tackled them, open-armed grabbed them and threw them in the water," he said.

Two of the other young men on the boat jumped into the water, but Mr. Deer, seated at the front of the boat, did not have enough time to jump overboard.

The larger boat turned at the last minute, grazing Mr. Hric's boat and cracking the fiberglass, severely damaging the hull. Mr. Deer was thrown into the windshield of the boat on impact, lacerating his chin and right arm. For a few minutes, he thought his arm was broken.

"That's probably the most scared I've ever been," he said. "I'm sure all of us thought we were going to die. I just panicked.

"I'm thankful that I'm alive."

The maroon boat took off as quickly as it had arrived, Mr. Hric said. He got back on the his boat, and saw Mr. Deer, with blood dripping down his right arm and cuts on his wrist and chest.

His first impulse, Mr. Hric said, was to chase after the maroon boat and stop the people on it. Seconds before the impact, Mr. Deer saw six or seven people in the boat, and a woman sitting on the bow sunbathing. He said he was amazed she was not thrown off.

Pursuit was out of the question though, because the boat was filled with water and the side was badly damaged. Mr. Hric did not think the boat, which his family purchased new in 2002, was repairable.

The group brought their boat back to shore and called the police. Mr. Deer went to the hospital, where he was treated for cuts and bruising.

Hit and runs on the water are pretty rare, said Capt. Louis DellaMea of West Virginia Division of Natural Resources District One. The agency is investigating the incident.

"There could have been somebody killed," he said. "We don't call them accidents, because an accident is something that can't be avoided."

Anyone with information about the incident is asked to call the West Virginia Division of Natural Resources at 304-825-6787, or West Virginia State Police in Morgantown at 304-285-3200.