A search will resume today for a man thought to have drowned early Sunday when he fell out of a boat during a camping outing along the Kansas River northwest of Lawrence.

The presumed victim was Thomas Portenier Jr., 38, Leavenworth, Douglas County Sheriff Rick Trapp said.

“It’s my understanding the gentleman was experienced on the river and was on the river a lot,” Trapp said.

About 5 a.m. Sunday Portenier left three companions he had been camping with along the river about 2.5 miles northwest of the Bowersock Dam and got into a fishing motorboat, Trapp said. He may have been checking fishing lines.

Minutes later his camping buddies heard the sound of a crash and the boat’s motor running at full throttle, Trapp said. They used a cell phone to call for help.

Their identities weren’t released.

“I don’t know that anything went wrong with the boat,” Trapp said. “There may be a possibility it struck a tree and knocked him out of the boat.”

Firefighters from Lawrence-Douglas County Fire & Medical and Douglas County Sheriff’s officers found the boat against the bank.

Despite searching most of the day along the banks and in the water from the accident area to the dam, there were no signs of Portenier, Trapp said.

Joining in the search were Kansas Department of Wildlife and Parks officers and the Douglas County Underwater Search and Recovery Unit, consisting of Lawrence Police and sheriff’s officers.

Trapp described the river as treacherous because of underwater currents and debris, especially for the dive team.

“When you are under the water you can’t see your hand in front of your face,” he said.

The search for Portenier was called off about 3:30 p.m. Sunday, Trapp said.

“All of the area that can be searched has been searched,” Trapp said. “The dive team has been in the water for two hours. The boats have been out since early this morning.”

Searchers were aboard two Wildlife and Parks boats and one boat from Fire & Medical, Trapp said. Another Fire & Medical boat was kept in the area as a reserve.

Today’s search will continue this afternoon when water conditions are at their best, Trapp said.