Police found a disabled 26-foot boat in the Potomac River south of Alexandria early yesterday and charged an 18-year-old Alexandria man, who they said tried to swim away from thith stealing it.

The boat, owned by the U.S. Geological Survey, had been stolen from the Franklin Street Piokesman Carson Dunbar said.

A search began when people standing on the Woodrow Wilson Bridge reported to D.hey saw a disabled boat north of the bridge, according to Dunbar. After a police boat failed to find the vessepolice helicopter about 1:30 a.m. 2 1/2 miles south of the bridge, he said.

The boat's steering apparently wearing a life jacket jumped into the river and started swimming toward shore as the helicopter approached, acid the man was pulled from the water by police who arrived in a boat.

Charged with theft of government proper, 18, of 615 S. Pitt St., Alexandria. He was later released on his own recognizance.

The FBI said others th stealing the $30,000 boat, which was scheduled to be used yesterday for sampling Potomac River water quality, according to Ward Hickman of the Geological Survey.

Two other boats that had been docked at the Franklin Street Pier--a 16-foot Geological Survey Boston whaler valued at $16,000 and a ce found in the river, and the FBI was investigating to see whether they had been stolen.