A 9-year-old Manassas girl died yesterday morning after being trapped inside her father's 20-foot boat, which capsized with five people aboard during a fishing trip on the Chesapeake Bay five miles southwest of Crisfield, Md.

A Coast Guard spokesman in Portsmouth, Va., said the girl, Sherra Carter, had been trapped inside the hull "less than an hour" before a rescue crew from Crisfield found the boat.

Her father, indentified as Jimmy Carter, was aboard the outboard-powered boat with Randy Mathers, 21; Tammy Tipton and Doreen Tipton, all believed to be from the Manassas area. All the survivors were in satisfactory condition yesterday, according to Coast Guard spokesman Michael Erdley.

They were were picked up shortly after 6 a.m. yesterday, after a passing sailboat reported sighting the craft overturned, Erdley said. Three were said to be clinging to the outside of the boat and two, one of them the girl, were trapped in an air pocket inside the hull.

The boating party had left the Point Lookout Marina at the mouth of the Potomac River about 7 a.m. Friday and was reported overdue in Baltimore that night. Coast Guard crews conducted an unsuccessful search all night, Erdley said.

A spokesman said the young girl was found unconscious when the Coast Guard crew reached the boat and apparently died after reaching Crisfield.

The spokesman had no immediate explanation why the fiberglass boat overturned, but noted that a boat of its size could easily have overturned in the bay's 10-mile-an-hour winds if its crew tried to anchor.