Here is the article from baynet.com. Since the driver of the big boat was cited for operating with no lights, and PWCs generally have no nav lights, we might surmise that it was dark and the 42 ran over the jetski.
The jury might have figured that even though the big boat driver was drunk, it did not cause the accident.
From baynet.com:
Cecil County - The Maryland Natural Resources Police continue their investigation of a boat accident that claimed the life of a Philadelphia woman.
On Saturday, July 21, at 4:11 p.m., NRP responded to the Elk River near Town Point for a collision between a 42-foot motor vessel and a personal watercraft (PWC). Kristy Lynn Szewczak, 21, of Philadelphia, Pa. and Christopher J. Leight Jr., 30, of Warmingster, Pa. occupied the PWC. Szewczak was transported to Christiana Hospital where she was pronounced dead. Leight was flown to the University of Maryland R Adams Cowley Shock Trauma Center in critical condition.
The operator of the 42-foot vessel, Mark D. Rosati, 51, of Mount Laurel, N.J. and his five passengers were not injured.
McMahan was issued citations for operating a motor vessel while under the influence of alcohol, operating a motor vessel while impaired by alcohol, operating a motor vessel while impaired by alcohol per se, operating a vessel between the hours of sunset and sunrise without proper navigation lights, and failure to have certificate of number available for inspection. He was released on his signature to a friend.