I recently picked up a new to me 1998 Horizon RS (18'). Is is moored in freshwater lake. Please see the picture. It is noticeably listing to the right. Bilge is dry. I suspect very slow leak maybe hiding water? is this possible. Water logged foam maybe? I am not too familiar with construction of boat is below floor, but looking for some input as to possible causes, how to diagnose, and solutions. Thanks for the help

