A Christen Eagle II lost control during acrobatic maneuvers, collided with coastal waters and was never recovered. The airplane was observed in a steep climb, did a wing over, and then entered a spin. After 4 to 5 rotations in the spin the airplane started to pull out. The airplane was then observed rotating as if in a spin and simultaneously flipping nose over until its tail struck the water. The pilot's total documented aeronautical experience in the accident airplane make and model was 14 flight hours. Investigators determined that the airplane's weight exceeded the maximum normal and aerobatic allowable gross weight. The center of gravity (CG) exceeded the aft limit of the airplane's aerobatic allowable CG. The airplane flight manual publishes a warning which states in part; 'Pilots must take weight and balance responsibilities seriously. All aircraft must be loaded so that the aircraft CG will remain within safe limits at all times. All spin recovery procedures depend on having the CG remain within design limits.'