Mercury Mariner 25HP 4-Stroke Outboard Service Manual 1997, Page 29Get this manual
Boat WEIGHT DISTRIBUTION 1Proper positioning of the weight inside the boat (persons and gear) has significant effect on the boat's performance, for example:
WATER ABSORPTION It is imperative that all through hull fasteners be coated with quality marine sealer at time of installationWater intrusion into the transom core andor inner hull will result in additional boat weight (reduced boat performance)hull decay and eventual structural failureCAVITATION Cavitation is caused by water vapor bubbles forming either from sharp edge or angle on the gear case or from an irregularity in the propeller blade 5e1These vapor bubbles flow back and colapse when striking the surface of the propeller blade resulting in the erosion of the propeller blade su rtace If allowed to continue, eventual blade failure (breakage) will occu r
aShifting weight to the rear (stern)