Mercury Mariner 4, 5 102CC Sail 1990 Outboard Service Shop Manual, Page 12Get this manual
Conditions Affecting Operation 1Proper positioning of the weig ht inside the boat (persons and gea r) has sign ificant effect of the boat's performancefor example:
aShifting weight to the rear(1) Generally increases top speed (2) If in excess, can cause he boat to porpoise
3Gear ou sing: If unit is left in the water, ma rine vegetatio may accum ulate over period lime in ce rtain types of waterThi growth must be removed from unit before opera tion, as it may cl og the water inlet oles in the gear housi ng and cause the engine to overheat