Mercury Mariner 200, 225 Optimax Outboards Service Manual, 90-855348, Page 52Get this manual
Propeller Installation If the propeller shaft is rotated while the engine is in gear, there is the possibility that the engine will crank over and startTo prevent this type of accidental engine starting and possible serious injury caused from being struck by rotating propeller, always shift outboard to neutral position and remove spark plug leads when you are servicing the propellerFlo-Torq Drive Hub Propellers
Trim "In" Angle Adjustment
Some outboard boats, particularly some bass boats, are built with greater than normal transom angle which will allow the outboard to be trimmed further "in" or "under"This greater trim "under" capability is desirable to improve acceleration, reduce the angle and time spend in bow high boat attitude during planing off, and in some cases, may be necessary to plane off boat with aft live wells, given the variety of available propellers and height range of engine installationsHowever, once on plane, the engine should be trimmed to more intermediate position to avoid bow-down planing condition called "plowing"Plowing can cause "bow steering" or "over steering" and inefficiently consumes horsepowerIn this condition, if attempting turn or encountering diagonal, moderate wake, more abrupt turn than intended may resultIn rare circumstances, the owner may decide to limit the trim underThis can be accomplished by purchasing stainless steel tilt pin (PIN 17-49930A 1) and inserting it through whatever pin hole is desiredThe non-stainless steel shipping bolt should not be used in this application other than on temporary basis!!