Mercury Mariner 200, 225 Optimax Outboards Service Manual, 90-855348, Page 494Get this manual
Trim Tab Adjustment DUAL OUTBOARDCOUNTER ROTATION INSTALLATION 1Shift outboard into neutral and make sure ignition key is at "OFF" position2Remove plastic cap from rear of driveshaft housing and loosen bolt and trim tab3Position trim tabs of both outboards straight to rear of outboard, so that tabs are aligned with gear housing centerline4Tighten both trim tab bolts securely and replace plastic capsNo further adjustment will be requiredDUAL OUTBOARDNON COUNTER ROTATION INSTALLATION 1Check trim tab position as follows: IMPORTANT: Initial trim tab setting for both outboards should be straight to rear of outboard, so that tabs are aligned with gear housing center lineRefer to "If necessary, adjust trim tab as follows," followingaOperate boat at normal cruise throttle setting and adjust trim to optimum settingbIf boat pulls to the right (starboard), trailing edge of trim tab must be moved to the right (when viewing outboard from behind)If boat pulls to the left (port), trailing edge of trim tab must be moved to the left2If necessary, adjust trim tab as follows: aShift outboard into NEUTRAL and make sure ignition key is at "OFF" positionbRemove plastic cap from rear of driveshaft housing and loosen bolt and trim tabIMPORTANT: Trim tabs MUST BE set in the same position on both outboardscIf boat pulls to the right, adjust trailing edges of both trim tabs to the rightIf boat pulls to the left, adjust trailing edges of both trim tabs to the left