1999 "EE" Evinrude 70HP 4-Stroke Service Manual, P/N 787023, Page 151Get this manual
Trim Tab Adjustment- - &
Improper trim tab adjustment can cause difficult steering
A propeller will generate steering torque when it is not running
parallel to water's surfaceThe trim tab is adjustable to compensate for this steering torqueA single trim tab adjustment will relieve steering effort under only one set of speed, engine angle, and load conditionsNo single adjustment can relieve steering effort under all conditionsIf boat pulls to the left or right when its load is evenly distributed and engine is trimmed correctly, adjust trim tab as follows:
Important
engine shut OFF, loosen trim tab screwIf boat pulled to right, move rear of trim tab slightly to the rightIf boat pulled to left, move rear of trim tab slightly to the left
Tighten trim tab screw to 14 ftIbs(20 Nm) Test boat and, if needed, repeat procedure until steering effort is as equal as possible