1999 Volvo Penta "WT" Models Workshop Manual, Page 315Get this manual
After the problem has been found, determine the causeFor example, if the fluid level in the reservoir is found to be low, refill and bleed the system and check the entire hydraulic system for leaksJust refilling the reservoir will make the unit operate, but will not correct the condition that caused the problem Trim Tab Adjustment
Models With Power Steering
Trim tab adjustment is not required on power steering installations
Models Without Power Steering
Safety Warning: Improper trim tab adjustment can cause difficult steering
An adjustable trim tab is provided to compensate for propeller torque and allows you to balance steering effort in either directionTest your boat to see if further adjustment is needed With firm grip on the steering wheel and the weight in the boat evenly distributed, run the boat at full throttle in straight lineDo this in an area where current and wind will not be factor Turn the steering wheel to port and starboardDetermine which direction requires the least amount of steering