What are the differences between “Add-ons,” “Self Contained Hydraulic” and “Full Power Hydraulic” steering?
The Add-on system is an economical alternative to the Full Power System on Mercury MerCruiser stern drives with factory power steering. External steering cylinders are hydraulically connected to the controller valve on the inner transom plate and the stock steering cable and helm are retained. Steering effort is low, but with play in the steering of the drive, the system is not as responsive as the Full Power System. In the Self-contained Hydraulic system the helm functions as a pump — turning the steering wheel causes the fluid (which is stored in the helm) to be pumped to the cylinders. Control is positive and smooth and plumbing is simpler than power assisted systems but the steering effort is greater. The Full Power Hydraulic system is 100% hydraulic with power assist. The pump provides system pressure to the helm, which diverts oil under pressure to the cylinders when the wheel is turned. Steering effort is low and the steering wheel is isolated from propeller torque. This system
