If Steering wheel is rotated in clock wise, oil is pump out from the port ( right port from the front view) into the port of cylinder ( Starboard side ).
This cause the cylinder rod move to the port side, which move the boat to right side ( starboard)
Oil displaced from the opposite end of the cylinder flows back to the helm pump
For steering in the opposite direction, simply turn the helm pump the other way
When no course corrections are required, the inbuilt lock valve holds the engine stationary.