How Hydraulic Steering Works in Boats
If everything in a boat is functioning as it should, turning the steering wheel allows special hydraulic oil to pass from the helm into the hydraulic lines. While the boat has two such connecting lines, the oil passes into only one of these at a time with each turn of the wheel. Once the oil enters the cylinder’s main chamber, the rod inside will start to retract or push outward based on how the wheel rotates.
The hydraulic fluid flows out through the opposite chamber. Once this fluid leaves the cylinder block runs along the other hydraulic line in order to return to the helm unit. Thus, one chamber is always empty and ready to receive the hydraulic oil on its return trip through the system. While there may be various additional features in a given hydraulic steering assembly, they all have two main features in common: the cylinder unit and the helm unit. Each of these parts is connected to the other via tubes made of copper or nylon. The helm unit itself has two main parts that include a system of valves and a hydraulic pump.
It is this system of valves that keeps the oil that is exiting the chamber from coming back along the very same hydraulic line. These valves also keep the steering station isolated from other parts, lock the rudder in place and absorb any feedback from the rudder which might affect the helm. The double-action cylinders of the boat are available in balanced or unbalanced varieties. An unbalanced cylinder assembly has a rod that only extends through a single cylinder end. An unbalanced system will use one or more cylinders that move in the same direction as one another.
To determine how much strength is needed to pilot a hydraulically steered boat, one must test how many turns it takes to move the steering wheel from a lock-to-lock position. Finding the ratio between pump displacement, the volume of the cylinder and rudder movement will show how many turns of the wheel are needed. A wheel that needs only a few turns will respond faster but require more effort while slower response time won’t require a great deal of strength. Other variables that may influence steering in a hydraulic system include such things as:
- The speed of the boat.
- Dimensions of the rudder.
- The viscosity of the oil