Hydraulic Autopilots

How does a hydraulic autopilot work?

- Powerful and reliable: Hydraulic autopilot systems for motorboats and sailing yachts -

Find out everything there is to know and more about autopilot hydraulic steering here: A hydraulic autopilot is integrated into your boat's hydraulic steering system and automatically steers it according to preset data from the course computer. It consists of a hydraulic pump, control cylinders and a control unit that is connected to the course computer. Modern autpilots feature all number of advanced sensors that ensure reliable operation.

To understand how a hydraulic autopilot works, we first need to take a look at the structure of a hydraulic control system: Such a control system consists of a steering wheel pump that is connected to the steering wheel. Two hydraulic lines lead to a control cylinder, which is connected to the rudder via a piston that moves the rudder. This is the usual set up, with the piston controlling the rudder. When the wheel is turned one way, fluid goes through the circuit in one direction, when you turn it the other way, fluid goes the other way. The pressure from the system pushes the ram either one way or the other, depending on which way the wheel is turned.

A hydraulic autopilot also has a hydraulic pump that is connected to one line each of the control system with two T-pieces. A control unit connected to the course computer (usually via NMEA2000 interface) operates the pump and the rudder. It is important that the control wheel pump contains a check valve so that the autopilot can operate autonomously in the system. If no such valve is available, a Dual Check Valve must be fitted. When the autopilot is not active, the valve still blocks and will not have any affect on steering. A balancing or equalising line connects the hydraulic pump of the autopilot to the highest point of the control pump, thus ensuring the system is vented.

Some boats are equipped with an emergency tiller which, if necessary, is fitted in the control shaft and can be used if you can't steer with the wheel for some reason. A bypass valve must then be installed in the system so that hydraulic oil can circulate in an emergency.

How do I find the right hydraulic autopilot for my boat?

- Buying a hydraulic autopilot: Some basic considerations are important -

Because of its size, it is recommended to install your autopilot below deck on boats longer than 34 feet (approx. 10 metres). Experts recommend using the same manufacturer as your course computer / plotter, if you already have one. The same applies to any hydraulic control system already installed, use the same manufacturer.

The size of the system (autopilot pump) depends on the force that a hydraulic autopilot must apply - the control cylinder must therefore correspond to the torque of the rudder. Other things to consider are displacement of the boat, rudder blade size, type of rudder blade suspension and maximum speed of the boat. If there are two rudder blades, the required force must be combined. Autopilot manufacturers often provide size specifications that might not be accurate - for example, specifications are usually based on an empty boat. For this reason, it is usually better to make your own calculations and base on a size that is a little larger than specified. It's not advisable to go for something where equipment is pushed to the limits. Try to go for a more powerful device to avoid wear and tear due to overloading. Furthermore, if a lot of hydraulic oil has to be moved through the autopilot pump unit so that the rudder can be turned from stroke to stroke in about eight seconds (corresponds to an ideal value), a correspondingly large hydraulic pump is needed. There are plenty of YouTube videos that offer advice on this.

Indications of the required pump size are also provided by the existing hydraulic control system, because there the cylinder size with cylinder volume in cubic centimetres (cc) is already indicated on the unit. On built-in machines you will find the cylinder on the rudder, on motorboats with outboards on the transom or on the engine itself. In any case, you will also find the data in the manual for the steering system. If two small hydraulic pumps are to be installed, the volume must be combined. Important: Large pumps consume more power than small ones, so the control unit with the course computer should be able to supply sufficient energy.

Before you decide to buy a hydraulic autopilot for your boat, you must take into account the electrical circuit on your boat and how it is set up: With a 12-volt system, all devices can be installed; with a 24-volt system, a specific selection must be made.

You might also be interested in: Autopilots and Accessories

In our shop you will find the right accessories for your new autopilot. In addition to the right autopilot accessory, installation accessories and spare parts, you will also find the displays & remote controls to control your autopilot hydraulic pump.