On a boat, whether it is a sailboat or a motorboat, inboard or outboard, you can use a hydraulic system to steer it. Hydraulic steering has many advantages if it is well dimensioned:
- it does not require much effort for the helmsman
- it can steer large engine powers or even large sailboats with heavy canvas
- it is easy to install, as the passage of the hoses can follow complex paths
- it allows you to multiply the number of helm stations (fly for example, or inside steering, or double helm station on a catamaran)
Among the disadvantages, on a sailboat, it will be reproached for not offering a "return", a sensation for the helmsman.
How does it work?
A hydraulic steering system consists of 3 elements
- a cylinder that acts on the bar (or directly on the outboard motor)
- a pipe that carries the oil
- a manual pump (operated by the steering wheel or the wheel bar)
When the handwheel is turned, the pump behind it sends oil to the cylinder and makes it move. It is understandable that the volume of the pump must be proportional to the volume of the cylinder. This information is provided by the manufacturers. For example, there are 20 ml pumps. This means that one turn of the wheel will send 20 ml to the cylinder. If the cylinder has a capacity of 60 ml. It will take 3 turns of the handwheel to go from one stop to another.
Obviously, the cylinder must be sized according to the effort it must produce to turn the steering. If it is an outboard, the power and torque of the engine must be taken into account. A force exerted by the rotation of the propeller. This force can be cancelled out by counter-rotating propellers.
For inboard shaft drive, however, the rudder area, rudder trim and boat speed must be taken into account.
Suppliers provide charts and calculation models to determine the right cylinder for each configuration.
The assembly
Installing a hydraulic steering system is not difficult. Provided you have the right equipment. The hoses used are high pressure hoses. The conical fittings allow connections to be made without the need for special crimping pliers. Nevertheless, it is possible to order already crimped hoses if you know the exact lengths.
Attention, to ensure a perfect seal, all connections must be locked with blue threadlocker.
Finally, once the assembly is finalized, the hydraulic oil is filled through the pump (the flywheel) and requires a bleed at the cylinder to remove air bubbles.
Multiple steering wheels and power steering
One of the advantages of the steering system is the ease of installing multiple pilot stations. You just need to connect a pump on a branch of the circuit (with T connectors). This will be useful to install two helm stations on each hull of a catamaran or to put an external helm station on the fly of a speedboat in addition to the helm station under the wheelhouse.
With very large engines, you can also use a power steering system to help the pilot. In this case, it is an electric pump that comes on the circuit to support the pilot's steering movements. On a hydraulic steering system, an autopilot works in the same way with an electric pump directly connected to the hydraulic system.
