Hydraulic Steering, Autopilot and Mechanical Steering Integration

Our Pan Oceanic 46 pilothouse sailboat came with conventional cable steering on the pedestal in the cockpit. A second hydraulic steering station was located in the pilothouse. The pilothouse configuration was one of the reasons we purchased the boat. It provides a nice warm place to steer the boat in rainy or cool weather.

During the refit all the old copper tubing and controls for the pilothouse hydraulic steering system were removed.  New hydraulic hoses and fittings were purchased to rebuild the system.


Hydraulic Steering Pump
The wheel driven hydraulic pump in the pilothouse is a Teleflex Capilano 1275v. The pump is mounted on the helm station in the pilothouse.  When designing a system make sure your steering pump is sized to handle the pressure and volume ratings of the hydraulic cylinder.

As the wheel is turned the pump drives fluid through the two main lines to drive the hydraulic cylinder either in or out to move the rudder and steer the boat.

Hydraulic Cylinder
The hydraulic cylinder we have is a Teleflex BA-200-7. We had it rebuilt so all the seals and O rings were replaced. It has a 7 inch stroke and will handle 13,200 inch lbs of torque at 1000 psi (70bar).  This cylinder will be driven by the pilothouse hydraulic steering pump and the electric autopilot pump.

In the picture you will see the hydraulic cylinder with the mechanical connections on the right and left sides. The left side will be connected to the rudder quadrant and the right side will be fixed to a bulkhead near the rudder in the aft end of the boat.

The green handle is a manual bypass valve and the black square is an electric hydraulic solenoid bypass valve.

The hydraulic hoses connect to either side of the cylinder on the brass fittings.

Having both a manual cable steering system and a hydraulic system has it's complications. In normal operation the main mechanical cable driven wheel steering will be used to steer the boat from the cockpit. In this configuration the hydraulic system needs to be bypassed to allow the fluid to flow around the cylinder. This will prevent drag on the manual steering system and motoring of the hydraulic steering wheel.

When the autopilot is engaged or if the pilot house hydraulic steering is used a bypass valve needs to be closed to allow the fluid to drive the cylinder.

The hydraulic solenoid bypass valve is normally open, but when the autopilot is engaged the electric solenoid bypass valve will close allowing the autopilot pump to drive the cylinder and steer the boat. The manual green lever is a backup for the electric solenoid bypass valve and basically does the same thing.

In the case when the pilot house steering is used a separate switch was installed to engage the electric  solenoid bypass valve which will allow the pilothouse steering pump to drive the hydraulic cylinder.

Hydraulic Hose
The old hydraulic system was put together using copper tubing.  Solid tubing is good in that it does
not flex and cause the steering system to feel spongy. As it ages it may become brittle and break if flexed too much. Most modern systems now use high pressure plastic tubing or hose.

We chose to use flexible hose because it is easy to cut, make connections and route through the boat.  Flexible hose is readily available at any hydraulic store. The connectors are reusable and are easily screwed onto the ends of the hose.

Autopilot Equipment
A hydraulic autopilot system was integrated into the hydraulic steering system. A Raymarine Type 2 autopilot pump was paired with the existing Teleflex hydraulic cylinder which will drive the rudder.

The boat weighs 34000 lbs so the larger Raymarine ACU400 autopilot unit was needed.  This can power either a mechanical linear drive or a hydraulic pump as it does in our system. It is powered by 12 volts and requires a 40 amp breaker and the appropriate conductor size.

The ACU400 is tied into the NMEA 2000 network and can be configured to power the network as we did in this case. The ACU400 can be purchased online at several sites for about $1300.

Another item needed for the autopilot system was the Raymarine EV-1 sensor core. This is a solid state 9 position sensor including heading, roll, pitch and yaw for the autopilot to let it know the boats orientation to the world.

This sensor is connected to and powered by the ACU400 through the NMEA 2000 network.  It can be found online for about $500.

We selected the Raymarine P70s for the auto pilot control head. This one is often used in sailboat configurations. The autopilot control head is the main interface to the autopilot. It was connected to our new NMEA 2000 network which also powers the unit. The Raymarine Axiom chart plotter can also be used to control the autopilot.

The control head has buttons for turning the autopilot on and off and adjusting the course of the boat. If a wind instrument is installed it can also be set to keep a course compared to the wind. These are for sale between $450-500 on line.


The Raymarine Type 2 hydraulic pump was needed for our larger boat. It is electrically connected to and controlled by the ACU400.  The pump will handle cylinders from 14-21 cubic inches. This pairs nicely with our Teleflex hydraulic cylinder which is 18.9 cubic inches. The autopilot drives the pump in either direction to move the cylinder in or out to steer the boat.

There are three hydraulic hose connections on the pump. The left and right connections are connected in parallel with the main lines to the cylinder and the pilothouse steering pump. The center connection is connected to a third hose that goes back to the pilothouse steering pump reservoir overflow.  These pumps can be purchased online for $750.


The last piece of the autopilot system is the Rudder Angle Sensor.
This is attached mechanically to the rudder quadrant.  It electrically provides feedback to the autopilot unit on the angle of the rudder.  These can be purchased for $210 from several places online.

We set up a new Raymarine NMEA 2000 network to allow all of the new equipment to talk to each other. NMEA 2000 is the newest communication protocols which is standardized now between all major marine manufacturers. The diagram below shows how we connected the devices into the network. We did power the network from the Raymarine ACU400. It shows that it could also be powered with a power cable at any point in the system. It is best to power the network in the middle if you can to spread the loading. We purchased the Raymarine NMEA 2000 starter kit and some additional cables and connections for about $200.

NMEA 2000 is a simple plug and play system which makes it easy for the new generation of marine electronics to communicate efficiently.

I hope this post help others who may be struggling with how to integrate two types of steering systems with an auto pilot. It takes a bit of design to get it all to work but we are happy with the results.

That about wraps up our steering system rebuild. It is more complicated because of having both mechanical and hydraulic steering. I guess we could have went with an all hydraulic system but we never considered that.

The advantage of having two systems is that we can always run on autopilot or hydraulic steering if our mechanical cable steering system fails.

***Sail On***/)
Mark






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