Our Two Autopilots Setup

Introduction

On our Saba 50 the steering system is a hydraulic system. The steering wheel operates a hydraulic pump, which itself operates a hydraulic cylinder (See Image 1 below) which pushes and pulls on the starboard rudder stock arm (Image 2 below). Note that we need to add a Rose Joint to this arrangement as the board that it is mounted on flexes and we are finding that the stainless steel bolt though the aluminium arm is leaving filings as it turns. John previously pointed out this problem to us and its on our jobs list.

The starboard rudder is operated by the hydraulic cylinder and the port rudder is linked by a aluminium bar that joins both rudders together so that they move in unison.

We ordered the Garmin autopilot from FP and this works with a hydraulic pump (Image 3 below), which is installed on the hydraulic circuit of the helm system.

The autopilot pump will turn the rudders in either direction , and works in a similar fashion to the hydraulic steering that is driven from the steering wheel.

It is important to note that if either the hydraulic pump for the steering fails (see Image 1 above), then we also cannot steer the boat with the autopilot either. FP provides emergency steering for the Saba that you have to stand in the engine room to try and use. Totally impractical.

So not only did we need a second autopilot in case our primary autopilot failed, we also needed one in case our hydraulic steering failed.

Our Solution

Uchimata installed a Leroy and Smitt (L&S) cylinder (See Image 4 below) and a hydraulic pump (Image 5) on the bit arm of the port rudder. Our primary autopilot on La Mischief was also a L&S hydraulic system and we were very comfortable with this. We also kept hold of the maintenance kit, which is a bit of a bonus.

The operating principle is the same as for the main autopilot, but is independent of the helm steering system, thereby providing redundancy for this system also. We can throw away our emergency steering system (but haven’t). The L&S autopilot cylinder directly actuates the port rudder, with the starboard rudder being actuated by the aluminium bar linking the two rudders together.

To reiterate, we can now have a hydraulic break in our boat’s helm system, the steering wheel pump, the helm system cylinder or the main autopilot’s hydraulic system pump, and we can still steer the boat as the port system is completely independent.

Each autopilot has its own head, and each are equipped with feedback (Images 6 and 7 below), there is one for the main pilot on starboard and there is one for the second pilot on port. So no matter which autopilot we are running, we can always tell where the rudders are.

The Second Autopilot

Now we have 2 autopilots on board, w must be extremely careful that we don’t have both on at the same time. This could be quite catastrophic.

Unlike boats with mechanical steering, on our Saba with its hydraulic steering the autopilot pump (See Image 3 above) is mounted on the hydraulic circuit and “closes” the system, meaning the steering wheel is effectively disconnected whilst the autopilot is engaged. Disengaging the autopilot “opens” the hydraulic circuit and allows the steering wheel to once again be engaged. Therefore to use the second autopilot we must also do this but manually by turning a ball valve to cut the pressure to the ram. This is the same ball valve that was installed to allow the emergency steering bar to be used.

When the second autopilot is used, the bypass valve (08) must be opened.

Whenever the bypass valve (Image 8 above) has been opened and then closed, its very important that you use the feedback (Images 6 and 7) to ensure that the rudders are in the axis of the boat.

Step By Step Guide to Using the Second Autopilot

1. Make sure the rudders are centred using the feedback on the Autopilot Head.
2. Make sure the main pilot is on stand-by.
3. Power on the second port autopilot by setting the switch ( Image 9 Below) on the second pilot.

4. Open the bypass valve (see Image 8 above) and simultaneously set the second autopilot to AUTO (Head unit is under winch).

At this point, the second autopilot will be steering the boat. Its important to note that manual steering is unavailable when this second autopilot is being used.

Moving Back to the Primary Autopilot

1. Make sure the rudders are centred using the feedback (see Images 6 and 7 above) that displays on the Autopilot Heads. This is very important.
2. Make sure the secondary pilot is on standby.
3. Power on the primary autopilot by setting the Power Switch (see Image 9 above) to the primary autopilot.
4. Close the bypass valve
5. Set the Primary Autopilot to Auto.
6. Test that the Steering works by disengaging the autopilot briefly to test.

The first time we tried it, it didn’t work. We had Sopromar in Lagos look at it and they set the “Drive Unit Class” to Solenoid and Voila!, we got power to the ram and it started working.