Raymarine Autopilot not engaging

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Mikehp0

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I wonder if anyone can give me any general advice on this, please? My 2008 Prestige 38s, Zen Dog, has Bravo 3 outdrives with the original Raymarine autopilot hooked up to an ST6002 head unit then interfaced into a 2015 Raymarine ES128 chartplotter.

The autopilot doesn't seem to engage. Previously, pressing AUTO would load up the hydraulic steering and the boat would follow a bearing. I could watch the drives being moved to port or starboard by themselves to compensate for wind, tide etc on the ST6002. Similarly, TRACK would follow routes set on the plotter.

Now, pressing AUTO has no effect. There's no load applied to the helm and the boat will gently veer off course. The ST6002 and the analogue drive angle indicator both correctly show the position of the drives. Changing the course on the ST6002 (by pressing +10 or -10) has no effect. No error messages are displayed.

The boat was out of the water for a drive leg and engine service. This issue was spotted on the first sea trial following her relaunch.

I've generally picked up my basic boat maintenance and repair knowledge as a consequence of being forced to fix things that have broken. Autopilots are not something I've had to worry about on this boat or its predecessor. They've always just worked. As a result, I don't really know what I'm looking for... Is there likely to be a mechanic actuator or does it work on the same hydraulics as the steering?

I'm going to visit the boat tomorrow so any help would be gratefully received.

Many thanks!
 
Mike,

On my old sailing boat our Raymarine AP with the same ST head packed it in and the boat wouldn't track or hold a head, but just starting turning in circles.

The fault was the rudder sensor. You can check the rudder sensor output with a multimeter - here is alink Rudder Reference Test

I hope this is 'good gen'!
 
mcanderson said:
Mike,

On my old sailing boat our Raymarine AP with the same ST head packed it in and the boat wouldn't track or hold a head, but just starting turning in circles.

The fault was the rudder sensor. You can check the rudder sensor output with a multimeter - here is alink Rudder Reference Test

I hope this is 'good gen'!
Click to expand...
Many thanks for this!

I'm pretty sure the rudder sensor (or whatever it is called with outdrives and no rudders!) is OK - the ST6002 shows the "rudder" angles correctly. I know there's a mechanical linkage from the steering arm to the "rudder angle sensor" because it came undone once.

I still need to understand how the autopilot actually steers the outdrives - will have a good look and take photos later!
 
In the aviation world we would call it a SSLG (a suitable series of linkages and gears). Well that what was taught to me on my instructors course and I have use for many years to explain the complexity of military helicopter autopilots to great success!
 
Check the fuses inside the Auto pilot course computer, you could have lost power to the hydraulic pump, or the pump is faulty. You will have a pump plumbed into the hydraulic steering somewhere in the engine room, it should have 3 hoses going to it,
 
There are two types of auto pilot hydraulic pump, the most common is on demand which runs either one way or the other from two wires from the course computer which reverses the polarity depending on the command to steer port or starboard. The other is a continously running pump which had two solenoid valves controlled by the course computer which direct hydraulic pressure to one side or the other of the hydraulic steering system. Both these systems are T’d into the low pressure hydraulic system from the helm pump, so it over rides the normal steering when activated. It sounds like the pump isn’t working for some reason.
 
General info on " type 2 " DC driven hydraulic pumps : You can apply power directly to the pump from a high current ( fused) test cable from the battery. Reversing the polarity will change direction. Be careful that you are watching the rudder or stern gear as there is no end stop limit apart from you removing the power.I did this to my system that has sat idle for years ( auto helm wires disconnected by previous owner) , running full steering swings port to starboard and back a few times to clear I suspect air in the system. I also noticed there is a steering fluid reservoir tank with a bicycle valve on the top and a pressure gauge. This needs a few psi (5 to 10) to keep the system low pressured; don't go mad as you will potentially cause fluid to leak from old but normally serviceable system ( I did!).
 
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