Heading off - Old Autohelm / Raymarine setup

[Tim Good]

I have a system which comprises of older Autohelm systems and the occasional slightly later Raymarine unit.

A gyro was added to the system in around 2003 along with the Autohelm fluxgate compass. I’ve tested the compass as I have two and they’re ok. I’m assuming the gyro is ok.

In this diagram you can see the gyro sends A signal to the course computer but also the outside helm. When I disconnect the gyro from course computer I still get a heading on my instruments.

What I can’t determine is how the digital from the gyro is integrated into the ready of the system. It’s not going into the back of the ST60 wind or St7000. Where else might it be integrating into the system in order to feed the heading to the ST7000 and the E80 plotter?

The reason I’m asking is because my heading is off significantly so I’m trying to track down all connections to ensure they’re not loose or corroded.

 

[geem]

When my heading was off considerably, it was a fault in the course computer. I tried swapping fluxgate compasses but that didn't fix it. My gyro was built in to the course computer. I am never sure it really did much. My spare course computer didn't have the gyro and I could never see the difference in how the autopilot behaved. With the new ACU400 and EV 9 axis sensor, it's a different world

 

[Tim Good]

Hmm ok. It would be easy enough for me to bypass the gyro and see if that’s the issue. Thing is I had this problem several years ago and it fixed itself when I went poking around. So I’m fairly convinced it isn’t the gyro. That said I have a spare course computer so I could try that

 

[geem]

Hmm ok. It would be easy enough for me to bypass the gyro and see if that’s the issue. Thing is I had this problem several years ago and it fixed itself when I went poking around. So I’m fairly convinced it isn’t the gyro. That said I have a spare course computer so I could try that

Worth a punt. Always good diagnostics if you can swap stuff out to see if it fixes it

 

[sealutions]

The gyro is connected to the Type 300 course computer which is in turn connected to the ST7000 over the Seatalk network. However it's the fluxgate compass that is providing the heading not the gyro (the gryo is helping the course computer make calculations in combination with the fluxgate by giving it the rate of turn and roll).

Your E80 will be getting heading data from the fluxgate via the autopilot or another heading source on the network.

You say you have two fluxgates, are these both on the network or is one just a spare?

More often that not, if the heading is a long way out, it's something magnetic in close proximity to the fluxgate. Make sure that no tool boxes, portable radios or other magnetic or ferrous metals stored close by.

If in doubt try temporarily moving the fluxgate to a different location.

 

[Tim Good]

Th

The gyro is connected to the Type 300 course computer which is in turn connected to the ST7000 over the Seatalk network. However it's the fluxgate compass that is providing the heading not the gyro (the gryo is helping the course computer make calculations in combination with the fluxgate by giving it the rate of turn and roll).

Your E80 will be getting heading data from the fluxgate via the autopilot or another heading source on the network.

You say you have two fluxgates, are these both on the network or is one just a spare?

More often that not, if the heading is a long way out, it's something magnetic in close proximity to the fluxgate. Make sure that no tool boxes, portable radios or other magnetic or ferrous metals stored close by.

If in doubt try temporarily moving the fluxgate to a different location.

Thanks.

My second compass is a spare so I changed one for the other to check. I then moved it around to rule out magnetic interference.

 

[Concerto]

More often that not, if the heading is a long way out, it's something magnetic in close proximity to the fluxgate. Make sure that no tool boxes, portable radios or other magnetic or ferrous metals stored close by.

If in doubt try temporarily moving the fluxgate to a different location.

Finding what causes the autopilot to malfunction can take time to solve. I had a problem with mine and finally tracked it down. This short video shows what caused the problem, so I knew what had to be done to solve the problem.