How sensitive to wiring and electronics is a gyro sensor for autopilot?

[davethedog]

Hello all,

currently have a Raymarine S3 autopilot with a raymarine fluxgate compass. Just purchased a Seymo gyro add on for the S3 computer and I know that ideally it should be away for all wiring, electronics etc but how important is that?

Reason being is I have found a great installation location, but it is next to a Raymarine RN300 GPS display and the associated wiring.

So, would that work or am I better extending the wiring and running yet more cables (a pain) and putting it further away?

Thanks

DTD

[sailorboy1]

pretty important for the heading compass to be away from other sources of electrical and magnetic interference. Far as everything else, my cables are in same conduits as other stuff and it has never been a problem.

Now a funny story about the heading compass. Mine is installed in the galley in the space where the trash can is. Which means it is also under a counter space. One day on a crossing I needed to work on a macerator pump. We were out in the open with the autopilot steering and my wife in the cockpit. I go down and pull out the macerator pump and sit it down on the counter above where the heading compass is. Next thing I hear is my wife yelling that the autopilot is turning us around. Because the magnetics in the macerator motor changed our sensed heading even though it was 2' feet away from the heading sensor.

[davethedog]

yes, think i may just do the painful route of mounting it in the centre of the boat by the trash can just in case.

DTD

[GordMay]

Is the 'Seymo gyro add on' a gyrocompass?
A Gyrocompass makes use of a continuously driven gyroscope, to accurately seek the direction of true (geographic) north. It operates by seeking an equilibrium direction, under the combined effects of the force of gravity, and the daily rotation of Earth.
As such, it is immune to magnetic interferences such as those caused by ore deposits, steel structures, or electric circuits.

[davethedog]

Originally Posted by GordMay

Is the 'Seymo gyro add on' a gyrocompass?
A Gyrocompass makes use of a continuously driven gyroscope, to accurately seek the direction of true (geographic) north. It operates by seeking an equilibrium direction, under the combined effects of the force of gravity, and the daily rotation of Earth.
As such, it is immune to magnetic interferences such as those caused by ore deposits, steel structures, or electric circuits.

It is this one I am fitting soon:

https://seymonautica.com/en/categori...lot-v-205.html

DTD

[GordMay]

Originally Posted by davethedog

It is this one I am fitting soon:

https://seymonautica.com/en/categori...lot-v-205.html

DTD

The Seymo gyro autopilot V 2.05 description says: “The instrument of this inertial guidance system includes gyroscopes and accelerometer.”
So, I would say it’s not subject to electrical/magnetic interferrence.

[Frankly]

A carpenters plumb bob could qualify as an inertial navigation system based on modern ad BS.

If this add on is just 3 axis rate sensors and 3 axis accelerometers (to sort out the actual horizontal angular rate), then mount it where most convenient.

One little test I ran on my old Raymarine X-5 (had the rate sensor built in) was to rotate the fluxgate 90 degrees and watch the display. Took 30 to 60 seconds for the display to register new heading. Rotated the power unit (with the rate sensor) 90 degrees and the new heading response was immediate. I take from that, that short time heading was heavily weighted from integrating the yaw rate sensor and long term heading was weighted from the fluxgate to compensate for the integration error that creeps in from the rate sensor. Your add on sensor might not be so tightly integrated to the RM AP processing.


Frankly

[sailorboy1]

Originally Posted by davethedog

yes, think i may just do the painful route of mounting it in the centre of the boat by the trash can just in case.

DTD

Why is it painful?

Or are you saying for me never to try to help answer your question again?

[AndyEss]

Is the output of your gyro analog or digital?

If analog, using shielded cable with twisted pair conductors might be advisable. And keep the cable as short as possible.
If it has digital output, do as you will.
Modern low cost gyro’s and accelerometers are based on silicon MEMS technology which is relatively immune to low level magnetic fields.

[OS2Dude]

The description page states it is an interial gyroscope, and imediatly tells the autopilot computer how far off course a wave or gust may have blown your boat. As stated above, a mechanical gyro is not subject to magnetic fields like a compass can be.

[CarinaPDX]

While the gyro you intend to install should not be affected by magnetism, and should improve the AP course steering, it is not the way I went or recommend. The old RM/Autohelm units use a pretty crude fluxgate compass and benefit from an upgrade to an electronic compass. The best solution is to buy a proper electronic compass with gyro and accelerometer, connected with either NMEA 2000 or 0183, and disconnect the old fluxgate compass.

Greg

[davethedog]

Originally Posted by sailorboy1

Why is it painful?

Or are you saying for me never to try to help answer your question again?

I was referring to the fact that if I have to mount it away from any electronics etc it will be painful as would have to extend the 3 core wiring and run it through some shitty routing to get to the course computer.

[davethedog]

Originally Posted by CarinaPDX

While the gyro you intend to install should not be affected by magnetism, and should improve the AP course steering, it is not the way I went or recommend. The old RM/Autohelm units use a pretty crude fluxgate compass and benefit from an upgrade to an electronic compass. The best solution is to buy a proper electronic compass with gyro and accelerometer, connected with either NMEA 2000 or 0183, and disconnect the old fluxgate compass.

Greg

Agreed, but did not want to spend too much (as in the future may well upgrade to the new EVO AP system anyway).