Autopilot Feedback And Sensitivity

Your looking for the manual response setting.
I'll get back to my desk tonight and update ya tonight.

Question for my notes,, when you commissioned the AP, after you turned the boat in circles to setup the compass,, you let the AP go thru a checkout and first learning cycle,, was it a calm day? And the routeen completed with no errors?

Agreed, I also wouldn't like that, and I think that there must be a way to correct that behavior.
But I'm afraid I can't be specific because I'm not familiar with Simrad APs.
In Furunos for instance, I'm pretty sure that there's a specific setting for addressing this condition.
IIRC, it's buried inside the so called "technician mode", which is supposed to access those parameters that should be fine tuned upon commissioning, and then never touched again.
Anyway, the way Furuno call this parameter is "rudder dead band", and it's specifically meant to reduce rudder hunting.
It does that by defining a course deviation in degrees which the AP consider a dead band, making course corrections only when the course deviation exceeds that limit.
It can be set from zero to plus/minus a few degrees (3, as I recall), in steps of 0.5 degree.

If you are experiencing rudder hunting even when cruising in calm waters, and with the boat keeping a straight course, I suppose that even a very narrow dead band (say +/- half a degree, or one degree max) should be enough to cure the problem.
But as I said, I can't tell you how to set that on Simrad APs - and neither if it's possible at all, though I'd expect all APs to allow this type of tuning, in principle...

There is a way to change the response rate, but I can't remember the exact sequence to get to it. I believe the autopilot has to be in auto mode, then you press menu twice really quickly, that gets you to a menu where you can change the response rate.

No you can change the response RATE, not between low and high.....that's done by hitting auto twice.......You have to get into the second menu in order to do it.......I think autopilot needs to be in auto mode (might be in standby, it's been a while), then hit menu quickly twice, should bring you into a setup menu......in there.

"To adjust the response level of the autopilot, access the Autopilot Settings menu, locate the Response Level option, and select the desired level based on your vessel's handling characteristics and sea conditions."

See page 21 "RESPONSE ADJUST"
ap28opman.pdf (psicompany.com)

I believe response rate is a much more basic parameter, mostly meant to adapt the AP reactivity to sea state.
What DM is experiencing, as I understand, is what is typically referred to as rudder hunting, and can only be avoided by setting a dead band.
Which can be very narrow (like half a degree), but if there's none at all, THAT is the culprit of rudder constantly hunting back and forth, not the response rate.
Mind, that can well be a dealer calibration, to be done upon commissioning - not sure of how it works on Simrad APs.
@DM: looking forward to hearing what Simrad tech support will tell you, after you'll talk to them.

In the old days it was called Gain.
Now Response.
And other fine tune settings.

Attached are pages from my AP28 manual.

Auto high / low means the two different, preset responses settings can be used pending hull speed.
Each of these two (High / Low) settings contain it's own response (gain) parameter. Auto, then 1 thru 9.
You can manually change these values to improve over the auto settings.

I had an AP28 / AC20 on our Bertram for many years. Drew a perfect straight line.

Free PDF readers don't edit or cut/paste. Sorry not pretty & includes snailbote stuff.

If the response rate is too high, the autopilot will do EXACTLY what the OP is experiencing because it's over steering. Over steers one way, over shoots the degree it's supposed to be at, oversteers back the other way, over shooting the compass the degree it's supposed to be at, and on and on...... I know what I speak and I posted the correct link with the page number in the SIMRAD owners manual to fix his problem.

Speaking of AP setup, how good is Simrad Virtual Rudder feedback vs a physical rudder position sensor ?

my new AP has VRF has default and i m wondering if installing a sensor would make improve results.

Hard wired feedback is preferred.
The AP computer knows where the rudders are and how much rudder to apply.
The AP computer knows where the rudders are and knows when to stop,, before the rudders and/or cylinders hit their travel stop.
I think it is faster.
I always felt Virtual Rudder was an emergency mode.

I missed your post with the link.
Yes, to much response (gain) will make S curves.

Reducing the response a notch may help this.
Reducing to much can also cause more hunting of the base line.

But there will always be a lil wonder and rudder movement (dead band).
It's how APs work.
There is always a micro adjustment for the AP to make.
There is always a micro adjustment that bumps the rudders.

There are other adjustment to make (counter rudder, trim) including slowing down the pump flow.
Some pumps allow this.

Question; Any slop in the rudder feedback linkage?

I installed a physical Simrad rudder feedback sensor (N2K) on my new Simrad and tried it for the first time tonight. What a difference. The boat tracks straight whereas without it using the Virtual Rudder Feedback, it was all over the place. I don’t even know why Simrad bothers with the virtual feedback.

it was worth the hassle of running the N2K backbone all the way to the stern.