[NorCalBoater]

I just saw the other post on the Simrad AP issues but mine seem a bit different.

On my 50' Kha Shing the PO had a full RayMarine Electronics package installed about 4 years ago. The system includes C120, open array 24 mile radar, GPS, Navionics Platinum, AIS and the ST8001 auto pilot. All of this is at both stations. From the invoices and all of the bells and whistles he did not go cheap.

The problem is that when I go from Standby to Auto on the AP I get a 3 second message that says "No Rudder Data." That flashes off and the AP takes over. But then the boat begins to yaw back and forth in increasingly larger arcs until I switch back to Standby.

While in Standby the heding may indicate the actual heading but rarely. And it never holds. It is always moving and changing even if I am holding a steady course.

I've looked at the manuals and gone through the setup and compass calibration but I know I am doing somthing wrong. I believe the system has a fluxgate compass but can it also get heading info from the GPS?

What am I missing?

Thanks,
Shawn

[K1W1]

Hi,

No Rudder Data would indicate that the system is lacking some information as to where the rudder is.

Do you have a Rudder Angle Indicator?

If so is it working and is it the same unit that drives the AP?

A digital heading display can wobble around a bit even if there is no discernible change in heading.

[61c40]

There should be a feedback potentiometer that gives the control unit a referance as to the rudders position. ( a rudder angle indicator combined or seperate unit at the rudder post) Do you have a RATE & GAIN control on that model? I'm not familiar wih that specific model but if you do check your settings that control how much rudder is applied! The settings for a following sea are much different than a head sea.

[CR CRUISER]

The autopilot gets its rudder angle data from a rudder angle sending unit which should be located in the vicinity of the rudder quadrant. I assume that you have shafts as opposed to stern drives. It could be as simple as the link rod has come loose between the sender and the rudder. When in standby, does the rudder angle indicator move in relationship to the rudder when turning the wheel? If not then you have an issue with the rudder sender.

The heading is obtained from the fluxgate compass which should be located midship and relatively low. However, I've seen them put just about anywhere. The autopilot does not get it's heading from the GPS heading.

I'm thinking that you have 2 separate issues happening and maybe a third. Depending on which main autopilot control board you have, there may be a hardware and possibly a software problem as well. There were a number of software updates for the S1G and S2G control boards as well as a service bulletin pertaining to a capacitor installed backwards in the processor.

I would suggest that you get a Raymarine tech to look at the system and determine what needs to be done.

[rcrapps]

So, is this a new problem or you have lived with it for four years? What mods or work have you had to your boat just before it stopped working correctly (assuming it's a new failure)?

[NorCalBoater]

I just bought the boat a couple of months ago. the autopilot worked during survey. It would not work when I picked the boat up and hasn't worked since. I have made no modifications or alterations to the electronics.

[Pascal]

Start with the sending unit at the rudder post. Note that some boats have a separate rudder indicator dial which may have it s own sender. Does the rudder indication on the AP panel work?

I ve always seen the AP digital heading to be rock solid but start with the rudder sender

[rcrapps]

from the manual;

When holding a constant course
in STANDBY mode, the heading
continuously changes:

The Autopilot is connected to a Raymarine Pathfinder
unit with the “Bridge NMEA Heading” option switched
on. Disable this feature on the Pathfinder unit.

Pretty sure the C series had this also.


And it says No Data or No rudder data?
"No Data" is the usual syntax that can include a few communication issues including rudder.
Resolve your data loop (above) and your problems should go away. Or it's time to call in a tech. Good luck, please let us know what you find.