Garmin Auto Pilot makes tug go into tight 360 circles.

[Skeeter]

Coming back from a 6 mile open water trip the boat (2012 R27) suddenly veered left on auto pilot. Putting it back on standby and slowing down, it was engaged again. The boat went into tight 360 degree turns. Tried a second time and same result. Checked the bolt that ties the rudder to the auto pilot arm and it was fine. Not familiar with the auto pilot components. Any hints as to what has gone wrong. We have put 1k nautical miles on this boat with not previous problems.

 

[scross]

That behavior is exactly what happens, and is suppose to happen, when the Man Overboard on the Garmin is triggered. It’s called a Williamson maneuver. Perhaps a MOB button is sticking if you have one, the MOB tab on the Chartplotter menu was accidentally pressed or a waypoint has been inadvertently designated as a MOB point.
Per the Garmin manual:
“The Man-Overboard (MOB) function is a common feature for Marine GPS units. When the MOB button is pressed, the GPS automatically marks a waypoint at the current location and allows you to enable a "Go-To" navigation line to take you back to the initiated MOB location.
If the GPS device is connected to a Garmin autopilot using NMEA 2000, the GPS device will present a prompt to enable the autopilot. If the autopilot is enabled, it will force the boat to perform a Williamson maneuver to return to the location of where the MOB was initiated.”

PS: This behavior can also be triggered by selecting Pattern Steering from the GHC10 or GHC20 autopilot menu. If that is the trigger, there are a number of steering patterns that could result - everything from zig zag to lazy circles to a Williamson turn.

 

[Baetz]

I have had the same thing happen and agree with scross above. I studied the auto pilot manual and was able to understand the layered function they have in the autopilot, there is quite a bit of function available. I would not say either the manual or the device was all that clear and straightforward.

 

[Skeeter]

Makes sense. My wife was at the controls so was not privy to what she was doing. Thought it might be a seal on the port side of the hydraulic unit for the Auto Pilot. Thanks again for the quick response.

 

[Red Raven]

In addition to the MOB cause it is really easy to mistakenly engage the circle pattern used for fishing. On our 2014 systems you can engage the autopilot to “Follow Route” on either the Garmin or the autopilot controller. If I do not initially engage the route on the Garmin I have to use the menu button on the AP display. For some reason I have never figured out, the “Follow Route” option is not always available. In its place is the “Circle Pattern” (or similar name) option! Don’t know how many times I have (or was about to) pressed that button!

 

[Submariner]

In addition to the MOB cause it is really easy to mistakenly engage the circle pattern used for fishing. On our 2014 systems you can engage the autopilot to “Follow Route” on either the Garmin or the autopilot controller. If I do not initially engage the route on the Garmin I have to use the menu button on the AP display. For some reason I have never figured out, the “Follow Route” option is not always available. In its place is the “Circle Pattern” (or similar name) option! Don’t know how many times I have (or was about to) pressed that button!

What I've learned is, when I create the route on the chart plotter, it'll ask me if I should engage the autopilot. If I say no, then I wouldn't get the "follow route" option on the autopilot. Often, when I plot my course I am not in a position to actually engage the autopilot.

What I have trained myself to do, which works every time... I plot my course on the chart plotter, it says "do you want to engage the autopilot", I always click "engage", then I immediately press "standby" on the autopilot display. Then I motor around until I get to the point I want to engage the autopilot and simply press the "follow route".

 

[Red Raven]

In addition to the MOB cause it is really easy to mistakenly engage the circle pattern used for fishing. On our 2014 systems you can engage the autopilot to “Follow Route” on either the Garmin or the autopilot controller. If I do not initially engage the route on the Garmin I have to use the menu button on the AP display. For some reason I have never figured out, the “Follow Route” option is not always available. In its place is the “Circle Pattern” (or similar name) option! Don’t know how many times I have (or was about to) pressed that button!

What I've learned is, when I create the route on the chart plotter, it'll ask me if I should engage the autopilot. If I say no, then I wouldn't get the "follow route" option on the autopilot. Often, when I plot my course I am not in a position to actually engage the autopilot.

What I have trained myself to do, which works every time... I plot my course on the chart plotter, it says "do you want to engage the autopilot", I always click "engage", then I immediately press "standby" on the autopilot display. Then I motor around until I get to the point I want to engage the autopilot and simply press the "follow route".

Ha! That is exactly what I do now as well! Create route, Engage, immediately press Standby, review the route, drive back to the route or recalculate route, then press Follow Route.

The part I don’t understand is why the AP loses the Follow Route option sometimes if you don’t immediately engage. The route (magenta line) is still there but “Follow Route” is replaced with “Circle Pattern”. I don’t believe this always happens but I agree the fix described always works. Took me a while to learn to always press Engage and then Standby first. Perhaps this is what the OP encountered.

Funny how we learn the work-around to make the system behave!

 

[Skeeter]

Went on a 7 day trip and checked the Way Points on the Garmin 7600 to see if there were any MOB waypoints, none. Checked the GHC 10 and it was not engaged in any circle paterns, fishing paterns or MOB paterns. Will look at recommendations above. Found another Tug that has the same problem with autopilot and had not come up with a solution. We normally just set the autopilot on a compass bearing rather than a route. So will see if engage and standby then engage will work.

 

[SJI Sailor]

Everyone differs on AP, but two things I do are:

1. Never plot the course until I'm out of the marina. That is because I once had AP engage for an unknown reason in the middle of navigating tight quarters and fought me until I realized what was happening. The OP issue could be similar.

2. I never let it follow the course it plots. Instead I control the heading myself either to follow it or (more commonly) follow some approximately parallel course. The plotted course is just a reference. (In aviation this is called SLOP, "strategic lateral offset procedure".) I do this both to be in control and choose waters I prefer, and because I sometimes see it chart routes that cut corners of buoys I don't want to cut, and similar things.

 

[knotflying]

Did you try resetting the unit? I would disconnect the wires going to the autopilot and remove the fuse as well. Reconnect everything and see what happens. If all fails then a call to Garmin may be in order.

 

[BGW]

That happens to me from time to time. If I’m making a turn in standby mode and hit engage it continues the turn without holding course or even makes a tighter turn. It’s usually when I’m trolling and making a tight, hurried maneuver which makes it even more irritating.

Generally I find I have to have the boat and rudder well centered before I engage the autopilot. If I’m turning and try to hit engage when I get to the heading I want it won’t hold. It did when the boat was newer but not now.

 

[Skeeter]

After about 50km of additional boating the chart plotter finally signaled a message from the auto pilot saying it was "totally disengaged and not working". Will have to check with Garmin to see what would trigger this message and what unit is failing. Checked all the wires and everything was connected properly.

 

[sgeary]

If you want to return to Follow Route and it is not at the top of the autopilot page, scroll down to GPS Steering and select that. Follow Route will be the first option.

 

[Skeeter]

Reset the GHC10 left and center button when unit is turned off then on. It took about 30 seconds and GHC10 responded with a "connected to chart plotter" message. Engaged auto pilot and it turned the boat to starboard instead of following the current bearing. Previously it would turn to port. Will try disconnecting unit next summer.

 

[strangecrew]

It's all about whether you've engaged follow-route on this specific route before or not. If you've not engaged the follow-route mode via the garmin yet, the option won't be present in the auto-pilot display at that top position. The top position will be occupied by the circle option. Instead, you can engage by scrolling down to 'GPS steering' in the same menu. Once you've done this, you can go to standby at any point and the engage route option will occupy the top position of the menu again.

I too have have punched into the auto-pilot what i thought was going to be a follow-route only to end up in a circle....

 

[Skeeter]

Figured out what was happening. The auto pilot has several modes. One is "Pattern" and one is "Steering". My wife was selecting "Steering", but failing to go to the bottom of the screen where there is a "Select" button that maintains your selection, otherwise, it was defaulting back to "Pattern" mode.

 

[irwinengineering]

Hi,

I'm glad that you got this sorted out. I had a similar issue with a different "fix".

After having issues with the system not finding the controller and/or very long startup periods, I separated all cable connectors and sprayed liberally with contact cleaner. Then mated/de-mated several times to scrub the electrical contacts clean(er). This helped quite a bit with the startup time.

On a test ride, I engaged heading hold. It all seemed fine for a minute or so and then the boat turned hard to starboard. I shut down and restarted the system and tried again, same result. Everything had been fine for the last five years with this system, the only issue being the initial startups. Very frustrating.

Back at the dock for some diagnosis, I stood at the stern so that I could watch the rudder as I keyed the Garmin remote. If I commanded a turn to port, the rudder would respond with a starboard turn and vice versa. Weird, it had never done this before. Looking at the GHC10 screen more closely, I noticed "REV" in the upper right corner. I had not noticed this before, maybe software rev??

Off to the Garmin manual - page 4, Direction Control, there's a button on the screen marked DIRECTION. Press this and you reverse the action of the autopilot. Not sure why anyone would want this function, certainly not so easy to access. I pressed the button and the REV went away and the autopilot went back to correct behavior. Amazing.

fair seas,
Brendan

 

[irwinengineering]

There also seems to be some discussion on abrupt turning behavior of the GHC when engaging routing. Here is what I have learned:

If I am on a route-to with the autopilot and go to standby for a manual avoidance maneuver, when I reengage the autopilot the initial steering reaction can be quite alarming. At first this seems to be some mental issue with the Garmin, however it is not. What happens is that the Garmin calculates the route when it is first established. It then tracks any deviation from the route and attempts to correct. When engaged, this is generally done through minor steering inputs and all is good. When put in standby, it does not recompute the route but does continue to track the deviation. As the deviation grows, so does the resultant steering input for correction. So, when you steer away from the route and then reengage the autopilot, it wants to get back on the route as quickly as possible. This can result in a very aggressive turn, depending on how far off track you have steered it manually.

Be extremely cautious reengaging autopilot when other boats are around. I have taken to manually steering back to the route before reengaging, I get a lot less stink-eye from the commander that way.

be safe,
Brendan