Autopilot

[davecook]

I don 't know if it's my imagination or ? the trip to the north channel we just finished had my autopilot ( GHC 10 and Garmin 7212 chartplotter ) doing extreme turns to start a heading and took a long time to get on course ( from 300 ft left or right to within 10 -20 ft ) . Weather was not rough or windy . I had a look at the manual , but nothing jumped out at me ( but i am , electrically and computer challenged ! ) I do want to get a I pad for a backup chartplotter . any ideas on these matters ? thanks Dave

 

[knotflying]

Dave,
Can you give a little more detail of the symptoms? Your explanation sounds a little contradictory. If it is making an extreme turn to a waypoint then why is it taking a long time to get on course? In any event did you try a complete reboot? Disconnect the wires from the back and then plug them back in. Sometimes that cures many problems. When you are not following a route, is the autopilot responsive to manual inputs?

 

[Scuffy]

I would wonder what was your boats speed when you engaged the autopilot?

 

[CAPTCRUNCH]

If the OP's experience is like mine, the boat sometimes makes a big, dramatic turn AWAY FROM the target when I select "Engage Autohelm" (or similar) after selecting "Go To" on the chartplotter. The display tells me I'm already 300 feet off the track, and the cross-track error usually increases for a while before the boat gradually comes back to and stays on the original track. This initial hunting behavior usually stays on one side of the track without swinging across it. I don't recall that boat speed makes much difference. It might be my imagination, but this routine has been less noticeable since I did the "Dealer Configuration" (or similar) on the autohelm. I too had originally thought I could adjust the gain or sensitivity on the GPS but don't see anything like that in the literature. At its worst, I was in the habit of alerting the crew to hold on to their wine glasses before I pushed the button.

 

[davecook]

Speed is aprox 8 knots , have not tried manual steering adjustment with the autopilot ( is that the 1 to 15 soft keys on the left and right ? ) have not tried to reboot , will save that for last thing . I always steer course before i engage autopilot , it is pretty much on track before i hit the button to engage , then it does a hard turn or two , and ends up 200 or 300 ft to port usually , and spends a long time to get to 10 or 15 ft from on course . thanks Dave

 

[CAPTCRUNCH]

I think I would consider doing the Dealer Configuration on the autohelm. It's just conjecture, but I think part of that process teaches the autohelm how much to turn the rudder to get a certain change of course in a certain amount of time at a given boat speed. If so, a poorly educated autohelm might be responsible for the tracking drama we're talking about.

 

[baz]

Are you employing the AP to...

1) Follow a specific Heading ?

or

2) To follow a Computed safe course to some destination ?

In the past (see http://www.tugnuts.com/viewtopic.php?f=5&t=556&p=4367&hilit=Shadow+drive#p4367) when I had AP issues I contacted the following person at Garmin Tech Help. Robert was excellent and actually flew up from a Brazilian appointment to help me solve things on the water for around 4 hrs of his time. He and Garmin's AP software guru in Europe sorted this out after a bit of fiddling around. The AP software is very sophisticated.

Call and chat with Robert.

Robert Archer (Garmin Tech Help)
541-207-6233
800-800-1020

 

[davecook]

thanks for the phone number

 

[Osprey]

The best method to avoid the autopilot behavior described above is to manually steer the boat onto the displayed course before pressing the engage option.

 

[baz]

The best method to avoid the autopilot behavior described above is to manually steer the boat onto the displayed course before pressing the engage option.

This what I also do, but only after I had been following the course and had to deviate from it for some reason. If this isn't done the AP can make some severe and somewhat disturbing/stressful turning maneuvers to get back on course.

What I ended up doing in the above condition, especially if I'm 500 feet or more off course having previously disengaged the AP to make a deviation, I simply have the Garmin recalculate the 'safe course' and then use it to "Guide To" and engage the AP. This technique avoids having to get back to the original course which takes time and requires needed attention to the AP's control panel watching how far off course you are.

Of course, when fiddling with the AP like this it's essential you have your lookout person keeping an eye open for other boats etc.