Late season GHC 10 question

[rpmerrill]

I know it is late in the season, but I noticed something happening with my GHC operation early in the season. I never got a chance to really mess with the problem because the First Mate would always say, "Stop screwing around and drive the boat!"
I did get a glassy water day, yesterday, and went out (alone) to experiment.

What I've noticed is that the boat would typically overcontrol when making turns. When I have a turn on a route or if I simply designate a "go to" point on the chart and say "go" the boat will oversteer about 30 degrees and then have to correct back to the intended route of course. It makes it appear as if the Captain is drunk. I think it happens at higher and lower speeds but it's hard to recall exactly. I should have run that test a little more specifically.

Anyone have any ideas? Are there response coefficients built in somewhere in a deep multistep settings menu?

 

[Cutwater28GG]

I have the same thing!

my assumption is either

1. the direction sensor isnt sampling the data often enough or accurate enough.
2. its by design
3. my heading calibration is out by enough of an error which is effecting the efficiency of this feature. ( I notice my heading calibration is out when either the boat is trim tabbed to level with an even load causing the boat to crab or there is a strong current in effect)

its a little disconcerting when in close quarters with other boats to have the boat spear off dramatically!

 

[Wee Venture]

When you first turn the autopilot on, the boat will often veer off course substantially before finding its bearings. This is annoying and potentially dangerous but I have learned to anticipate it. If it continues to oversteer, however, it might help to check the setup settings on your autopilot - namely, that it has been set correctly for planing or displacement hull, the maximum rpm has been entered correctly and that the “speed source” has been set for engine rpm rather than gps. You might also need to do the sea trial portion of the setup again. You could try just doing the “zig zag” portion. I believe that is where the autopilot learns how far to turn the rudder to make a given change in direction of travel. I have been told that should be done at a moderate cruising speed. If it is done too slowly, as I understand it, the autopilot will have to turn the rudder farther to change course. That might not be the problem but is something to check.

 

[Brian B]

If the CCU has become loose you will get symptoms as described.
See this previous post viewtopic.php?f=2&t=13695
If you have to replace the bracket the A/P has to be recalculated.

 

[GZigmont]

Just traded my MH40 sailboat with Raymarine Autopilot on a new R29CB. The Raymarine autopilot had the same characteristic, but it was normal and part of the program. The oversteering and correction were even spelled out in the instruction manual. I would expect Garmin to be the same. Hope this helps.