[CA] [CA11] How Much "Wandering" is Acceptable on EV150

[GoodChance]

I'm having an ongoing "issue" with a newly installed EV150 (installed June 2018). It seems that I'm getting an awful lot of "wandering" in calm seas and river operation. I'll set the course to a known waypoint and the boat will wander by 5 to 6 degrees to port and then starboard (so a total of a 10-12 degree arc). Is this much wandering in flat seas acceptable? I should point out that the boat rarely deviates from a straight-line course by more than 50-75ft from point-to-point even when this course is 25-50 miles. So I'm pretty happy with this aspect but I wonder why the autopilot forces the boat to wander by 10 degrees.

All of the operating software on the AP is the most recent version (ACU is v2.23; Control head is v3.07). The calibrated max deviation on AP is 4.3 degrees. The compass is located in the console and not within 5ft of any ferrous materials.

I have lowered the "hard-over" time from a default of 10 seconds to 5 seconds. And I have played with the "dampening" features. The compass calibration was left "open" as opposed to "locked or closed".

The EV150 is networked to an a128. And if it means anything to you, there is also an a78 working as a slave to the a128. There is also a RD424 Digital radome connected to the a128.

The wandering used to be MUCH worse and was 20-30 degrees at one time. A Raymarine field technician visited the boat and we went for a short ride. He immediately saw the problem although he couldn't figure out what was the cause so we replaced the ACU, the pump and the compass. The wandering improved but I question whether the AP could be more efficient.

The boat is a 23ft Parker center console with a single Yamaha F250.

Your thoughts?