Evolution ACU-200 Excessive Response and Inability to Maintain Course

[chartertom]

I am looking for suggestions on how to resolve two issues with an Evolution ACU-200 autopilot.

First some background, this unit installed on a 23-foot fiberglass center console boat with a 24-degree deadrise hull with automatically controlled trim tabs, is fitted with a rudder reference transducer, is fitted with a type 1 hydraulic pump, is connected to a pair of Raymarine e125 MFD’s, includes a P70Rs (E22167), had software updates, was successfully commissioned using the Dockside Wizard with original vessel hull type set to “Power”, and compass linearization was successfully completed.

The first issue is when operating in “Power Steer” mode, the autopilot continuously oscillates the motor a few degrees from port to starboard to the extent of noticeable zig-zagging and boat continuously tilting from port to starboard due to 24-degree deadrise. The first attempt to resolve this issue was to change vessel hull type set to “Power (slow turn)” and confirming response level saved to “Leisure” and repeating the dockside setup wizard. This resulted in a negligible improvement. This autopilot was not tested in “Track Mode.” Will changing the hull type to “Sail” or “Sail (Slow turn)” and keeping response level to “Leisure” reduce the autopilot’s response / oscillating?

The second issue when operating in “Power Steer” mode, in addition to the first issue described above, the autopilot will steadily and consistently veer off course to starboard. The severity of this issue results in an off course alarm sounding in approximately 0.33 Nm travel. This autopilot was not tested in “Track Mode.” The first question is does the autopilot automatically correct course over ground to compensate for wind and current while in “Power Steer” mode? If the does not correct for wind and current, what can be done to correct this issue?

[Chuck - Raymarine - Moderator]

Welcome to the Raymarine Forum Tom,

What was the maximum value of deviation detected by the autopilot? Is the system interfaced to a speed through water sensor (i.e. when the MFD is configured to display the Speed data item within a databox, if the reported value dashes, then no speed through water source has been interfaced to the system). If so, when both the Speed and SOG data items are displayed, and the autopilot is exhibiting the symptoms reported, how close are Speed and SOG in value?

[chartertom]

There is a maximum deviation value of 6-degrees.

Speed through water sensor was thought to be a Temp-Speed ST69 transducer through a CP570 Sonar Module displaying 0.0 (no dashes).

Speed showed 0.7 knts when SOG showed24 knts.

It was found the autopilot data source lists a Suzuki engine, but not ST69. The Suzuki had its pitot tube clogged. It was cleaned and showed reasonable speed when hose tested. Autopilot will be tested on water during the next trip.

Any guess why the ST69 is listed a possible data source for MFD, but not the autopilot?

[Chuck - Raymarine - Moderator]

Tom,

Should the ST69 have been mated a compatible 50/200kHz transducer which in turn had been interfaced to the CP570 and should the Transducer Settings within the Fishfiinder application have been configured to identify that a ST69 Speed Transducer has been interfaced the CP570, then the CP570, not the ST69, should be listed as a Speed source within the Data Sources feature. Note that the default setting for Speed Transducer within the Fishfinder application's Transducer Settings is None. Similarly, should the ST69 have been interface to an iTC-5 or i50 Tridata, then the iTC-5 or i50 Tridata respectively should be listed as a Speed source within the Data Sources feature.

[chartertom]

Chuck:
You are the greatest. Looked at fishfinder setup menu for CP570 and selected speed transducer ST69. Did same for DSM 300. Found both CP570 and DSM 300 listed as possible speed data input, as well as Suzuki motor. Selected automatic option. Will test on water when possible.

[chartertom]

In follow-up to my 25-08-2017, 02:32 PM post, the vessel was tested in "Auto" mode and performed perfectly. This issue is resolved. It was concluded that excessive steering response while at planning speed was the result of having an inaccurate speed input. Thanks much for the support.

[Chuck - Raymarine - Moderator]

You're welcome.