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+--- Thread: [TG] [TG11] Linear Drive "Fluttering" when turning to Port (/showthread.php?tid=8089)
[TG11] Linear Drive "Fluttering" when turning to Port - bmackie - 04-30-19 03:44 PM
Hello:
We have a mono hull sailboat. I recently replaced my Type 2 Linear Drive after noticing "play" in the linkage and Drive Hinge. (The tiller pin broke at sea, probably caused by the play. About 27,000 miles on the drive at the time.) All rod ends were subsequently changed at the same time as the Drive Unit.
That was about 1000 miles ago. Recently we noticed that when the Autopilot is turning the vessel to Port, we are getting a clunking sound in the linkage. Visual inspection confirmed that it appears the Drive is "fluttering" when turning to port. We confirmed that this is ONLY when the Autopilot is engaged and not when hand steering. Continuing to trouble shoot today I decided to do a Dockside Calibration and found that during the Calibration and the Drive was turning to Port, the unit worked flawlessly. After the calibration, we engaged the autopilot and again, the clunking issue was still present. To be sure, I did another Dockside Calibration and again, it worked fine when the drive was turning to port but not after the calibration.
So, is this possibly a ACU 400 issue or a drive issue?
My system is partially as follows:
ACU 400 Actuator Unit s/n 0930029 2.23 (RSCP V1 L4)
EV-1 s/n 0631542 2.18 (RSCP V1 L4)
p70 Autopilot Controller s/n 1130032 3.07
e125 s/n E70023 0730345 V19.03-00036
I do have a Spare ACU 400, EV-1 and p70 on board.
On a similar note; I am currently in French Polynesia. Where should I send my Linear Drive that I removed for service?
RE: [TG11] Linear Drive "Fluttering" when turning to Port - Tom - Raymarine - Moderator - 05-01-19 10:05 PM
Hello bmackie,
If the drive consistently works as expected when you're doing the dockside calibration, then to me that doesn't sound like a fault with either the linear drive or pilot electronics: I think that if they were faulty you'd see the same thing in dockside calibration as in normal use. If you're having problems only on normal use then I would say that's more likely to be down to something like incorrect/misleading sensor data.
Have you got the rudder position sensor (supplied with the EV400 pilot system but not always installed) fitted? If so, I think it would be good to have a very careful look at the displayed rudder position when the pilot's in Standby. If you very slowly wind the wheel from lock-to-lock several times, do you ever see any flickering/jumping of the rudder bar, does it ever indicate an incorrect value? The rudder position sensor is a potentiometer and as an electromechanical device with a moving part they can occasionally develop 'dead' spots where they read incorrect values. This would cause this sort of problem. If in doubt, it would be good to test with the rudder-reference unplugged from the ACU's connector panel.
If this doesn't solve the problem, please could you do two further things in order for us to have more detail about the problem?
1. Video what the linear drive is doing so that we are both clear about what the fluttering behaviour looks like.
2. Record some NMEA2000 data whilst the pilot is in use and the problem is apparent. Please go into the pilot Menu > Setup > Autopilot Calibration > Commissioning and set Debug to 7 and ACU Debug to 31 (make sure you set these back to 0 after you're done.) You'd need to record somewhere between 1 and 10 minutes of data, but this needs to be when the pilot is in use when under way, not dockside, so we see real-world data.
Please post the video and log-file back here so that I can have a look.
Thanks,
Tom
RE: [TG11] Linear Drive "Fluttering" when turning to Port - bmackie - 05-02-19 05:11 PM
Hello Tom:
We did have the rudder sensor installed. I disconnected it as you suggested and the problem appeared to go away.
I installed a "new" Rudder Sensor that I had as a spare and the problem now seems to rectified. I should note; prior to disconnecting the old unit today I also noticed that the rudder angles display seemed off. When the display had indicated full travel, in fact, the wheel continued to turn a significant amount - about 2 spokes (on our wheel) worth to Starboard and 1 spoke worth to Port.
I never did witness the "flickering or jumping" of the display rudder bar though.
With the new sensor the wheel stops almost immediately when the display bar reads full travel and is now traveling smoothly.
Thanks!
Bob Mackie
sv Hedonism
Outbound 46
RE: [TG11] Linear Drive "Fluttering" when turning to Port - Tom - Raymarine - Moderator - 05-12-19 06:45 PM
Hello Bob,
The rudder bar on the display is designed to show a specific (numerical) rudder angle, e.g. 25 degrees port, rather than scaling to your boat's range. The software of the display sets the upper limit for displayed rudder angle in the bar at 30 degrees either side, which covers the majority of boats. If your boat has more than 30 degrees of movement either side then that simply can't be displayed by the pilot controller.
The pilot has a software setting, Rudder Limits, which controls the maximum range of motion that it will try to drive to when Auto/Track/Vane/Power-Steer modes. This defaults to 30 degrees but should be calibrated at installation to match your boat, and should be set - as it sounds like yours is - to a few degrees narrower/before the physical end-stops. This is to prevent the pilot driving up against the physical end-stops and stalling and perhaps damaging stuff. I mention this just for completeness.
I'm glad to hear the new rudder reference has solved the problem.
Regards,
Tom
RE: [TG11] Linear Drive "Fluttering" when turning to Port - bmackie - 05-13-19 06:49 AM
Tom;
Thank you. I have since left the boat for 4 months (first time off in 2 years) so I have yet do a check underway.
I am pretty sure it is resolved though.
Thank again.
Bob