Auto pilot - opposite directions

[Rich18836]

We have a 1991 Hunter 30T with an Autohelm (Raymarine) ST4000 autopilot. It was installed in 1993 and we bought the boat about 8 months ago. The boat was in excellent condition and well maintained and even has all of the original manuals and the ones for each item added since original purchase through 2003). As an autopilot, it does its basic job of keeping the boat on the pedestal compass setting. The problem is that the ST4000 display head reading is not synchronized with the pedestal compass. We have tried most everything to solve this. We have followed the manual (several times) as how to compensate for the deviation. This includes setting it to the calibration mode and turning 360 degrees (under 2 knts) 2 to 3 times or until it beeps. We then set the pedestal compass on a known bearing and +- adjust the autopilot to coincide and lock the setting in, just as the manual says. THE PROBLEM is after we lock the settings in, the strangest thing happens. Say we synchronized at 60 degrees, as soon as we steer to increase to, say 75 (+ 15 degrees) the autopilot will go to 45 (- 15 degrees). If we continue to 80 it goes down to 40. It goes in the exact opposite direction the same amount of degrees no matter what or how many times we try to recalibrate it.The fluxgate compass is mounted amidship in the galley (as it has been since 1993). The previous owner was an accomplished sailor so I cannot imagine that he would have lived with this, unfortunately he is not available to get his advice on this. I suspect it is a new problem even though we have not added any new mechanical or electrical items that may adversely affect the autopilot.The good news is, as I said, the autopilot does the basic job of staying on the pedestal compass course setting; it’s just that the two readings don’t match. I can live with this temporarily but need to solve the problem when I hook up my GPS (with waypoints) to drive the autopilot, to drive the rudder, etc.I don’t think it is a deviation problem, I suspect it is either a fluxgate problem or an electrical problem. My suspicion is electrical or magnetic because of the reverse polarity (degree-wise). Additional information is when we first bought the boat and turned on the autopilot it sometimes would not come on, but if we jiggled the cable to the battery around the fuse connection, it would come on. But, we have not had that problem for 3-4 months; it turns on every time now.Sooooooo, I would like some advice from those that may have had the same experience or have a much more in depth knowledge of the workings of the autopilot ST4000. I have read just about everything in the archives and tried those that I thought applied, but to no avail.I realize it is a lot to dump on you guys/gals and I know it is difficult to do remote diagnosis, but since I have been on this web site I have been extremely impressed with the vast and varied experience that exists and the willingness to help.Thanks, Rich

 

[Allen]

Easy Fix, I think...

Rich,If you have a rudder reference transducer, this is an easy fix. Just switch the red & green wires on the back of the autopilot control head, as described on page 90, section 6.2, instruction #1. In other words, connect the red where the green one was, & vice versa.This will fix your problem.If you don't have a rudder reference transducer, I'm not sure how to fix your problem.Good luck,Allen Schweitzers/v FalsaffC-30 Hull# 632

 

[Paul (Affinity C320)]

Call Raymarine

I have a problem that sounds close but no time to work on it yet. The fluxgate is not in sync with with my pedestal compass. I did notice one thing -- my fluxgate is set on true and when I installed the GPS, I used magnetic which put it in sync with the pedestal but not the fluxgate. So I put the GPS on true and seemed to help but its still out. Before I call Raymarine, I need to do the set up routine on the ST4000. Check to see that all are set to true -- or magnetic. Good luck.

 

[Don12364]

Beware

I am not sure that Allen's advice is correct. The rudder reference unit serves to tell the pilot where the rudder is rather than anything to do with the boat's magnetic heading. If you reverse its sense the boat should go into an unconstrained course oscillation of ever increasing amplitude. This happened to me when first time connecting another make of autopilot. If anything the wires to the display could be crossed or one open may be circuit.

 

[Stu Jackson]

Deviation(?)

If it works backwards, something is reversed, either a wire or th calibration. There is material in the manual about that, but probably not about the good idea about the wires.Using true and magnetic is sure a confusing issue to deal with, why bother, just use magnetic all the time, that's what compass roses are for, unless you're going offshore on 1:1,000,000 charts. 20 miles a day doesn't need that complication.And never try to make them match perfectly, they won't and won't need to do so. 5 degrees or so difference is quite fine unless you never have a lookout.Good on you for checking the archives. I've never heard one like this before, but the solution is probably easier than you'd ever imagine.Good luck,Stu

 

[Lee Pryor]

Switching wires was my solution

I just installed a Raymarine autopilot on my J 109. The installation manual describes exactly your situation and says that the solution is to reverse the wires from the rudder reference device that go to the autopilot contoller box (computer). My below-deck installation required a tiller arm. There are several ways to install a reference depending on the boat's design in the rudder post area. It is a 50-50 propositon how to install the reference unit so Raymarine can't predict this. Sure enough, my installation turned out to be opposite the default but no biggie.How the previous owner could use the autopilot if the wires are reveresed is confusing since thhe amplitude of error would seem to constantly increase making the epilot useless.hope this helps

 

[Rich18836]

Autopilot - reversed has been reversed

Well, you guys came through with good advice, as always. Most of your suggestions were based on the reversed wires on the rudder reference transducer, but I don’t have one because mine is mechanical steering as opposed to hydraulic. However, this was a significant clue to the fact that a reversed wire within the autopilot path (even though it was on a feature I didn’t have, the rudder reference transducer) could result in the same symptoms as I had.So I started to trace the wiring path from inside the pedestal to the autopilot head and back through the fluxgate. Low and behold I found the reverse wire from the fluxgate to the autopilot head (see photo).It is interesting that if it were not for the clearly marked color-coding labeling on the backside of the autopilot head and matching color-coded wires I would not have a clue as to which wires could be suspect. There are 5 wires coming from the fluxgate and connecting to the back of the autopilot head and arbitrarily switching two (the resulting combination of possibilities is quite high) and subsequently testing each, would have been a big effort. Of course the same clearly marked color-coding label and color-coded wire apparently was not a failsafe for the original installer.I am assuming that this must have been like this since it’s installation in 1993 and the previous owner didn’t know how to fix it or decided to live with it because the autopilot worked fine for its basic intended purpose of staying on the pedestal compass heading (they didn’t have any GPS connected).Again, thanks for all of your help and advice that got me going down the right trouble-shooting path.Rich

 

[Roy Mosteller]

Would Like To Talk To You

Rich -I am also the owner of a Hunter 30T in San Diego and would like to talk with you as I might have some information on this model that may be helpful to you. Please contact me through the Owner Directory.Roy MostellerSEA JOY (1991, 30T)