ST4000 / NMEA 0183

[Craig Illman]

Anyone have their ancient ST4000 connected to a NMEA 0183 device? Would I see any advantage feeding it GPS sentences for heading information in addition to it's fluxgate compass?  I still seem to need to tune it a bit, it wanders quite a bit compared to my Simrad wheelpilot I used to have on my C34. There's not really any room on my C30 to install a rudder position sensor.

Craig

[Stu Jackson]

Anyone have their ancient ST4000 connected to a NMEA 0183 device? Would I see any advantage feeding it GPS sentences for heading information in addition to it's fluxgate compass? 

Craig,

Disclaimer:  I don't have an ST4000    But the issue you raise is one of interfacing devices or not.  I used to disagree with interfacing an AP with a GPS, until someone noted very clearly to me that the AP would not blindly follow a course, you HAD TO acknowledge the new heading before the AP would make a turn.  So, first, I felt that made sense, for safety purposes.  And, second, I then realized that if you had to go to the AP to acknowledge the turn, why did you bother to interface the stuff to begin with?     Why not just take the same effort to go to the AP and push the course change?     What's this big thing about interfacing?  I still don't get.  But that's just me with my ST3000 and a handheld Garmin GPSMap76Cx.  Old school, still with paper charts and dividers, too. 

I still seem to need to tune it a bit, it wanders quite a bit compared to my Simrad wheelpilot I used to have on my C34. There's not really any room on my C30 to install a rudder position sensor.

I had the same thing with mine, but, of course, my neanderthal ST3000 doesn't need a rudder sensor.  Imagine that!  Everything is in the one little control head box!!!  How'd they do that and then in later models make basic stuff so hard?  In coming down the coast of Northern California from San Francisco to Half Moon Bay (about 20+ miles from the Golden Gate Bridge), we had quartering swells with NO wind, which made for a noisy ride with the AP whining and bitchin' more than a real crew member would!  So, I pulled out the handy manual and found that if I recalibrated the GAIN, the AP didn't chug around so much.  It also, of course, made it slower to react.  So, when we got back into the busier Bay a few days later, I just had to reset the gain again.  You may want to check the AP manual for your ST4000 under Calibration and see if you can set the gain to a lower (at least on my unit) value.  It's very easy to do from the keypad.  Oh, it was a verrry quiet trip back up the coast, again, no wind, but a very quiet AP! 

Good luck.

[Craig Illman]

Stu - Thanks. The goal is to give it more stable heading information than it might be getting from the fluxgate that's mounted on the aft wall of the quarterberth. I'm not giving it a course, although a Bearing to Waypoint from the chartplotter would be handy. Yes, I need to fiddle more with the Gain and other settings. I did the "Catalina cocktail" but it still needs a little fiddling. I'm 75% done with a NMEA 2000 network. I'm getting an AIS-B transponder that has a couple NMEA 0183 outputs, besides the NMEA2000 connection. It won't be a difficult wire run to the AP to feed it the GPS info. I was just curious if would be worth the trouble. (What else am I going to do over the winter anyway?)

Craig

[Roc]

Craig,
I see what you're talking about...  Yes, you would want your GPS to tie into the autopilot.  The AP will set a course heading either by compass, or wind. With the GPS input, you can also track to a waypoint.  Mine was connected like that when the dealer set up my electronics when I bought the boat.