Now you know why I asked such basic questions that some of you thought heavy on Curtis.
_____ From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Rich Knowles Sent: January 13, 2014 5:27 PM To: cnc-list Cnc-List Subject: Re: Stus-List Autohelm St4000 how it should work with the GPS Curtis: The fluxgate compass is the primary source of heading information for the autopilot head and should not be disconnected. When you push the "AUTO" button, the course computer locks on to the compass heading the boat is on and develops internal correcting signals as the boat yaws to either side of the original heading and uses those cross-track error signals to drive the wheel and hold the course steady. Once properly set up, the course holding abilities of the ST4000 are quite good and you should be on a constant course in the direction originally set. This way of using the ST4000 is the standard way of operating. It's just fine for relatively short legs but, as it only uses the boat's heading as a reference, it cannot compensate for current or leeway of the boat. In other words, you could be doing 220 deg for several hours and be miles of your intended destination if a cross current caused by tide has pushed you away from the rhumb line. To avoid getting pushed off course by factors that the fluxgate compass cannot measure or compensate for, an external source of cross-track error signals is needed that uses the final destination point as the reference from which to calculate whether course correction is needed. When you have a "GO TO" destination set up and activated on the GPS unit, the GPS will develop off course signals that can be used by the auto helm computer to steer the boat to the destination. That information is delivered to the ST4000 via the NMEA signals. Pardon me if you are aware of this already. I strongly recommend reading the manuals and, if there are terms that are unclear, Google them up. Hook that compass up and RTFM! Rich Knowles INDIGO LF38 Halifax, NS. On Jan 13, 2014, at 4:26 PM, Curtis <cpt.b...@gmail.com> wrote: I have a flux gate compass I disconnected it from the head because I thought the auto-pilot head would now get its heading from the GPS unit? So I will take some photos and show you what I have. How will I ever nap a nap in??? On Mon, Jan 13, 2014 at 2:19 PM, Michael Brown <m...@tkg.ca> wrote: >Though something to consider is that the 0183 standard is for a total of 4 >wires to send and recieve. RX+GND and TX+GND. I didn't see where you >mentioned all those wires...sounded like too few. The ST4000 control head is NMEA IN only, two wires marks - +. > > So now, If I understand you correctly. I first have to create a route then to > start navigating a course or to a way-point. That should start > broadcasting a course to steer signal. then I in-gauge the st4000 by > pressing the +10 and -10 at the same time and it should start taking > direction from the Garmin? > does this sound correct? > With NEMA to the ST4000 it depends on what is being sent. Autohelm describes two scenarios, automatic acquisition and manual acquisition. Automatic - both cross track error and bearing to waypoint are sent Manual - only cross track error is sent With automatic get everything engaged and press +10 and -10 together. The manual requires that you get on course withing 5 degrees of the bearing to the waypoint and cross track less than 0.1 nm, then press +10 and -10 together. My guess is, and strictly a guess, is that the ST4000 uses its own fluxgate compass for navigation and takes some error correction from NEMA for cross track. >I know it has probably been done by others but I am not sure that I would >ever let my ST 4000 plus steer a course unattended based on transfer data >from my chart plotter. I wonder if that was what Autohelm was thinking, they seem to use the fluxgate compass. > Curt ? it?s been my experience that pretty much NO equipment uses the same color wire for the same thing, even among equipment from the same manufacturer. >You need to connect the NMEA0183 output wires from the GPS to the NMEA0183 input wires on the > autopilot; TX+ and TX- on the Garmin to RX+ and RX- on the Raymarine. >I can guarantee that the chances of any two of these wires having common colors is about zero. Supposedly the + is Red and - is Blue, however Autohelm agrees with you. They are marked + and - only. Michael Brown Windburn C&C 30-1 _______________________________________________ This List is provided by the C&C Photo Album http://www.cncphotoalbum.com <http://www.cncphotoalbum.com/> CnC-List@cnc-list.com -- At sea, I learned how little a person needs, not how much. - Robin Lee Graham _______________________________________________ This List is provided by the C&C Photo Album http://www.cncphotoalbum.com CnC-List@cnc-list.com _____ No virus found in this message. Checked by AVG - www.avg.com Version: 2012.0.2247 / Virus Database: 3658/6498 - Release Date: 01/13/14
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