Electronically Challenged - Old AP to New Chart Plotter

[cbouch]

I will start by stating that I am electronically challenged so please keep explanations simple if possible. I will also state up front that I searched this forum for answers to my question and they were so technical in nature I got totally lost. Perhaps that is the way it has to be and if so will have to hire someone anyway here is my question:

I have a autohelm st6000 and sea talk 1 installed on my boat. Currently this system interfaces to an old Garmin Chart plotter that I understand works OK providing waypoints and tracks to the autopilot. I want to install a radar package from Garmin that includes chart plotter 742xs which has nmea 0183 input and output ports. It is my understanding that the st6000 and seatalk1 also have nmea 0183 capability.....

Has anyone had any experience hooking the older auto helm package to a newer technology chart plotter. Thanks, Cliff

 

[tiltrider1]

Your current set up is using NMEA 0183. Find the two wires that go from your autohelm to your current Garmin. Identify which one is NMEA 0183 (+) and which one is (-). Make sure your new set up has a NMEA 0183 4800 baud output. Connect the two wires to it, (+) to (+) and (-) to (-).

 

[STB]

Your understanding is exactly correct. You've got two options.

The most direct is just to attach the 6000 to the new chart plotter via NMEA-0183. Just connect the wires output-to-input and call it a day.

If you have other NMEA-0183 devices, you might need to get a NMEA-0183 multiplexer. Basically, a little box that a bunch of NMEA-0183 devices plug into so the messages can go in a bunch of directions. Think of it a little like a star in the center of the wiring with some number of inputs and outputs (the more you pay, the more you get).

Another option is a little more convoluted. You could use a Raymarine Seatalk<->SeatalkNG converter to get the the SeaTalk-1 messages to Seatalk-NG. Seatalk-NG is basically a NMEA-2000 standard with different connectors. So, you could then use a converter cable to go from the Seatalk-NG converter to the Garmin's NMEA-2000 input. Key advantage of NMEA-2000 over NMEA-0183 include its much better ability to share the wire among multiple senders and receivers (no multiplexer) and a higher data rate.

I've never set up exactly this pairing of devices via a ST-1 <-> ST-NG bridge, so there is some risk that the conversion might mess things up, etc, so you'd need to test to know for sure. But, I doubt there would be problems.

Having said that, I, myself, ran into problems with conversion between my ST-NG autopilot and my NMEA-0183 plotter when I integrated my system and it took a ~$200 device to fix it for me. Basically, Raymarine uses some proprietary NMEA-2000 messages that aren't handled properly by converters that don't specifically address them.

Good luck!

 

[Ski in NC]

I messed with connecting my old Simrad AP 35 to a laptop running Coastal Explorer. NMEA 0183 vs 2000 type stuff. I finally got sick of messing with it and it sorta worked but then did weird things. Came dang close to throwing expensive bits out the window.

Now, years later I still run CE and the AP35. I just set a heading in Auto and tweak it as necessary to keep me on course. I've got to be at the helm anyway, so it gives me something to do.

 

[JDCAVE]

I messed with connecting my old Simrad AP 35 to a laptop running Coastal Explorer. NMEA 0183 vs 2000 type stuff. I finally got sick of messing with it and it sorta worked but then did weird things. Came dang close to throwing expensive bits out the window.

Now, years later I still run CE and the AP35. I just set a heading in Auto and tweak it as necessary to keep me on course. I've got to be at the helm anyway, so it gives me something to do.

That’s kinda what I do too.

 

[syjos]

I messed with connecting my old Simrad AP 35 to a laptop running Coastal Explorer. NMEA 0183 vs 2000 type stuff. I finally got sick of messing with it and it sorta worked but then did weird things. Came dang close to throwing expensive bits out the window.

Now, years later I still run CE and the AP35. I just set a heading in Auto and tweak it as necessary to keep me on course. I've got to be at the helm anyway, so it gives me something to do.

My Robertson AP 35 is interfaced to my laptop running Nobeltec using the Nobeltec serial cable and a serial to USB adapter. It works great on Nav, following my routes and making course changes, with permission.

 

[cbouch]

Thanks everyone I think I am now on my way..checked with Garmin today and the plotter has output at 4800 on 0183 mode so we should be good to go..

 

[Simi 60]

That’s kinda what I do too.

Me three.

Ours will run a course via plotter but it freaks me out the way it does a hard , instant turn when coming to a turning point whereas I like to do a more relaxed turn.

 

[Maerin]

Me three.

Ours will run a course via plotter but it freaks me out the way it does a hard , instant turn when coming to a turning point whereas I like to do a more relaxed turn.

Look into the chartplotter configuration. There are usually settings to configure how the chartplotter handles course changes. There are two typical methods, either entering a circle described around the center of the waypoint, or crossing a line perpendicular to the center of the waypoint. My experience is that perpendicular is not as smooth as the radius. There are also ways to fine-tune those course changes, the configuration of the radius distance can help smooth things out. IIRC, Simrad will make changes in course up to 30 deg with no supervision. Raymarine requires acknowledgement, as I believe does Garmin. There should also be response configurations in the AP that may help smooth out turns. You'll have to review the manual to get the details of how your particular gear can be configured & tweaked.

 

[Simi 60]

Look into the chartplotter configuration.

Thanks, I figured there would be a way of tweaking but reality is that I prefer to stay in control as usually, at turning points, there is something to hit.

Happy enough for the AP to hold a straight line or "goto" a point.
I find that impressive enough.

 

[RT Firefly]

Greetings,
Me four. Our AP (Wood Freeman) don't talk to nobody BUT it holds a steady course in almost any sea conditions we've experienced.

 

[koliver]

My Raymarine AP will follow the course from my GPS, if I let it. In following a course, it will wander to the extent of the allowable cross track error, then alter course by 20°, without warning. Then when the X-track error has been corrected, it will turn back 20° in the other direction.
I like to be in better control than that, so I don't use the "track" function except in very open waters, to avoid surprise meetings with other boats.

 

[tiltrider1]

If you hit the “reset track error” button right after the acknowledgement button you will get a smooth course change.

 

[Playin Hooky]

I've tried to get my older Comnav 1001 to work with Time Zero Nobeltec. The 2 talk to each other but I get strange course variations. I called both tech support lines and got 2 contradicting stories. Has anyone had success getting this combination to work?

 

[STB]

Playin Hooky,

Can you describe the "course variations" in more detail?

One common source of problems on unit from that era involve the "sense" of the XTE (cross-track error). The standard uses the terms "left" and "right" and defines them in terms of which way the vessel should steer. Many manufacturers define it (incorrectly) as the direction of the error, e.g. to the left or right of where the vessel should be. If the devices are not in parity w.r.t. this definition, the AP will start out turning to the correct course, and then misinterpret the direction of the error and steer further and further the wrong way, turning more and more off course. If the AP is reset, it will turn to course -- and then start steering away all over again.

This is easy to fix as that AP unit can be set to a "reverse" course response. (Or, can be set to a "normal" response if it is currently set to "reverse"). This is set by pressing buttons on the main control head (not the remote).

Another common source of error is having multiple navigation GPS sources providing slightly conflicting data. This normally manifests itself by things working normally for a while, but getting a bunch of conflicting course corrections and swinging XTEs (if you can monitor those) as the waypoint starts getting close. The way to fix this is to ensure the control head is only getting data from one NMEA source. Some can pick -- but I don't think most from that era have that ability.

I hope this helps. With a better understanding of what is going wrong I might be able to help more.

 

[Playin Hooky]

Playin Hooky,

Can you describe the "course variations" in more detail?

One common source of problems on unit from that era involve the "sense" of the XTE (cross-track error). The standard uses the terms "left" and "right" and defines them in terms of which way the vessel should steer. Many manufacturers define it (incorrectly) as the direction of the error, e.g. to the left or right of where the vessel should be. If the devices are not in parity w.r.t. this definition, the AP will start out turning to the correct course, and then misinterpret the direction of the error and steer further and further the wrong way, turning more and more off course. If the AP is reset, it will turn to course -- and then start steering away all over again.

This is easy to fix as that AP unit can be set to a "reverse" course response. (Or, can be set to a "normal" response if it is currently set to "reverse"). This is set by pressing buttons on the main control head (not the remote).

Another common source of error is having multiple navigation GPS sources providing slightly conflicting data. This normally manifests itself by things working normally for a while, but getting a bunch of conflicting course corrections and swinging XTEs (if you can monitor those) as the waypoint starts getting close. The way to fix this is to ensure the control head is only getting data from one NMEA source. Some can pick -- but I don't think most from that era have that ability.

I hope this helps. With a better understanding of what is going wrong I might be able to help more.

It tracks fine for a minute or 2 and then starts veering off course with no correction Sounds like the course response may be out of whack. I’ll have to dig into the comnav literature a little more to see if I can find out how to reverse or reset.

It only has 1 GPS source. The more I talked with tech, the more frustrated I got with trying to adjust settings on 2 separate pieces of equipment to no avail.

 

[STB]

Playin Hooky,

Okay. That really sounds like the cross-track error thing. Really common.

I found the manual on the Web. See page 26 for the adjustment procedure. It is fast and simple, but a little counter-intuitive, I think.
-- http://www.comnavmarine.com/manuals/1001_Installation_Operation_Manual.pdf

Cheers!
-Greg

 

[STB]

Playin Hooky,

Also, I'm jealous of your boat. I used to have on of those. I like my current Europa-style Hardin a lot. But, my 1977 42' Californian LRC was my first boat and I restored it from a 10-year slip queen live aboard. I loved the relatively large cockpit, 360 degree sunlight in the salon, huge staterooms, dual heads, and nice sized flybridge. I haven't hard the Hardin out in really, really rough seas, but that California sure could take a beating better than its crew. Fond memories!

 

[Playin Hooky]

Greg
Thanks so much for your help. I’m going to attempt the process again with a clear head and the new info.

I bought the boat April 2017. It was in rough shape and not updated but it had fresh Perkins re-power. I like the layout and visibility. We’ve had a great time with her so far.

Thanks again,
Scott

 

[STB]

Scott,

I just PMed you with a link to some documentation I collected on mine in case it is ever of any help to you.

-Greg

 

[Playin Hooky]

I’ll check it out. Thank you!

 

[Aquabelle]

It tracks fine for a minute or 2 and then starts veering off course with no correction Sounds like the course response may be out of whack. I’ll have to dig into the comnav literature a little more to see if I can find out how to reverse or reset.

It only has 1 GPS source. The more I talked with tech, the more frustrated I got with trying to adjust settings on 2 separate pieces of equipment to no avail.

Playn....you need a Heading sensor for correct autopilot operation, not just a gps source. Do you have a Heading sensor of some type connected ?

 

[STB]

On that unit, the compass should plug into a compass portbon the back of the head unit. I'm assuming it is there or the Autopilot should error out rather than get off course. Assumptions, of course, can be bad!

 

[sunchaser]

Me five

When operating in Nav mode in tight waters with logs, rocks, kelp floating, commercial traffic and whales - too many dangers become the proverbial accident waiting to happen. Our vessel has two independent plotting units with selectabilty to either a Maretron or Furuno heading sensor. Both options work as intended in the Nav mode, steering willingly to the almost certain collision or grounding points.

So a sharp eye (my wife's) is needed, in the Auto or Manual mode, in those certain collision or grounding situations. BTW, boating mags and insurance reminders keep popping up alerting us as to inherent hazards of blissfully operating in the Nav mode. A perfectly operating AP in the Nav mode may not always be our friend.

 

[Playin Hooky]

Playn....you need a Heading sensor for correct autopilot operation, not just a gps source. Do you have a Heading sensor of some type connected ?

It has an operating compass/heading sensor. The AP works great on its own.

 

[syjos]

Me five

When operating in Nav mode in tight waters with logs, rocks, kelp floating, commercial traffic and whales - too many dangers become the proverbial accident waiting to happen. Our vessel has two independent plotting units with selectabilty to either a Maretron or Furuno heading sensor. Both options work as intended in the Nav mode, steering willingly to the almost certain collision or grounding points.

So a sharp eye (my wife's) is needed, in the Auto or Manual mode, in those certain collision or grounding situations. BTW, boating mags and insurance reminders keep popping up alerting us as to inherent hazards of blissfully operating in the Nav mode. A perfectly operating AP in the Nav mode may not always be our friend.

We use Nav 90% of the time. There is a Dodge button to dodge logs, other boats etc.

In areas with strong current, Nav is the mode to be in. It will compensate for drift better than any human. And when steering a route between closely spaced underwater rocks, with many sharp turns, the autopilot on Nav can turn faster and more precisely through the tricky passage. Beware Passage in the Broughtons BC comes to mind.

 

[Playin Hooky]

Playin Hooky,

Okay. That really sounds like the cross-track error thing. Really common.

I found the manual on the Web. See page 26 for the adjustment procedure. It is fast and simple, but a little counter-intuitive, I think.
-- Home | ComNav - Ingenuity in Motion

Cheers!
-Greg

Hi Greg,

Good news! I got the Time Zero and the Comnav working together. I recalibrated the fluxgate compass offset in the auto pilot to match the GPS COG heading on the computer. Nobeltec recommended APB, RMC, XTE outputs to the autopilot. Bingo. The cross track is still a little more liberal than I like, but I can work on that. Thanks for your help.

Scott

 

[STB]

Hey Scott,

Good work! Congratulations!

-Greg