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If you really wanted to simplify that and get rid of the OCPN/Ubuntu/Pi/router, then buy a Raymarine Seatalk to N2K converter and STNG-N2K cable for $100 and connect the AP to the N2K network ( https://www.amazon.com/Raymarine-Seatalk1-Sea-Talk-Ng-Converter/dp/B003E1WVRW ), connect the radio output to the NK-80, connect the radar ethernet to the back of the Zeus, use the Zeus's internal GPS, and toss the rest.

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If you really wanted to simplify that and get rid of the OCPN/Ubuntu/Pi/router, then buy a Raymarine Seatalk to N2K converter and STNG-N2K cable for $100 and connect the AP to the N2K network ( https://www.amazon.com/Raymarine-Seatalk1-Sea-Talk-Ng-Converter/dp/B003E1WVRW ), connect the radio output to the NK-80, connect the radar ethernet to the back of the Zeus, use the Zeus's internal GPS, and toss the rest.

Mark

It just occurred to me that you could connect the VHF/AIS directly to the NMEA0183 input of the Zeus and do away with the NK-80.

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The autopilot does not need wind unless you usually pilot to wind... in this case the autopilot directly connects its fluxgate..

I am not a fan of connecting single sided CAN to differential can, so i would be careful about connecting these three different 2k manufacturers together.. this would mean the 2k connects only to the Zeus. And Raymarine connects directly to its fluxgate.

This is probably the simplest solution that gets rid of ethernet, ubuntu, PI and all converters, without buying anything.
Not sure I understand your point about single sided CAN to differential CAN. I'm not even sure that is even valid electrically, since every single component listed is differential - even the converters. There isn't any such thing as "different N2K manufacturers" because N2K is just a standard that all manufacturers have to meet. There aren't different "flavors" of N2K, and even Raymarine's perversion of it is simply in the physical connectors only. Even the Seatalk converter to N2K meets the standard and works fine.

So put everything on the N2K bus and all will happily share data and work together.

Not having wind or navigation data available to the autopilot is severely limiting its functionality and usefulness. It can easily achieve all of its potential by connecting it to the main N2K network via the ST-N2K converter. Of course, the compass, rudder reference, and control head will all be directly connected to the AP computer, but the AP computer will be bridged to the N2K, so all wind, GPS and navigational data will be available to it, and its compass and rudder data will be available to the other components.

The above is from direct experience. We have a ST6001 AP system connected to a N2K bus that also has a dog's breakfast of different manufacturer equipment, including two 0183-2000 converters, and a Standard Horizon VHF/AIS. No problems at all with this.

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Concerning autopilots.

I believe most newer autopilots will interface with a GPS plotter and steer to a waypoint. But can those APs simply be set to steer a magnetic course?
Yes, that is the most basic level functionality that all of them share. All autopilots are standalone, and interfacing them just provides extra functionality.

Are sailors using AP these days mostly sailing to a fixed GPS determined location? Or are they sailing a magnetic course? Or are they sailing to a set wind angle?
.....
Are you using your AP to steer to a fixed coordinate (waypoint) or to a magnetic course (to a waypoint or mark/feature of the land etc.? Do you rely on tell tales, a windex or wind data on instruments when sailing with the AP?
All of the above.

AP to compass: used mostly when we just want to push a button to keep a straight course while we fiddle with something. Often used while entering/leaving an anchorage and getting things out/away before setting on a determined course.

AP to waypoint or course (pretty much the same thing): used a lot while actually sailing. Like you mention, one needs to trim sails accordingly while in use.

AP to wind: mostly used when beating or running because sails don't need to be trimmed and it prevents unintentional jibing or going in irons on wind shifts. Also often used when raising sails to keep the boat headed into the wind in an anchorage where the wind is usually shifty.

We rely on telltales to help with sail trim. Have a windex and wind instrument that are used to make navigation decisions - our favorite instrument setup is to have one instrument displaying the traditional wind rose with AWD and TWD along with instantaneous wind speeds, and another displaying a timeplot histogram of TWD and TWS. The latter gives us a good feel for changing wind conditions and whether they are temporary or truly changing.

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the PO specifically did not connect these two networks together.. rather, he connected them together through the RP.. so no he did not connect the 6001 to 2k
He did this for two reasons that I can see. First, he wanted the radar and all the data on OCPN, which doesn't use N2K for communication - 0183 and TCP only. Second, the Seatalk on his AP is 0183, not N2K, so the Pi is being used as a 0183 multiplexer. The later version of SeatalkNG is N2K with a non-microC connector. The only reason for this is because SeatalkNG carries an extra wire that makes it compatible with the older Seatalk. Otherwise, it is standard N2K. I just made a SeatalkNG-MicroC cable by cutting one end, clipping off the extra wire, and adding a MicroC connector.

If the OP wanted the Pi and Ubuntu units removed, then my suggestion above will work with no issues. There is no problem putting Seatalk onto a N2K network. They aren't two different versions of CAN - the Seatalk 0183 will be converted to N2K by the Seatalk-2000 converter. Both the Seatalk converter and the NK-80 are galvanically isolated and differential.

We have these exact conversion systems running on our boat for years without issue.

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Probably the best investment I made was replacing the old Raymarine 4000 iirc.. with a new Raymarine Evo.. the 9 axis accelerometer sensor has the autopilot turning the rudder as the boat slews through waves even prior to being off course.. it reacts like a human pilot..
Thanks for reinforcing this point. I've pointed out many times that today's AP's are completely different beasts compared to those just a few years ago, and can steer a boat through all conditions better than a human. It seems I'm rarely believed. Most of this increased performance is due to the significant advances in compasses, higher data rate GPS and wind transducers, as well as steering algorithms designed to use all of these data.

When we changed in 2010 from what was the top AP 10yrs earlier to a good consumer AP, I was shocked at how much better it was. When we changed boats 3yrs ago and put on a current AP and a 10hz wind, 30hz GPS, 20hz compass that also outputs heave data, and steering algorithms that incorporate all of this, the difference was noticeable again.

We never worry about broaching or overcoming the AP's ability to steer. If there are conditions where these could happen, we haven't encountered them yet.

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I see no advantage to the capability to steer to a coordinate. I am still very much involved in all sailing decisions... steering, trim, and watch keeping.
For example, motoring - particularly in a cross current. Yes, one can sit at the AP continually adjusting the course to meet a waypoint, but it is much easier to just set the AP to that waypoint and relax.

Your description of setting the heading line on the plotter to meet the COG to a waypoint is exactly setting the AP to the waypoint. I don't see much advantage of doing this manually (and continually making adjustment), and both ways require one to adjust sails and stay on watch. You might think you are active in the steering, but allowing an AP to partially steer is a strange line to draw between full AP steering vs. full hand steering.

One advantage of steering to a waypoint/route vs only to a compass is making a course change short handed. When steering to a waypoint, and that waypoint has been reached and the boat needs to go to the next, the AP alarms that it wants to turn to the next waypoint and one pushes the "OK" button, then one is free to adjust sails while the AP turns and locks onto the new course. No juggling tasks between setting the course and adjusting the sails.

Another advantage of having the ability to integrate a GPS (regardless of if it is used) is if the compass goes down, the AP can use COG as heading and continue to work. Otherwise, one has lost their AP.

Having wind integration opens up much more functionality and usefulness.

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I observe the track which will deviate from a straight course because of current and making leeway for example. But I can find the course which essentially steers the direct line... and yes over time I AM making some minor course corrections. I do this when sailing or trim... Sailing is an ACTIVE process.
Also key to how I navigate/steer with the AP is I see where the heading will take me... over hazards, thin water and so on. The GPS waypoint doesn't know what its course passes over.
I think the KEY word is that I am ACTIVE with respect to steering evaluating the chart and weather/sea conditions constantly and accounting for them. But the level of activity is minor... If there is a cross current in a few minutes I can see how the set course needs to be corrected... And observe is KEY... I need to consider traffic and make adjustments accordingly. A set waypoint ignores this. When a boat is crossing my path I often steer to its stern.. which changes as he moves across my path... The skipper can see that I am taking a decision to avoid a collision and not even pass in front of his bow.
A waypoint may be many miles away... and steering to one ignores the local environment.
As I mentioned I often enter waypoint coordinates and my instruments are providing data for that point relative to my present position.
So let's say I am moving in a strong cross current and the waypoint is 90°. I will turn the course dial and observe what is the COG is and make it 90°... I may actually be heading 100° but set to 90° by the current... So I can sail almost perfectly straight course (shortest) to my destination / "waypoint". Any typically I have to do a lot of "dodging" of boats... and that is no problem the way I use the AP. This shows the difference between the course line and the heading line.
View attachment 143543
Looks like I can pass safely between the buoy "15" and buoy "2". Track is light magenta line
I get it. It is exactly how things look when the AP is set to a waypoint. The only difference is that one is not continually making adjustments to the heading to maintain that course to the waypoint. Like I said, it is a strange distinction, and to me it isn't any more "active" than letting the AP continually make these changes.

When our AP is set to a waypoint, the COG and heading lines are also on our plotter. They overlap pretty closely, but one still sees what is happening. If you are on top of things with your system, the heading and COG lines would also be overlapped pretty closely. I don't understand why one would plot a COG over a hazard or thin water, nor how the heading line would show this where the COG line does not. The heading doesn't understand hazards anymore than the COG does.

If you were really serious about being "active", you wouldn't use the autopilot at all. Again, a strange distinction of where to draw a line there - and an imaginary line at that, since there really isn't any difference in activity beyond occasionally turning a knob a little bit, nor any difference in awareness of what is going on environmentally. Not sure why you think that setting the AP to a waypoint is like going below and taking a nap. It is more like not continually holding the jib sheet in your hand, and instead having confidence that the winch or clutch will hold it so you can walk away.

In your example above, the difference in AP operation would be that if something went pear shaped that required and diverted one's attention as those buoys were approached, the AP steering to a waypoint would safely steer through them, while the one steering to a compass might put the boat on the rocks.

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Mark... I do not continually have my hand on the dial and steer. I can steer that way through the mooring field to the fuel dock and then release the AP and do the "landing" manually. That sort of maneuver demand more helm turn than any AP can do.
Sorry, I didn't mean "continually" in that way. I meant it to mean making periodic manual course adjustments throughout the time the boat is sailing a course.

Don't know why you think other AP's can't do what you describe. That is exactly how we use ours. Our control head even has a turning knob on it, so it is just like using the wheel. Our previous one only had dodge buttons, but worked the same way.

By active I mean I am observing conditions and tweaking the AP heading accordingly or as needed. I can and often do enter a "choke point" ... beginning of a "channel" where boats are converging and emerging...usually motoring or motor sailing steering with the AP dial. I am evaluating the traffic so the actual entry waypoint is not THAT important... it's a channel and there are boats coming and going.... a good place to hand steer.
When we are steering to a waypoint, we are also observing conditions. Still don't see why you think this mode implies differently. I agree that choke points are a good place to hand steer, or to use the pilot in manner that is not steering to waypoint. In fact, it is pretty onerous to even attempt to make routes for the AP to steer through these types of transit areas - way too many points and situational considerations.

I often use an old track and follow it in many cases....no waypoint...it's a safe path... I turn my dial to "get on" the old track... which I can follow right to the mooring... or to the channel to the town dock. It's like manual steering... but using the AP dial and not the actual wheel.
Well you would just love a modern AP integrated to your plotter! For us, we just tell the AP to follow the old track. No need to touch the dial or wheel. Of course, if there is a lot of turning, the cross track error can sometimes reach 2 or 3 feet... ;)

Mark
 
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