Autopilot

[Gunni]

A couple of other things. In the past B&G was sail, Simrad power. Now they share the same course computers NAC2 or NAC3, same compass, rudder sensors, etc. I chose the Simrad AP44 control head as it is stand alone but the B&G requires a control unit and a second display.

Thanks Skip, I am leaning toward the Simrad AP as well since it has a familiar single control interface. Navico is recommending the NAC3 AP pack with the latest Precision9 compass.

Question: Were you able to configure a "Tack" function? I like to be able to have the autopilot command the helm while I sheet sails. It would be great if I could set a custom 92 degree tack angle.

 

[chuckwayne]

I'll second skipmac's comments on Navico - their tech support has been excellent and very good on my very technical questions (I also have a EE background). Before I bought my first navico system I spent an hour on the phone with them working out my network integration and conversion to N2K. When I hit them with a " how to interface some of my Raymarine gear" he said he didn't know but would find out and call me back - and he did! 1/2 hour later he called me with the data I needed. I'm still running my st400+ wheelpilot, but everything else is now Navico.

 

[colemj]

While I can't speak for the NAC3 specifically, the previous model AC42 allows one to set custom tack angles, as well as minimum angles when optimizing VMG. I suspect they did not remove those capabilities with the new model.

Mark

 

[skipmac]

While I can't speak for the NAC3 specifically, the previous model AC42 allows one to set custom tack angles, as well as minimum angles when optimizing VMG. I suspect they did not remove those capabilities with the new model.

Mark

NAC2/3 do allow the same. Not sure about the previous but when you activate the auto-tack the AP tacks smartly but initially to 5 degrees past the selected tack angle to allow the boat to come back up to speed then falls back to the desired course. Very cool.

This brings up a question I have about APs. I should have asked Navico when I was researching but was focused on other matters and forgot.

Seems like what all AP makers call the computer is the box that generates the power output to the drive. Then the box in the cockpit where you set course, etc the controller. My question, is all the programing and processing in the computer or does the controller also have intelligence (other than that required to send the basic course instructions to the computer) built in? The point being, would an upgraded controller add extra smarts to the AP or just a "better" interface?

 

[SG]

If the non B&G works the same as the B&G unit, I found that upwind one uses the apparent wind; and downwind the true wind as a reference angle.

I was surprised by this and tried the apparent wind when off the wind. That didn't work properly ply.

 

[SG]

Not in the control head. It's in the box for the units you are discussing.

You can have multiple control heads, and (sometimes) use a chart plotter/multi function display to provide the interface.

The NEMA sentences for the direction to the autopilot may come from other devices. (e.g., crostrax error, apparent or true wind, compass heading).

 

[skipmac]

Not in the control head. It's in the box for the units you are discussing.

You can have multiple control heads, and (sometimes) use a chart plotter/multi function display to provide the interface.

The NEMA sentences for the direction to the autopilot may come from other devices. (e.g., crostrax error, apparent or true wind, compass heading).

From discussions with Navico and the distributor, it seems like the NAC2/3 computers for B&G and Simrad are identical.

 

[Gunni]

I was told that all of the same AP functions were included in both B&G and Simrad. I am impressed by you EE types and your threshold for sorting out technology. I'm more of a "it's an appliance", which button do I push to make it do X.

 

[colemj]

NAC2/3 do allow the same. Not sure about the previous but when you activate the auto-tack the AP tacks smartly but initially to 5 degrees past the selected tack angle to allow the boat to come back up to speed then falls back to the desired course. Very cool.

And if you turn on "optimize VMG", it will tack, then slowly move about close to the wind optimizing VMG.

As I mentioned before with the Simrad, it uses apparent wind upwind and true wind downwind (although as you found out, one can change that behavior) - which makes sense. It also can be set to automatically prevent a jibe should the true wind angle change when deep downwind. Actually, that is its default behavior.

Mark

 

[Gunni]

I could have read tech manuals for 2 eye-glazing hours and not learned what you guys revealed in a few concise comments. Thanks. Is this a great forum, or what!

I will have my tech guy do the install and he tells me that he can make my existing Ray wind instrument (speed / direction) integrate with the Navico AP computer to provide wind data. Apparently it just requires a "converter".