Seatalk NG Demystified

HMT2

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Mar 20, 2014
899
Hunter 31 828 Shoreacres, TX
I recently installed a Raymarine EV100 Wheel pilot on my 1983 Hunter 31, the original ST 4000 finally gave up the ghost and went to "Iron Mike" heaven. I had an existing N2K network (also called "Devicenet" who knew?) with a wind instrument, Garmin 541s , Simrad RS35, and Ikommunicate on the N2K network. All worked flawlessly together. I was very concerned about adding "Seatalk NG" to the mix. But with few wheel pilot options I went forward. Here is what I learned from talking to a Raymarine tech and installing the auto pilot. Sea Talk NG (do not confuse with previous versions is Seatalk) is a N2K network with an extra wire and a proprietary connection system.
You have to use a Seatalk NG cable to plug into the Raymarine instrument, after that you can use a field installable Devicenet connector or use a Seatalk NG to Devicenet adapter cable (stunningly enough both similarly priced). N2K always has five wires the same color, a bare wire, blue, white red and black. Though the color of blue can vary, it's still blue. Seatalk NG has a sixth yellow wire for talking with previous Seatalk versions. When using the Devicenet field installable connectors just cut the yellow wire off and do not attach it. I used these connectors to plug the Raymarine instrument for the auto pilot into my existing N2k network and it all worked like a champ. The Raymarine components that were supposed to draw power from the network did just as the were supposed to and everyone talked they were supposed to.

So don't be afraid to cut the ends of those Seatalk NG cables! Here is a screenshot of a cut Seatalk NG cable and the field installable Devicenet male connector and the adapter cable. Poster does not necessarily endorse these vendors, they were handy for what it's worth riggersbench.com has some good information.
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Sep 23, 2009
1,475
O'Day 34-At Last Rock Hall, Md
Thanks for the tip. This is all new to me and I have never been able to find a good primer about it. Is N2K the same as NMEA2000? What does the auto helm tell the chartplotter? I have both and don't know what they would be interconnected for.
 

BarryL

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May 21, 2004
1,000
Jeanneau Sun Odyssey 409 Mt. Sinai, NY
Hello,

Yes, NMEA2000 and N2K are the same.

If you have your plotter and autopilot networked together, the plotter can give the AP a waypoint to steer to. If your AP and wind instrument are connected then the AP can steer to a wind angle. If ALL your instruments are connected (and relatively new), then the plotter will have true and apparent wind. The AP will be able to steer to a heading, wind angle, or waypoint. If your plotter and AP are from the same manufacturer, the plotter may be able to drive the AP directly.

In reality, this isn't that big a deal. My previous boat (O'day 35, same boat as your 34) had all stand alone instruments. My current boat has all networked instruments. With the O'day, if I was trying to get from point A to point B, or follow a route, I would use the plotter to provide a heading to the destination. Then I would activate the AP and adjust course until I was going in the right direction. Every now and then I would have to adjust my heading a little to stay on course. With the new boat I select the waypoint on the plotter and then ROUTE to it. On the AP all I need to do is press the 'track' button and it will get the heading from the plotter and steer the boat there. If the current, wind, or anything changes, the plotter provides updated info to the AP and the AP always stays on course. Again, not that big a deal but nice to have. Of course you need to keep watch, be aware of your surroundings, blah blah blah.

Barry
 
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HMT2

.
Mar 20, 2014
899
Hunter 31 828 Shoreacres, TX
NJlarry,
Happy to share what I learned. N2K, NMEA 2000, and Devicenet are different words for the same network. When buying instruments, ensure that they work with NMEA 2000, not all do yet. I echo what Barry wrote, he is spot on.
 
Sep 23, 2009
1,475
O'Day 34-At Last Rock Hall, Md
Thank you both for the clear and detailed descriptions.
I guess for me it's as Barry wrote, " not that big a deal ". I just steer till the chartplotter, a Lorance elite 5 hdi, shows the bow aligned for the nav aid and hit the auto button on the AP. Usually the only need for a course change comes from passing stink potters. At least now I understand what it's about.
 
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HMT2

.
Mar 20, 2014
899
Hunter 31 828 Shoreacres, TX
Thank you both for the clear and detailed descriptions.
I guess for me it's as Barry wrote, " not that big a deal ". I just steer till the chartplotter, a Lorance elite 5 hdi, shows the bow aligned for the nav aid and hit the auto button on the AP. Usually the only need for a course change comes from passing stink potters. At least now I understand what it's about.
NJLarry,

I've been sailing with my new auto pilot now for about six months. I mostly single hand out in Galveston Bay and my ap being able to talk to my gps is like going from a 70's VW Bug to a current Audi.
It is so easy to raise and lower my main by myself. While motoring, I just have the ap hold it 0 degrees into the wind. Being able to sail to a specific waypoint is helpful but the best part is the ap being able to hold specific wind angles.
 
Sep 23, 2009
1,475
O'Day 34-At Last Rock Hall, Md
Good to hear how well it is working for you. Now that I know that I can cut and splice the cable means that I can someday connect the auto helm to the wind instrument both of which are on either side of the binnacle.
Meanwhile I'm lovin my 84 VW bug.