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Topic starter
April 16, 2018 2:54 am
On an offshore cruising sailboat we find it impossible to have a new Simrad NAC-3 autopilot computer see or read the wind information from a new Airmar WX220 weather station transducer. Both units are on the N2K backbone. The autopilot is controlled with a new Simrad AP-44 display. The AP-44 operating on the same N2K backbone properly displays the wind data and all of the other data output from the Airmar WX220. When the NAC-3 is put in “wind” mode an alarm on the AP44 states “AP wind data missing”.
Simrad technical support has over the last few months suggested numerous settings and items to check and confirm; none have solved the problem. Simrad is now stumped and states that it does not possess an Airmar WX220 and therefore is unable to investigate further. Airmar outputs wind data PNG 130306 and Simrad NAC-3 looks for wind data PNG 130306!!! The purpose for the Airmar installation is for the AP to steer the boat by the wind direction.
Anyone have any experience with this or any thoughts?
April 16, 2018 4:35 pm
Do you have anything on the boat capable of logging the PGNs sent by the WX220. Armed with that data I would think you and Simrad could get much further in figuring out what the AP-44 doesn't like about the incoming data.
Ben
Publisher, Panbo.com
Steve Mitchell reacted
Topic starter
April 16, 2018 6:42 pm
I had ordered an NGT-1 and it should arrive today. It should arrive today; I'll have a look at the data.
BTW,Another boat is using a Maretron weather station with the same Simrad AP and it appears to function properly.
Steve Mitchell reacted
July 31, 2018 3:43 pm
Could be the configuration of your WX220 and AP44, around using Apparent vs True wind.
Do you have the PC software (weathercaster?) and interface to configure a WX220?
There are multiple choices on the WX220 as to which PGN to send wind data and how often.
The AP44/NAC-3 has options to sail by the wind in either TRUE or APPARENT or AUTO (it chooses based on wind angle). Perhaps your autopilot is looking for TRUE wind and your WX220 is only providing apparent wind. Solution is to change the autopilot to sail by the apparent wind (or) see if your instruments can be setup to calculate the true wind (from apparent & stw) and rebroadcast on the N2K (or, the option I don't like) set the WX220 option to output apparent and true wind (which was the default on the PB200, causing Raymarine users issues, maybe they changed the default on the WX series)
From the AP44 Manual:
Sailing (NAC-2/NAC-3)
Note: Sailing parameters are only available when the boat type
is set to Sail.
• Wind mode: Select what wind function the autopilot will use
when in wind mode
- Auto:
If TWA is <70º: Wind mode will use AWA
If TWA is ≥70º: Wind mode will use TWA
- Apparent
- True
Steve Mitchell reacted
