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Next Nexus Question


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#1 Fig 11

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Posted 14 October 2013 - 12:28 AM

I’ve recently installed a new set of Nexus gear including an NX wind and sea data and an NX 2 multi.  Gear’s all been calibrated by the rep.  All’s good until I look at our true wind speed and wonder why we’re getting the sheet kicked outta us upwind when the true wind on the instruments is less than 10knts.  I’ve compared the TWS on the instruments to that on the laptop.  The two are quite different, with the amount looking to be the 1.7 factor for the double fin masthead unit and the 0.5m/s offset that the wand needs to get going.  Both the instrument and the laptop show 1.7 calibration factor.  The laptop shows the offset as 0.5m/s, but I can’t see where the same is set in the instrument.  Anyone come across this or, better yet, got a solution?

 

Cheers

 

 



#2 allen

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Posted 14 October 2013 - 12:36 AM

I have no idea but this calculator might be useful

http://l-36.com/polar_calculate.php

 

Allen



#3 galacticair

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Posted 14 October 2013 - 08:00 AM

Are the instruments still in m/s? I remember being surprised at the wind speed numbers being output after a full nexus reset of my nexus server - turns out the nexus instrument display default is m/s... That would also account for - 2.0x difference va laptop (not the 1.7x calibration factor, which is fine). Easy to fix this to kts display in the instrument calibration settings (MultiDisplay calibration functions - see the manual for the details)

#4 Fig 11

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Posted 15 October 2013 - 01:29 AM

Hi Allen

 

While not what I was after, that's pretty cool, thanks.

 

Galacticair, so simple, it my even be right!  Never even tough to check that, but seems well worth a look.

 

Cheers

 

 



#5 ctsailor55

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Posted 16 October 2013 - 02:47 PM

Your 1.7 calibration factor is corect for the twin fin vane. If you compare m/s speed and knots, m/s is almost (but not quite) twice the speed reading of knots. Your wind speed calibration offset may be too generous especially considering the system is new. Try zeroing out the offset to nil. I have zero offset in my system and usually don't factor one in on systems I've installed or worked on.




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