Magnetic Variation Data Update

Magnetic Variation is calculated from a model that must be updated every five years. The current magnetic variation data in Navmaster expired 31st December 2004. Until such time as the new data is installed, Navmaster will be unable to calculate magnetic variation and will display a message "Magnetic variation data unavailable".

A new file, IGRF2005.dat, is now available for the period from 1 Jan 2005 to 31st December 2009 and is available for download. To download the file:

   1.  Type the following address - www.pcmaritime.co.uk/public - in your browser (or click this link).
   2.  You will see a list of files that are available for download.
   3.  Right click on IGRF2005.dat and select Save Target as...
   4.  If Navmaster is on the computer you have used to connect to the internet, save directly to C:\Program Files\Navmaster. Otherwise save to a temporary folder and copy to the computer used to run Navmaster.

Magnetic anomalies are often reported for specific regions of the world and these are usually printed on charts. This model cannot take into account the possibility or presence of magnetic anomalies.

For information on the limitations of this model please refer to http://www.ngdc.noaa.gov/IAGA/vmod/igrfhw.html

Another update, which will be valid for a further five years, will be required for calculations beyond the end of 2009.