VicMap Declination/ Variation

[meo]

Hi all, I'm new to this forum but wondering if you may be able to offer some assistance?

I have just picked up a new VicMap and the Grid magnetic declination shows at 0 11' 44", Grid magnetic angle 0 11' 08" . I have looked up magnetic declination for the area and it shows its at 11 55' degrees.
Isn't that meant to be displayed on the map?

I am trying to work out magnetic variation to convert grid to magnetic. If the declination shows 11 55' in that area (after an internet search), shouldn't the map say the same (or close to as the map was produced in 2009)? Or do I disregard the map and use 12 degrees (11 55' rounded) as my variation?

A bit confused as other maps I have used show the variation and I just adjust for years since the map was produced.
Any assistance would be greatly appreciated.

Attachments

[madmacca]

The wording on the map says the variation was 11 44 in 2009, and increases by 1 min/year, so on that basis would be 11 50 now.

It takes a fairly skilled navigator to follow a bearing within 5 DEGREES of accuracy. 5 minutes is immaterial.

[Mark F]

Please note that the Magnetic Declination shown on the map is 11 minutes 44 seconds, not 11 degrees 44 minutes. Approximately 1/5 of a degree which may as well be ignored. You cannot navigate to that level of accuracy.

[meo]

Thanks for the responses madmacca and Mark F.

Did I read this correctly that I got two different views on how to read it?

So madmacca you are saying that I should subtract 11.5 when I convert to Magnetic bearing on compass?

Mark F, is the map showing that as its so recent it has been adjusted for magnetic variation already. So the variation of 11 minutes 44 seconds equated to .18 of a degree so should be disregarded when converting grid to magnetic?

Thanks for the responses

[Mark F]

The Magnetic, Grid and True north are effectively the same in this location and this will not change in any meaningful way over the next 50 years unless we get a major upheaval such the magnetic poles reversing (this does happen).

[meo]

Thanks Mark F, no need for math or a compass with magnetic declination adjustment then. Cheers

[madmacca]

Oops, Mark F has sharper eyes than me. Mine jumped a cog and read it as 11 degrees.

Mark F is right - magnetic declination is so small in this map location that it can be ignored for bushwalking navigation purposes.

[neilmny]

VERY IMPORTANT - Hi folks the declination shown on the map of 11 minutes 44 seconds on this map is an error it is indeed 11 degrees 44 minutes. I contacted Vicmap about two years ago about this and the future printings will be corrected.

To be 100% sure feel free to contact Vicmap. From memory I emailed them. I check if I kept a copy and will forward if I have it still if needs be.

FOLLOW UP - I checked for the email but can't find it ................ email your query to info@dse.vic.gov.au which is the email address shown under "FEEDBACK" on the info panel.

[meo]

Neilmny that makes perfect sense. Explains why I was so confused even after checking a web site to show special mag ventilation in that area. I'll investigate further when they reopen next week.

Thanks to all for the replys

[Lophophaps]

In the early 1980s I bought a Silva 15T compass, the one with a sighting mirror. The 15T has a neat feature where the magnetic declination can be set so that all bearings are true, not magnetic. I set this the wrong way, and wondered why I was out by about 20 degrees. Quiet, genius at work. Since then the declination has been on 11 degrees and is not changed unless walking in a place that has a declination that varies significantly from this. When walking in trackless bush using the compass I know that it's very hard to keep on a straight line, and I hope that the variations will cancel. Features are used extensively, for sighting on, as handrails or to aim for offset, like a river.

[meo]

Just wanted to thank everyone for their input. It all makes sense now......I was lead a stray from VicMap from the start.

neilmny - thanks for putting me onto this map error. I wouldn't have guessed that the map would have been printed with incorrect information! Save a lot of heartache!

I received an official response from VicMap today:
"Yes, it is an error on the sheet, and the declination is 11 degrees 44 minutes.
I have spoken to the person who creates these maps and he is making sure the next edition will have the correct values.

Regards,
Chris Egan

Chris Egan | Senior Technical Support Officer | Application Services
Corporate Services | Department of Environment, Land, Water & Planning
Level 13, 570 Bourke Street, Melbourne 3000
T: 03 8636 2322 | F: 03 8636 2813 | E: land.channel@depi.vic.gov.au"


Thanks again everyone!