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[imported_QCR]

Can someone please explain a simple way of working out variation on a chart. I have friend doing a course and all the explanations in the books seem to make it more complicated that it probably is.

Thanks

[seatime]

Variation on a chart?

can you be a bit more specific on what you want to know about variation (magnetic)?
do you want apply variation as an error, convert to True and vice versa for laying off courses?

If using an Australian Hydrographic Service chart, the mag variation for a certain area is printed on the compass rose that is closest to that area. Variation is the angular difference (an arc) between True North & Magnetic North, measured in degrees & mintues. The common Mercator chart is drawn with lines of latitude & longitude appearing as straight lines - lines of longitude show us where True North & South is, lines of latitude tell us True East & West. A magnetic compass points to Magnetic North, East, South & West. The difference between the positions of True and Magnetic North is the Variation.

There is a lot more to it of course but unfortunately there isn't enough time or space on a forum such as this to adequately explain the poles, lines of magnetic force and influence on a magnetic compass, plus True North and gyroscopes.

regards
Steve

[Roughasguts]

Yes theres Variation which is for example a map over Sydney could say.
Variation 10 deg East meaning to convert from a True heading to a Magnetic heading of say 120 deg true to get a compass heading all you have to remember is.

Variation East Magnetic Least, In this case 120 deg True on the chart to get
Magnetic or compass heading is minus 10 deg the variaton therfore compass heading is 110 Magnetic.

Variation West Magnetic Best, same thing just add the variation

Then theres deviation, that's compass error, theres a error card written up near the compass for that.

Get back to us when your ready for Track errors and closing angles to make your track made good. Basically it's the old 1 in 60 rule great stuff it is and much more
satisfying than GPS.

[Marlin_Mike]

The variation was 11deg 24min in 1999 decreasing by 0.01 per year

Mike

[Roughasguts]

The variation was 11deg 24min in 1999 decreasing by 0.01 per year

Mike
For where Sydney ? could be about right think it was 10.5 deg East 13 years ago.

[Noelm]

roughas has got it prety well right, I guess you are doing maybe some sort of correspondence course?? if so, Local coastal Patrols (VMR) Yacht Clubs and the like ,do coastal navigation courses from time to time, very informative to attend one if you do not have a "Teacher" to fully explain it face to face, it is not hard, BUT you need to fully understand it and get it right every time.

[imported_QCR]

Thanks to you all,

The answeres explained it well, we just neede something that made it easy to remember, The East is least Rhymn fits the bill
thanks again

[Roughasguts]

No problem, there will be more questions it gets harder.
Feel free to ask.

Cheers.