Technical data
Guide to compasses
What is magnetic declination (variation)?
Magnetic declination is the difference in degrees, between Geographic North (to
which the maps meridians are directed) and Magnetic North (to where the com-
pass needle is pointing). It varies, depending on where you are in the world and
can be found on most maps. Eastern declination means that you shall subtract
the amount of the declination from the bearing obtained from the map to get
a true compass course. Western declination means naturally that you should
add the declination to the bearing. With some Silva compasses (such as model
Ranger 15 TDCL, Expedition 25 TDCL-E or the Voyager series) you can compen-
sate for the declination .
Does my compass work anywhere in the World?
Yes, the only thing you might consider is the fact that the compass needle can
dip/tilt if you travel far north or south from the area in which you bought the com-
pass (and for which area it is intended to be used). Normally this does not affect
the accuracy but for world wide travellers we recommend the Voyager series,
which due to its construction/balancing of the needle can be used in most areas
without affecting its performance.
Why does my compass show the wrong direction when I am in the car?
Because of deviation, the deection of the compass needle from Magnetic North,
by a magnetic eld other than the earth’s magnetic eld.
One must always be aware of that this can happen. Magnetic elds exist near
knives, scissors, electronic instruments including radios, metal fences, wea-
pons, tins, some rings and watches, spectacle (especially the hinge screw) and
vehicles. When using your compass – try to stay clear of strong magnetic elds
for the best accuracy.
How do I make sure that I care for my compass in the best possible way?
Try to store your compass away from extremely strong magnetic elds such as
strong magnets, loudspeakers, etc which in extreme cases can demagnetise the
compass needle. Avoid giving compasses hard knocks, and if needed clean the
compass in fresh water.
What shall I think about before leaving home?
Check the polarity of the needle, the general condition of the compass and that
the compass functions correctly so that you can be sure that you get the most out
of your Silva-compass.