The error of 2 degrees is *statistically insignificant* when using a
compass for marine purposes. Most sigtings will be less than 2 miles.
2 degrees error will be sin 2 = 3.5%. Thats 350 ft error in 2 miles
or 10-15 boat lengths!!! .... then add error for the boat while
pitching, rolling, yawing, set/drift, leeway, compass error, local
magnetic 'anomalies', etc. For short courses, 5-10% error is within
'normal limits' ............. then use your 'head' and your
**depthsounder** to keep a DR track.
;-)


In article , Chris
Doubleday wrote:

I am new to the world of compasses and sailing. My wife recently
purchased a sighting compass as a gift for me when sailing/cruising.
It is a traditional sighting compass with needle and mirror (Suunto
MC-2G-Global). I am more accustomed to using a compass with a compass
card and view finder. I suspect it will be difficult to get an
accurate bearing with the MC-2G-Global on a moving boat due to having
to adjust the bezel while sighting the landmark. Is this the reason
for the different design (card and finder) of the KB-20? The
MC-2G-Global does have a global needle which I underatdnw should help
with some of the pitching and rolling that will occur on a boat, but
it still seems like an error prone process, especially when trying to
get multiple simultaeous fixes as when dead recconing. The accuracy
is noted as 2 degrees, which I imagine is only attainable in the best
of conditions. Any opinions / experience with this sort of compass in
a cruising environment?

I agree with Rich and will add that if your way off on a bearing you are
likely to know it or be able to guess at it so you can shoot it again.

If you are really pitching and rollling a lot you may have to make multiple
attempts but you will get it.

Finally you will get better with practice. People have been taking accurate
(enough) bearings from moving decks for hundreds of years.




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