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?

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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Regardless of the ultimate accuracy, a card will be much easier to use
on a boat than a needle. The card can be damped easier so it will
settle faster.

As an example of the extremes, I have a K&E pocket transit accurate to
..5º. It works great when I am walking off property lines but is
impossible to use on a boat. OTOH, I can get usable bearings within 2º
or so from my W&P puck in seconds.

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?

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

I use a Silva Ranger TD... had it for 40 years, works on land, sea, and have
used it in small planes for fun/checkup navigation. With use you become
adept at quick sightings lining up the needle/mirror/object ....accuracy is
certainly as good as most card compasses, maybe better. Global/zoned needle
is not really relevant with regard to accuracy and the movement of the
observer...go to the Suunto and or Silva site to get an understanding of
what global/zoned needle means.

"Chris Doubleday" wrote in message
om...
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?

On second thoughts after posting this message, I realised there is possibly
an issue as to reliability at sea, particularily regarding salt and the
mirror.

My Silva has been a constant companion over many years, hanging on a
lanyard between my sweaty breasts on bushwalking, skiing, and sailing
trips...so far the mirror is fine. The mirror is in fact travelling far
better than the mirrors on my sextants! There is however corrosion of the
alloy cover over the mirror....but a bit of work with a toothbrush and soap
gets the green **** off from time to time. After 40 years the 4 tiny rubber
feet that hold the silva steady on a chart have rotted away, but I am going
to write to Silva to complain about that one.

"Glendon" wrote in message
...
I use a Silva Ranger TD... had it for 40 years, works on land, sea, and
have
used it in small planes for fun/checkup navigation. With use you become
adept at quick sightings lining up the needle/mirror/object ....accuracy
is
certainly as good as most card compasses, maybe better. Global/zoned
needle
is not really relevant with regard to accuracy and the movement of the
observer...go to the Suunto and or Silva site to get an understanding of
what global/zoned needle means.

"Chris Doubleday" wrote in message
om...
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?