On Fri, 16 Dec 2005 16:28:49 -0600, Skipper wrote:

Here's the situation: You're 100 miles offshore and bailing to the
liferaft. You've become disoriented and have lost your bearings. You
reach for the GPS-12 and find it's DOA. Among your options is the sun
compass. Do you know how to make and use one?
==========================================
From:

http://www.griffithobs.org/IPS%20Pla...IPSViking.html

The sun compass. This instrument draws on the fact that the sun´s
shadow from the tip in the middle of a disk describes different
hyperbolas at different times of the year. When you have the hyperbola
representing 62° and the four weeks around summer solstice, you don´t
have to know the time of the day in order to find the general
directions. All you have to do is rotate the disk until the shadow of
the tip falls on the hyperbola, and the general directions are given
with an accuracy of a few degrees. One of the ingenious things about
navigating with this instrument is that if you should choose the wrong
gnomon curve and get a course that is a little too much north in the
morning, this will be corrected in the afternoon by a slightly south
bound course-and your average direction will be correct.
============================================

There's another old trick with an analog wrist watch where you put a
matchstick (or similar) vertically over the middle. Rotate the watch
until the shadow falls along the hour hand (that's the little one).

North is roughly in the direction of 12 o'clock. Works best spring
and fall in the northern hemisphere.

"Wayne.B" wrote:

The sun compass. This instrument draws on the fact that the sun´s
shadow from the tip in the middle of a disk describes different
hyperbolas at different times of the year. When you have the hyperbola
representing 62° and the four weeks around summer solstice, you don´t
have to know the time of the day in order to find the general
directions. All you have to do is rotate the disk until the shadow of
the tip falls on the hyperbola, and the general directions are given
with an accuracy of a few degrees. One of the ingenious things about
navigating with this instrument is that if you should choose the wrong
gnomon curve and get a course that is a little too much north in the
morning, this will be corrected in the afternoon by a slightly south
bound course-and your average direction will be correct.

Another simple method:

http://tinyurl.com/aub5l

--
Skipper

On Fri, 16 Dec 2005 19:43:05 -0600, Skipper wrote:

Another simple method:

http://tinyurl.com/aub5l

===============================

Yes, when lost at sea without a compass,

find a tree,

and see which side the moss is on.

Perfect.

Wayne.B wrote:
On Fri, 16 Dec 2005 16:28:49 -0600, Skipper wrote:


Here's the situation: You're 100 miles offshore and bailing to the
liferaft. You've become disoriented and have lost your bearings. You
reach for the GPS-12 and find it's DOA. Among your options is the sun
compass. Do you know how to make and use one?

snip
There's another old trick with an analog wrist watch where you put a
matchstick (or similar) vertically over the middle. Rotate the watch
until the shadow falls along the hour hand (that's the little one).

North is roughly in the direction of 12 o'clock. Works best spring
and fall in the northern hemisphere.


No, think what happens at 6AM :-)

Its actually something like point the hour hand at the sun and SOUTH is
half way between the hour hand and 12 o'clock (or North in the Southern
hemisphere).

--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
[at]=@, [dash]=- & [dot]=. *Warning* HTML & 32K emails -- NUL:
'Stingo' Albacore #1554 - 15' Early 60's, Uffa Fox designed,
All varnished hot moulded wooden racing dinghy.

On Sat, 17 Dec 2005 01:53:14 +0000, Ian Malcolm
wrote:

Its actually something like point the hour hand at the sun and SOUTH is
half way between the hour hand and 12 o'clock (or North in the Southern
hemisphere).

============================

What ever works for you. What I do at 6:00AM is roll over and try to
get some more sleep. If that doesn't work and I still want to know
where east is, I look to see where the sun is coming up.

Wayne.B wrote:

What ever works for you. What I do at 6:00AM is roll over and try to
get some more sleep. If that doesn't work and I still want to know
where east is, I look to see where the sun is coming up.

My bed faces the east, with a large window on the east wall, I have no
problem getting up and not knowing which way east is.

seeing the road in front of my house runs dead north/south, and I go to
work by turning right at the end of my driveway, I have no probllem
knowing which way north is.

Concerning sailing? I don't need to know which way north is, because I
only go to a large S. Illinois lake.