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?

--
Skipper

"Skipper" wrote in message
...
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?

--
Skipper

In this scenario what good is any sort of compass going to do for you
Skipper?

Do you plan on trying to paddle a life raft 100 miles to shore against a
current?

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?


Yes. Do you?

To make an accurate sun compass requires an almanac and a
watch. With a protractor, you could improvise if you had a
good idea of the current declination of the sun.

It's based loosely on the concept that the sun rises in the
east and sets in the west, and at local noon will be either
directly south or directly north, depending on which
hemisphere you're in. With a protractor, you can draw angles
on a card (or directly on the deck) and interpolate
direction between sunrise and sunset.

Now, can you do the same thing for the moon?


Fair Skies
Doug King

I look at the sun in the AM and know that is the east. In the PM I look at
the sun and I know that is west.

I am close?


" JimH" wrote in message
...

"Skipper" wrote in message
...
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?

--
Skipper

In this scenario what good is any sort of compass going to do for you
Skipper?

Do you plan on trying to paddle a life raft 100 miles to shore against a
current?

DSK wrote:

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?

Yes. Do you?

To make an accurate sun compass requires an almanac and a
watch. With a protractor, you could improvise if you had a
good idea of the current declination of the sun.

It's based loosely on the concept that the sun rises in the
east and sets in the west, and at local noon will be either
directly south or directly north, depending on which
hemisphere you're in. With a protractor, you can draw angles
on a card (or directly on the deck) and interpolate
direction between sunrise and sunset.

You may remember the incident about a year ago where a fellow on the
West Coast lost all power and drifted for weeks off the Mexican coast
because he'd lost his bearings and had no idea where North was.
Knowledge of the sun compass method would have allowed him to ID North
and sail quickly to shore.

The point of this thread is to remind us of the easy to learn sun
compass skill for determining North.

--
Skipper

Harry Krause wrote:
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?

--
Skipper



Why would such a situation be of any concern or interest to a drygulched
wannabe sal****er boat like you, stuck forever in Derby, Kansas?
You could spin yourself dizzy and you'd still be within spitting
distance of Wichita.

BTRW, whatever happened to your oft-announced plan to leave Derby, move
to the coast, buy a long-distance trawler, and ply the oceans?

Lotto ticket didn't pay off?



He's gotta keep those dreams alive. When they're gone...what's left?

"Skipper" wrote in message
...
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?

--
Skipper

check the backup gps first

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

"Skipper" wrote in message
...
DSK wrote:

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?

Yes. Do you?

To make an accurate sun compass requires an almanac and a
watch. With a protractor, you could improvise if you had a
good idea of the current declination of the sun.

It's based loosely on the concept that the sun rises in the
east and sets in the west, and at local noon will be either
directly south or directly north, depending on which
hemisphere you're in. With a protractor, you can draw angles
on a card (or directly on the deck) and interpolate
direction between sunrise and sunset.

You may remember the incident about a year ago where a fellow on the
West Coast lost all power and drifted for weeks off the Mexican coast
because he'd lost his bearings and had no idea where North was.
Knowledge of the sun compass method would have allowed him to ID North
and sail quickly to shore.

The point of this thread is to remind us of the easy to learn sun
compass skill for determining North.

--
Skipper



He could not find his way to an Island 26 miles away, that can be seen from
the mainland. He could have looked at the sunrise and figured out which way
the closest land was. And he is going to be able to improvise a compass?