Very Good Bob. Now how can you use that info to navigate?

Joe

If you accurately know the time and roughly where you are you can estimate
your position on the surface of the earth by measuring angles from the
horizon in a given direction to known celestial bodies and the angles
between celestial bodies. Since the earth is not a sphere, one must know
roughly where one is to include an approximation for the ellipsoid surface
of the earth. Once one has a series of these angular measurements,
calculations are made and tables are consulted. Eventually, one arrives at
an estimate of position. This method has been in use for hundreds of years.
I could break out my old Dutton's from the Naval Academy and give you a
refresher if you want. It's been years for me.

Another method, used in space craft and ICBM's, has similar geometric
calculations except that the surface of the earth is no longer used as a
reference point. In fact, the reference point may be changing constantly in
radius. Typically in these astrodynamical calculations three reference stars
are used along with inertial navigation data and other types of
radiolocation data. The results of these input are Kalman filtered (weighted
time average) and the resultant intersection of the locus of the
navigational error plots from each system yield location. Typically, the
missile is whizzing along at 17,000 mph at altitudes up to 60 miles.

Amen!



..com wrote in message
oups.com...
Very Good Bob. Now how can you use that info to navigate?

Joe

a) where you are
b) where you are going


"For navigation purposes what is the most
important thing to know when you get in
your lifeboat ?"

Very Good..... you get the coveted asa point on that one.

Joe

In article .com,
Joe wrote:
Very Good..... you get the coveted asa point on that one.

Joe


Let me claify then... I'm in a lifeboat and it's dinner time. :-)


--
"j" ganz @@
www.sailnow.com

Joe wrote:
For navigation purposes what is the most important thing to know when
you get in your lifeboat?


To not get into it at all, until you have to climb up to get in.

DSK

How about your eprib, last known position, meteorological data [wind
direction/velocity etc] and knowledge of the local currents.... add
coastal chart knowledge for Bob and the Sea Tow telephone number for Binary
Bill.


CM

"DSK" wrote in message
...
Joe wrote:
For navigation purposes what is the most important thing to know when
you get in your lifeboat?


To not get into it at all, until you have to climb up to get in.

DSK

Joe,

In this day and age, A smart seaman is a hell of a lot better staying in
the area of the sinking. The range of aircraft and the locating ability
of radio signals makes rescue easier if they don't have to chase you all
over the Ocean



http://community.webtv.net/tassail/ThomPage

Thats fine and dandy if you have a working epirb, VHF, sideband, satt
telephone. Which every wise ocean sailor should have. However as you
know things fail at the wrong times and you need to have the largest
tool chest of knowledge possiable to get out of a fix IMO.

Call me old fashion for not trusting all the new gadgets and relying on
myself .

Joe

Joe,

I hear what you're saying but charts, tables, watch for GMT seems like a
larger load than a espirb & Sat. phone.

Even if you escape with nothing; sitting as close to last reported
position is still better than wandering the ocean. IMHO.




http://community.webtv.net/tassail/ThomPage