With this Leg we introduce Wes Murfin who is providing the cruise with
Silicon Sea Cruise charts. Please DO NOT contact Wes with questions about
the charts. Post to the List.

In Wes's words:

The data for these charts comes from the map viewer program at Xerox
PARC (http://pubweb.parc.xerox.com/map).  Capturing and massaging the images
to a nautical chart format was a tedious and initially frustrating process
but I am pleased with the results.  For free charts off of a 9-pin dot
matrix printer they are good enough to plot courses and LOPs.  The fixes and
positions may not be as accurate as calculated values but should be good
within 2 to 3 miles. That may not be bad for celestial navigation from a
small boat in blue water.  These are not true Mercator projections but more
similar to plotting sheets with a fixed latitude scale.  As a consequence
the latitude range is limited to a maximum of aproximately 4 degrees.
Longitude range is limited only by the paper size which needs to be 8.5 by
11 inches if these are to be generally distributed.
****************************

Sight Reduction and DR
Dead-Reckoning problem     Leg 14  050696   Test your knowledge!
----------------------     ------  ------   --------------------

See addendums to the NOTE section for these problems.

At 02-00-00ZT, 13/05/96 DR(37 58.9'N  11 32.9'E) we set the Walker
Patent Log(0.0) out after we lost the Knotmeter. The log now reads
16.0 miles. We are on a TC of 105.0 at 8.0 Kts. Var 1dW, Dev
|4dE. Time 03-00-00 GMT.


1)  What is our DR position?
    Based on this DR what is the time of the start of Morning
     Nauitcal Twilight?
    What is the time of Sunrise? 
--  --------------------------------------------------------------

We take the following three body sight. We choose the bodies for an
Azimuth spread and Polaris because we know it so well and is easy for
us to find.

     Body           GMT Time            Hs             Zn

     Polaris        03-10-21            37d 47.5'      000.9d    
     Rasalhague     03-11-40            54d 58.0'      231.0d           
     Altair         03-14-47            60d 29.8'      168.0d          

2)  What is the FIX and Dist Off using 03-14-47 GMT for plotting?
    What other navigation check does using Polaris provide?
--  -------------------------------------------------------------

3)  What is the reasoning for selecting the order of the bodies for
    the MNT sights?
--  ---------------------------------------------------------------

4)  Our compass bearing when sighting Polaris was 003.9d. Based on the
      current Var 1dW and Dev 4dE is this correct?
    What is the total Error?
--  ------------------------------------------------------------------


Our morning sights are taken and plotted. We have a Knotmeter inoperative
and we will be a tad thirsty and smelly when we get to Eygpt. The skipper
decides that we need to make for a port and make repairs before Eygpt. A
look at the chart shows only three places, small towns on the south coast of
Sicily, Tunis, of which we know nothing, or Malta, a well known yachtsman
harbor, that lays ahead. So, Malta(35d 50.0'N  14d 30.1'E), it is.

5)  What is the TC and Dist to Malta?
--  ---------------------------------

6)  At 8 Kts how many hours, rounded to the nearest minute, are we from
    Malta?
--  -------------------------------------------------------------------

7)  Malta is 258 meters high at what Dist in nautical miles, should we be
    able to sight it on the horizon?
--  --------------------------------------------------------------------

8)  At our current speed of 8 Kts at what GMT date and time can we expect
    to sight Malta on the horizon?
    What ZT?
--  ---------------------------------------------------------------------

NOTE:
Lat & Lo = XXd XX.X', Date=DD/MM/YY, HE 8 Feet, Index correction -.2', Time
hh-mm-ss in UTC/GMT. Silicon Sea is a medium displacement sailing vessel, 40
Feet LOA. 38 Feet LWL; Cutter rigged. Looks a lot like a Mason. Can tack to
45d. Dist to Horizon: Nmi = SQRT HE@mtrs x 2.07; Nmi = SQRT HE@ft x 1.17.

PLEASE respond with your results and thinking on these exercises to the
NAVIGATION list at large. If you have questions or problems, A lot of folks
on the list are knowledgeable and willing to help. Any questions or doubtful
areas will be responded to promptly. Let us hear from you soon!

Good Navigating!

   -=The Navgation List Working Group=-

        Peter Smith  - psmith@wellspring.us.dg.com
        Ron Legere   - ronald.legere@yale.edu
        Tony Severdia- anthonys@ix.netcom.com
        Dan Hogan    - dhhogan@lightside.com
       
