Sight Reduction and DR
Dead-Reckoning problem     Leg 13  XXXXXX   Test your knowledge!
----------------------     ------  ----------------------------

On 12/05/96 we are at DR(36d 13.9'N  10d 54.4'E), on a TC of 111.3d at
7.8 Kts bound for Masabb Dumyat(31d 30.1.N  31d 50.0'E).

It is 19-42-00 ZT. We decide on a set of 3 bodies for a FIX During
Evening Nautical Twilght.

     Body           Time           Hs             Zn

     Sirus          19-42-56       11d 46.2'      239.1d
     Alioth         19-48-27       61d 55.8'      035.8d
     Spica          19-54-40       31d 59.7'      137.5d

1)  What is our FIX position using Spica as the plotting time?
    What is the Dist Off?
--  ----------------------------------------------------------

2)  What is the TC and Dist to Masabb Dumyat?
    How many days travel is this at a speed of 8 Kts
    to the nearest 0.1 of a mi?
--  ------------------------------------------------

While sailing at 8 Kts, the wind shifts to 270d @ 15 kts, current
Drift is 0.5 @ Set 330d. 1dW Var and 4dE Dev.

3)  What is our CC and SMG?
--  -----------------------

We are sailing from our FIX position on our TC at 8Kts. At
24-00-00 we discover that there is fresh water in the bilge.
A search finds a trickle of water coming from behind the
starboard water tank. We are left with 40 gal of water.


4)  Using 19-54-40 as a plotting time of our FIX and our
    SMG what is the DR at the time of the water leak?
--  -------------------------------------------------------


5)  How many miles have we traveled since our last position FIX?
--  ------------------------------------------------------------

We have an estimated water consumption of 1.5 gal per man/day
and 40 gal remaining. Crew of 6.

6)  How many days of water do we have left? Can we make it
    to Port Said, another 26 miles beyond our landfall before
    running out of water?
--  ---------------------------------------------------------

Supplies at Port Foud the Yacht Club opposite Port Said are adequate
but must be paid for in U.S. Dollars. There are approxumately 100
ships transiting the Suez Canal daily. Special permits are required
for a lay over of more than 24 Hrs by yachts at Port Foud.

7)  If we elect to continue. What is the daily water ration per
    person to the nearest 0.1 of a gallon that will get us to
    Port Said?
--  --------------------------------------------------------

AT 02-00-00 13/05/96 the Helmsman anounces that the knotmeter has
dropped to indicating only 2 Kts. We rig the Walker Patent Log
off the stern taffrail, set to O.O mi.

8) What is the 02-00-00 DR based on our SMG and TC?
-- ------------------------------------------------

We contemplate our situation, the water is short but not
critical. The log is an excellent replacement for the
Knotmeter.

9)  Do we continue to Port Foud?
    Change course immediately for a closer port?
    Wait for a morning round of sights and decide then?
--  ---------------------------------------------------

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.

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


