
Chart(s): Plotting Sheet

Sight Reduction and                Revised
Dead-Reckoning problem     Leg 72  052301   Test your knowledge!
----------------------     ------  ------   --------------------

Our Last position FIX was (13d 00.0'N  61d 30.1'W) at 08:50:10UT on 30/05/2001.
We are bound for a point on chart INT 401 marked as Aruba Gap (13d 50.0'N
70d 00.0'W). Aruba Gap provides a favorable westerly current of 1.5 Knts.

We have had overcast skys and have missed some possiable sights. The winds have
been fluky and we have had to tack several times since our last FIX position.

    Tack 1: CC 333.0d - 04Hrs @ 7.5 Kts - Var 12dW Dev 1dE
    Tack 2: CC 242.0d - 11Hrs @ 8.5 Kts - Var 12dW Dev 1.5dE
    Tack 3: CC 262.0d - 08Hrs @ 5.0 Kts - Var 11dW Dev 1.5dE
    Tack 4: CC 307.0d - 10Hrs @ 9.0 Kts - Var 11dW Dev 1.0dE

1)  What is the DR position at the end of the Tack 4?
--  -------------------------------------------------

2)  What is the DR position local Zone Time(ZT) and Date?
    What is the DR position GMT/UT time and Date?
--  -----------------------------------------------------

3)  From the DR position, what is the TC to Aruba Gap
    (13d 50.0'N  70d 00.0'W)?
--  -------------------------------------------------

Our speed is 8.5 Kts, Var 10dW Dev 1.0dE. Current Drift 0.7 Kts Set 265.0d

4)  What is the Compass Course(CC)/Course-to-Steer for Aruba Gap
    from the DR position?
--  ------------------------------------------------------------

The following morning the navigator see stars through breaks in the
clouds. He takes the following sights. Same data as for Q3 & Q4.

    Body        ZT              Hs

    UNKNOWN     05:39:00        13d 53.6' (Steering Compass Bearing 351.7d)
    Mars        05:39:11        18d 14.5'
    UNKNOWN     05:40:03        54d 58.9' (Steering Compass Bearing 007.3d)
    Vega        05:41:06        40d 10.3'
    Venus       05:43:33        35d 25.8'

5)  What is the FIX position?
--  -------------------------

6)  What are the names of the two unknown bodies?
--  ---------------------------------------------

7)  What is the TC and Distance to the Aruba Gap (13d 50.0'N  70d 00.0'W)
    waypoint from our FIX?
--  ---------------------------------------------------------------------

NOTE:
Lat & Lo = XXd XX.X', Date=DD/MM/YY, HE 9 Feet, Index correction
-2.5', Time hh:mm:ss in UT,unless otherwise stated. Silicon
Sea II is a 34,000 lb(15.40t) displacement sailing vessel, 48' 3"
(14.70m) LOA. 39' (12.00m) LWL; Cutter rigged. Can tack to 45d.
Water Tanks = 220 gal(1000 ltrs). Fuel Tanks = 155 gal(700 ltrs).
Fuel consumption .675 gal/Hr at 8.5 Kts. DR(Ded-Reckoning)=position
by sailings, EP(Estimated Position)=DR+current affect. 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 Navigation List Working Group=-

        Peter Smith     - Smith_Peter@EMC.COM
        John Simmonds   - johnsimmo@dingoblue.net.au
        David Weilacher - daveweilacher@earthlink.net
        Tony Cappiello  - cappiello@kearfott.com
        Frank Norris    - NORRIS_FRANKLIN_H@LILLY.COM
        Sam Chan        - schan@socal.rr.com
        Dan Hogan       - dhhogan@veriomail.com



