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Chart(s): Plotting Sheet, Chart INT 504

*NOTE*  Year has been changed to 2002 to provide use of the current
Nautical Almanac.

Sight Reduction and
Dead-Reckoning problem     Leg 84  100202   Test your knowledge!
----------------------     ------  ------   --------------------

At 09:19:12ZT 16/07/2001 we were at our entry point for Hilo Hawaii
(19d 44.0'N  155d 04.0'W).

The plan is for a leisurely cruise north through the Hawaiian islands chain.
A stop at Honolulu to re-supply and refit the boat. With our final
destination
being Hanalei Bay, on the island of Kauai. Hanalei Bay is where we will
jump off for our voyage to San Pedro, CA.

Sitting down with our charts we plot the following passage:

    1. Hilo Departure Point(19d 50.0'N  155d 01.0'W)
    2. Alenuihaha Channel Entrance(20d 15.0'N  155d 45.0'W)
    3. Off Maui(20d 30.0'N  156d 25.0'W)
    4. Pailolo Channel Entrance(20d 59.0'N  156d 55.0'W)
    5. Honolulu(21d 16.0'N  157d 53.0'W)
    6. Kaulakahi Channel(22d 15.0'N  159d 25.0'W)
    7. Hanalei Bay(22d 15.0'N  159d 31.0'W)

We spend 5 days at Hilo(19d 50.0'N  155d 01.0'W) then depart. We get a
departure FIX at 02:27:00Hrs after sunrise on the morning of 21/07/2002.

1)  What is the Zone Time(ZT) of the departure FIX?
--  -----------------------------------------------

2)  What is the total plotted distance to Hanalei Bay?
--  --------------------------------------------------

3)  What is the calculated passage time at 9.3 Kts?
--  -----------------------------------------------

At a DR position of (20d 23.7'N  155d 26.9'W) we try for a Noon Sight.
TC 324d.
    Sun LL Hs  89d 49.5'

(See NOTE below for HE and IC)

4)  What is the difficulty with this LAN?
--  --------------------------------------

From the Noon DR position(20d 23.7'N  155d 26.9'W) we change course toward
the Pailolo Channel Entrance(20d 59.0'N  156d 55.0'W). Near evening Nautical
Twilight(ENT) we take the following sights. Speed 10 Kts

    UT          Body            Hs
    05:30:02    Moon LL         23d 20.5'
    05:34:11    Vega            41d 39.7''
    05:40:00    Altair          21d 57.8'
    05:43:55    Polaris         20d 25.1'
    05:46:20    Regulus         16d 08.0'


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

>All our plotting was to near the center of the channels and bodies of
water. Speed 10Kts, Current set 275d, Drift 0.9 Kts. Var. 11dE, Dev 0.5dW.


6)  What is the Compass Course(CC)/Course-to-Steer for the Pailolo
>   Channel Entrance(20d 59.0'N  156d 55.0'W) from our FIX position?
--  ----------------------------------------------------------------

7)  What is the time enroute to the Pailolo Channel Entrance Point
    (20d 59.0'N  156d 55.0'W) from our FIX position?
--  ------------------------------------------------------------------

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
        Mike Wescott - wescott_mike@emc.com
        Dave Weilacher - daveweilacher@earthlink.net
        Tony Capiello - anthony.cappiello@baesystems.com
        Dan Hogan - dhhogan1@@earthlink.net


Dan Hogan
dhhogan1@earthlink.net

   

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