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Silicon Sea: Leg 80
From: Dan Hogan
Date: 2001 Oct 03, 7:17 AM

```Chart(s): Plotting Sheets

Sight Reduction and
Dead-Reckoning problem     Leg 80  100301   Test your knowledge!
----------------------     ------  ------   --------------------

We managed a celestial FIX on 30/06/2001 @ 11:53:00UT of (03d 30.0'
097d 30.0'W). We are bound for Mid Ocean Point 1(MOP1)(03d 00.0'N
110d 00.0'W) where we will turn northwest and head for our Hawaii
landfall point at (19d 30.0'N  154d 45.0'W).

The weather has been overcast for the past several days. Seas lumpy, and
wind variable. On 03/07/2001 at 01:37:00ZT and a distance of 754.0 Nmi on
a TC of 267.7d from our last position FIX at (03d 30.0' 097d 30.0'W)
30/06/2001 @ 11:53:00UT the navigator orders a turn to a TC of 307d.

1)  What is the DR position at the time of the turn?
--  ------------------------------------------------

At 09:27:06ZT that same morning we manage a Sun Lower Limb (Sun LL) sight
of:
Hs

42d 01.5'

TC 307d, Speed 10.4 Kts.

2)  What is the DR position at the time of the Sun sight?
What is the UT/GMT time of the sight?
--  ------------------------------------------------------

At a DR position of (04d 10.1'N  111d 32.5'W) at 12:30:22ZT we manage
another Sun sight.

Hs
Sun LL: 71d 05.6'

3)  What is 12:30:22ZT Sun sight called?
--  ------------------------------------

4)  What is the Running FIX(RFIX) position?
--  ---------------------------------------

5)  What is the True Course(TC) and distance to the Hawaii landfall
point at (19d 30.0'N  154d 45.0'W)?
--  ---------------------------------------------------------------

The sky remains a heavy overcast. Winds are variable and indicate a slow
backing. We maintain at True Course of 289.9d.

At the Running FIX position(RFIX) 03/07/2001 @ 19:30:22UT, Current Drift 0.7
Kts, Set 095d. Var 9dE, Dev 1.5dE. Speed 10.0 Kts.

6)  What is the Compass Course(CC)/Course-to-Steer?
--  -----------------------------------------------

We travel for a distance of 646.6 Nmi on a TC of 289.9D.

7)  What is the Dead Reckoning position at this point?
What is the Zone Time(ZT) and Zone Date(ZD) of the DR
position?
--  -------------------------------------------------------

8)  What is the UT/GMT time and date at the DR 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
John Simmonds   - johnsimmo@dingoblue.net.au
Tony Cappiello  - cappiello@kearfott.com
Frank Norris    - NORRIS_FRANKLIN_H@LILLY.COM
Sam Chan        - schan@socal.rr.com
Mike Wescott    - wescott_mike@EMC.COM
Dan Hogan       - dhhogan@veriomail.com

Dan Hogan WA6PBY
C27 "Gacha"
dhhogan@verimail.com
Nav-L Page: http://www.wa6pby.com
```
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