NavList:
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Silicon Sea: Leg 71
From: Dan Hogan
Date: 2001 May 09, 7:49 AM
From: Dan Hogan
Date: 2001 May 09, 7:49 AM
Chart(s): Plotting Sheets
Sight Reduction and
Dead-Reckoning problem Leg 71 050801 Test your knowledge!
---------------------- ------ ------ --------------------
At 18:27:00ZT @ 29/05/2001 we took a departure position of (13d 25.6'N
61d 30.1'W) as we passed between the Lessor Antilles islands of St, Lucia and
St. Vincent. We are bound for, Mid Ocean Point(MOP1)(12d 30.0'N 70d 00.0'W),
in water of more than 1000 mtrs North of Aruba. This is to avoid unfavorable
currents along the coast.
Dev 1.5dE, Var 12dW. Speed is 8.7 Kts, Current Drift 0.7Kts, Set 270.0d.
TC 263.7d.
1) At the log reading of 89.6Nmi, what is the DR position?
-- -------------------------------------------------------
2) At the DR position what is the celestial phenomena that is starting
at this DR Zone Time(ZT)?
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NOTE: Sextant Index correction is on the arc 1.5d.
We then take the following sights:
Body UT Hs
Fomalhaut 08:50:10 40d 54.7'
Polaris 08:50:55 13d 17.3'
Deneb 08:51:05 56d 56.3'
Mars 08:52:03 25d 35.0'
Venus 08:53:22 28d 13.8'
Vega 08:53:45 45d 55.6'
3) What is the FIX position?
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The navigator has been examining nautical chart INT 400. It shows an area
labeled the Aruba Gap (13d 50.0'N 70d 00.0'W) with a favorable current of
1.15 Kts. He decides to make for this waypoint. Var 12dW, Dev 1dE.
Current Set 275d Drift 0.8 Kts. Speed 9.3 Kts.
4) What is the TC and Dist from our FIX to the Aruba Gap
(13d 50.0'N 70d 00.0'W)
-- ------------------------------------------------------
5) What is the Compass Course(CC)/Course-to-Steer for Aruba Gap?
-- -------------------------------------------------------------
6) What is the time enroute to Aruba Gap?
-- --------------------------------------
7) What is the anticipated Speed Made Good(SMG) to Aruba Gap?
-- ----------------------------------------------------------
NOTE:
Lat & Lo = XXd XX.X', Date=DD/MM/YY, HE 9 Feet, Index correction
-1.5', 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(Dead-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
Dan Hogan - dhhogan@veriomail.com
Dan Hogan
dhhogan@verionmail.com
