NavList:
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Silicon Sea: Leg 60
From: Dan Hogan
Date: 2000 Mar 20, 8:19 AM
From: Dan Hogan
Date: 2000 Mar 20, 8:19 AM
Chart(s): Plotting Sheet any Atlas
Dead-Reckoning problem Leg 60 032000 Test your knowledge!
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NOTE: In order to use the current years Nautical Almanac for all new
problems, the year used will be 2000. IT IS STILL THE SAME VOYAGE.
Our last FIX was on 04/04/1999 at 21:30:00UT @ 24d 21.5'S 42d 55.3'W.
TC 218.8d,Speed 9.5Kts.
We are now headed for a waypoint(22d 55.0'S 43d 12.0'W) at the approach
to Rio de Janerio. The weather is overcast, rain. Visibility 16 miles.
Current Drift 10.3Kts, Set 195d.
1) What is our UT ETA(Estimated Time of Arrival) at the way point?
What is the Zone Time(ZT) of our arrival at the waypoint?
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2) What is the distance from our last FIX(24d 21.5'S 42d 55.3'W) to
the Rio de Janerio waypoint at(22d 55.0'S 43d 12.0'W)?
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3) What is the Compass Course(CC) we are steering?
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4) What is the time of local sunrise at the waypoint
(22d 55.0'S 43d 12.0'W)?
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The wind has been variable and fluky.
At 05:10:00ZT in the dim light of the low overcast we make out a mountain
extending into the overcast off to port and another to starboard. We
determine them to be *Corcovado (22d 34.0'S 43d 09.1'W), 704 meters to
port. *Cabucu (22d 49.6'S 42d 51.1'W), 494 meters to starboard. Var is
21dW.
* Positions estimated
Using our Hockey Puck bearing compass from the bow we get the following
bearings:
Corcovado: 340.8d
Cabucu: 14.2d
5) What is our FIX position from the two bearings?
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6) What was our speed made good between the two FIXES?
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Our cruising guide says there are 16 nautical miles from the customs
anchorage.
7) At what speed must we motor to arrive at 09:00:00ZT from our
Bearing FIX position?
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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 - PSmith@IMPS0014.US.DG.COM
John Simmonds- johnsimmo@bigpond.com
Jim Manzari - manzari@bluewin.ch
Dan Hogan - dhhogan@nav.cnchost.com
Dan Hogan
dhhogan@nav.cnchost.com
