NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Silicon Sea : Leg 69
From: Dan Hogan
Date: 2001 Apr 04, 11:19 AM
From: Dan Hogan
Date: 2001 Apr 04, 11:19 AM
NOTICE:
This leg uses the year 2000 Nautical Almanac. The next Leg will use the
year 2001 Nautical Almanac.
***************************
Chart(s): Plotting Sheet
Dead-Reckoning problem Leg 69 040401 Test your knowledge!
---------------------- ------ ------ --------------------
The last DR position was(10d 27.9'N 52d 26.4'W) on 18/05/2000 @
12:30:01UT.
Our Speed has been 10.7 Kts, TC 288.9d Var 19dW. Dev 1.5dE. Current Set
285d
Drift 0.5Kts.
On that evening we take the following sights:
Body UT Hs
Sirius 22:15:30 28d 16.3'
Spica 22:17:02 42d 20.6'
Avior 22:19:00 15d 55.3'
Bellatrix 22:19:45 13d 26.5
Dubhe 22:20:12 37d 56.1'
1) What is our FIX position?
-- -------------------------
|2) What is the TC and distance to Barbados(13d 10.0'N 59d 20.0'W)?
-- ----------------------------------------------------------------
|We continue sailing maintaining the same speed and True Course with an
overcast
sky. Then, with the navigator on deck waiting for an opening for a Sun
shot, we
see a spot of land on the horizon ahead. It is 20/05/2000 @ 12:13:00ZT.
3) What is the DR position?
-- ------------------------
4) What day of the week is this?
-- -----------------------------
We want to enter Barbados at Bridgetown, on the Southwest side of the
island. We alter course to a Waypoint(12d 56.0'N 59d 30.0'W) that will
clear us of shallows off the South end of the island.
5) What is the TC and Dist to this Waypoint?
-- -----------------------------------------
6) What is our Estimated Time of Arrival(ETA) at the Waypoint in
Zone Time(ZT)?
-- -------------------------------------------------------------
After arriving at our waypoint we plot a TC of 318d to take us in and
clear of Needham Point before entering Carlisle Bay at Bridgetown.
Var 15dW, Dev 1dE, Speed 10.0Kts, Current Set 270d Drift 1.5Kts.
7) What is the Compass Course(CC)/Course-to-Steer?
-- -----------------------------------------------
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
Dan Hogan - dhhogan@veriomail.com
Dan Hogan
dhhogan@verionmail.com
