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Subject: FW: Silicon Sea: Leg 79
From: Russell Sher (rsher@XXX.XXX)
Date: Wed Sep 19 2001 - 02:25:58 EDT
Here are some answer attempts - any verifications?? My intercepts for Q3
seemed a bit long for some of the sights.
Chart(s): Plotting Sheets
Sight Reduction and
Dead-Reckoning problem Leg 79 091701 Test your knowledge!
---------------------- ------ ------ --------------------
Our last FIX position was (03d 00.00'N 082d 00.0'W) @ 10:51:11UT @
26/06/2001. We are sailing toward MOP1(03d 00.0'N 110d 00.0'W) where
we will turn and head for Hawaii.
At a Log distance traveled of 710.5 Nmi from the FIX position. TC 270.0d,
Speed 10.0 Kts, we determine that we have entered the Equatorial Counter
Current.
1) What is the DR position on entering the Equatorial Counter Current?
departure = 710.5 nm, since D lat. = 0.
Diff. Long in minutes = 710.5 *cos (3)), so D Long = 11 deg 49.5', so DR
long
= 093 deg 49'W
DR latitude unchanged: so...
DR = 03 deg 00'N, 093 deg 49.5'W.
-- -------------------------------------------------------------------
On the morning of 30/06/2001 we manage the following sights:
Body UT/GMT Hs
Fomalhaut 11:53:00 54d 01.8'
Deneb 11:55:10 30d 03.8'
Altair 11:57:20 27d 35.1'
Saturn 11:59:05 23d 17.4'
Venus 12:04:11 38d 50.8'
2) What is the DR position at the time of the Fomalhaut sight?
-- -----------------------------------------------------------
distance travelled = 10 knots * 97.3 hours = 973.08 nmiles = departure (due
west)
Diff. long in minutes = 973.08 * cos (3)=971.74' from DR 26/06/2001
D Long = 15 deg 50.3', so DR long = 082 deg 00'W + 16 deg 11.7' = 098 deg
11.7' W
DR latitude unchanged:
DR = 03 deg 00'N, 098 deg 09'W.
3) What is the position FIX?
-- -------------------------
using Navigator Light:
Lat: 03°32.2'N
Lon: 097°30.5'W
Intercepts/Az For each LOP as follows:
Fomalhaut: 37.6' Away/Zn = 202 deg
Deneb : 4.6 To / Zn = 322 deg
Altair : 29.2' Away / Zn = 278 deg
Saturn : 50.2' To / Zn = 069 deg
Venus : 51.4' To / Zn = 072 deg
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