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Subject: REVISED Leg 49--Silicon Sea
From: Dan Hogan (dhhogan@XXX.XXX)
Date: Wed Jul 07 1999 - 12:16:06 EDT
All:
Below is the revised Silicon Sea Leg 49 w/answers. Some verbage was
changed and some deleted. The changes were done in a manner so as to
minimize the amount of alteration done to the problem. Changes are
marked with a "|".
As always thanks for your input.
The archive has been updated.
***************************Cut Here*****************************
Leg 49 rev. 07/07/1999
Chart(s): Plotting Sheets
Dead-Reckoning problem Leg 49 031599 Test your knowledge!
---------------------- ------ ------ --------------------
Our last position FIX was at (35d 00.2'S 156d 59.7'E) at 09:05:22 @
18/02/1999GMT.Speed 8.7Kts, TC 86.8d Var 13dE, Dev 2.0dE. Current Drift
17 mi/day, set 185 according to the Pilot Chart. We continue on course
through the night. The weather is deteriorating and it begins to rain.
At
|19:45:00GMT the wind heads us and we are forced to change our TC to
14.8d
to port to stay close-hauled.
1) What is the DR position at the time of the course change?
-- ---------------------------------------------------------
|2) Taking all factors in consideration, what is the new TC after
the 14.8d compass heading change to port?
-- --------------------------------------------------------------
A storm has come up and we battle Wind and Sea. The boat is bouncing
hard and the
knotmeter is oscillating wildly. We use the distance log on the
knotmeter. The
storm has caused us to sail the following legs:
TC Speed Dist
| 072d 8.7 91.3
| 027d 8.7 52.2
| 122d 7.5 198.1
| 095d 9.5 311.1
3) What is the DR position at the end of the storm?
-- ------------------------------------------------
4) What is the GMT Time and Date of the DR position?
What is the Zone Time(ZT) and Date of the DR position?
-- ------------------------------------------------------
5) What is the TC and distance to our destination at(40d 50.0'S
174d 20.0'E)?
-- ------------------------------------------------------------
A look at our charts shows that we are off of New Zealand's North
Island.
The chart shows that Mt. Egmont(39d 57.0'E 174d 05.0'E), 2518 mtrs
high,
sits on the headland at the bight between North and South Islands and is
our best land mark.
6) At what distance should we be able to see the mountain on the
horizion?
-------------------------------------------------------------
With a speed of 9.7 Kts.
7) About what what Zone Time(ZT) and date should we expect to have
Mt.Egmont on the horizon?
-- ---------------------------------------------------------------
NOTE:
Lat & Lo = XXd XX.X', Date=DD/MM/YY, HE 9 Feet, Index correction
-2.5', Time hh:mm:ss in UTC/GMT,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@XXX.XXX07; 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@XXX.XXX
John Simmonds- mobi@XXX.XXX
Jim Manzari - manzari@XXX.XXX
Dan Hogan - dhhogan@XXX.XXX
*****************************ANSWERS************************************
Leg 49 (031599) rev. 07/07/1999
|1) DR= 34d 55.0'S 158d 52.1'E
|2) TCMgd= 41.8d
3) DR= 35d 52.4'S 170d 48.5'E
4) GMT= 11:50:00 @ 21/02/1999
ZT= 22:50:00 @ 21/02/1999
5) TC= 150.8d
Dist= 341.4 mi
6) dist= 107.3 mi
7) Date= 22/02/1999
Time= 23:06:49
Dan Hogan WA6PBY
dhhogan@XXX.XXX
Navigation-L: http://nav.cnchost.com
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