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Subject: Leg 56 Question # 3
From: Millard Kirk (mkirk@XXX.XXX)
Date: Sat Jul 17 1999 - 10:42:28 EDT
Nav List,
When I joined this list I did the problem by graphic methods when possible
and work the DR's by using formulas from my "Calculator Afloat" book, now
out of print. I chose to purchase a Celesticomp V calculator because it is
dedicated to the navigational problems. It works well, but is unforgiving
if you input data in the wrong format.
Now to question # 3 Leg 56:
I may be missing something so feel free to enlighten me. As I look at
question # 3 I feel there is not enough data to work the problem. Buffeted
for two days; we were buffeted for two days, what was our average speed for
those two days? It must have dropped and would have been recorded on an
hourly basis in keeping the log as the rules of DR require. I think there
are six of the rules for log entries for DR. Entries are made (1) A DR
position will be plotted every hour on the hour, (2) A DR position well be
plotted at the time of every course changes, (3) A DR position will be
plotted at every speed changes , etc.
Starting at 11:50:00 UTC on the 20/03/1999 at position 42d 39.8'S 98d
51.5'W, var 30d E dev 3d W and traveling at a speed of 10.3 Kts. we are to
calculate the DR for a time of 18:48:23 ZT @XXX.XXX By my
calculation for the time it is 3 days 13 hrs 58 min 23 sec or 85hr 59min 23
sec. When I calculate the DR from these parameters I get a DR of 55d
38.7'S 88d 04.2' W.
That is the reason I asked in a previous post what did buffet mean, our
speed must have dropped considerable, and would have given us a much lower
average speed for the 895.8 nm miles traveled in those three days, the
distance from our starting point to the DR. To travel the 895.8 nm, by my
calculations the speed would still around 10.3 kts, and that gives me the DR
of 55d 38.7' S 88d 04.2' W.
I could be way off on my thinking, but I can't get to the DR posted by the
answers for question # 3 from the data presented. What am I missing????
Thanks Dan for the problem. The thing I have learned on this list have come
in mighty handily on my adventures. I have been on an adventure and have
not been participating in the problem for a while.
Still...............
Learning the Hard Way!!
Millard Kirk KB8YQO | mailto:mkirk@XXX.XXX
116 Lewis Ave | http://webpages.marshall.edu/~mkirk/
Barboursville, WV | A West Virginia Blue Water Sailor
25504 | Phone: (304) 736-6544
| First United Methodist Church,
Barboursville, WV
| Homepage
http://www.gbgm-umc.org/bfumcwv/
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