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Re: Leg 46
From: Millard Kirk
Date: 1999 Feb 07, 14:10 EST
From: Millard Kirk
Date: 1999 Feb 07, 14:10 EST
The answer of 70 days for problem #2 was arrived by the following method:
The rhumb line each leg was determined.
Planning Routes--Port Jackson to Boston
Port Jackson(Sydney) Departure--33d 50.8'S 151d 18.0'E
Tasman Sea Waypoint 1-----------34d 00.0'S 151d 40.0'E 20.5 nm
Tasman Sea Waypoint 2-----------38d 40.0'S 166d 45.0'E 783.5 nm
Destination N of Stephens Is.---40d 50.0'S 174d 00.0'E 360.0 nm
Wellington Departure Point------41d 30.0'E 175d 20.0'E 72.4 nm
Cape Horn-----------------------56d 04.0'S 67d 15.0' 4692 nm
WPort Stanley, Falkland Is.------51d 40.0'S 57d 40.0'W 430 nm
Mid-Atlantic Waypoint-----------00d 00.0'N 23d 00.0'W 3576.6 nm
Barbados------------------------13d 10.0'N 59d 20.0'W 2314.2 nm
Cape Cod------------------------42d 10.0'N 70d 00.0'W 1827.9 nm
Boston--------------------------42d 20.0'N 70d 46.0'W 35.6 nm
Total 14,112.2 nm
14,112.2 divided by average speed of 8.4 kts yields 1680.0238 hours
that divided by 24 gave 70.000992 hours.
This answer is based on sailing time only and I did the problem as I thought
it was presented. This in my opinion would only be estimate of distance and
time for planning. I would assume the longer legs one might sail the great
circle, but I did not read the problem in that context. On the other hand
the sailing of each leg might be longer due to winds and currents, and
therefore the overall distance may even be longer. I would assume one would
stop at some of these way points. I know if I sailed approximately 4700
miles I would like to get off the boat for a moment for a little rum or
beer. :-)
By the way which is the correct spelling of "rumbline" , "rumb line", or
"rhumb line". My spell checker on my email does not recognize any of them.
My dictionary says "rhumb line". Now I am not being picky. I am a terrible
speller, among other thing.
Thanks for the comments.
-----Original Message-----
From: Kevin Redden [mailto:kredden@XXX.XXX]
Sent: Sunday, February 07, 1999 1:29 PM
To: owner-navigation@XXX.XXX
Cc: Millard Kirk
Subject: RE: [Nml] Leg 46
After seeing the Silicon Sea cruises for the past two years, I finally
decided to start working the problems. I'm planning on trying to do a long,
celestial-only cruise this year, and I need to brush up on my practice.
I was puzzled by Answer #2. The 70 days given would only be correct if you
sailed rumb line courses for the whole trip. The problem is that nobody in
their right mind would do this! The rumb line distance of 14,112.7 nm is
586.9 nm longer then the Great Circle distance of 13,525.8 nm.
By sailing the legs (other then the departure/arrival legs) using Great
Circle courses, the time required is almost 3 days shorter (67.1 days). Of
course, nobody figured in the time spent on sampling the rum and sobering up
again during the obligatory stop in Barbados! :-)
Why was 70 days given as the answer to #2?
Kevin Redden
Westfield, N.J.
-----Original Message-----
From: owner-navigation@XXX.XXX
[mailto:owner-navigation@XXX.XXX] On Behalf Of Millard Kirk
Sent: Saturday, February 06, 1999 7:29 PM
To: Navigation
Subject: [Nml] Leg 46
Answers to Leg 46
1.) Ans. 14,112.7 nm
2.) Ans. 70 days
3.) Ans. 1530 lbs
4.) Ans. 13.75 days
5.) Ans. TC 111.1 d
Dist 1164.1 nm
6.) Ans. TC 117.8d
Dist. 1156.9 nm
7.) Ans. ZT 05:31:39
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