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Subject: Re: Leg 55 results
From: Dan Hogan (dhhogan@XXX.XXX)
Date: Mon Jun 21 1999 - 12:11:51 EDT
>Here are partial results from Leg 55:
>
>1. Mar 16 2101Z DR = 47 20 S 122 52 W
OK Lat a tad off on Lon
>2. To 52 30 S 100 00 W, TC = 109, dist = 930 nm
Very Close in TC. nm oof per Lon
>3. Compass course = 82, speed made good (not asked) 10.8
Very close same diff as Q2.
>4. Mar 17 0520Z fix, all over the ocean. My 0520 DR is 47 42 S 121
>20 W. I reduced all 5 sights, and the LOPs are everywhere! Some of
>the intercepts are more than 2 deg.
Just pick 3 sights that are spread apart as close to 90 degrees as you
can.
>Conditions here are not the best. Since I don't have the 1999
>Almanac, I'm following the instructions for using last year's edition
>(deduct 15.1' from GHA Aries). Also, I don't have an HO 229 for this
>latitude, so I'm using the reduction tables in the Almanac. Between being
>rusty and using unfamiliar procedures, probably have made some blunders.
>
>body time GHA aLon LHA dec Hc Zn
>Betelgeuse 02:50:00 127 58 120 58 7 N 7 24 34 16 351
>Procyon 02:51:10 102 13 121 13 341 N 5 14 34 14 23
>Peacock 02:51:24 270 43 121 43 149 S56 44 17 52 197
>Regulus 02:52:22 65 15 121 15 304 N11 58 12 15 56
>Bellatrix 02:53:11 136 16 121 16 15 N 6 21 34 04 342
If you have WEB access got to the Navigation-L page
(http://nav.cnchost.com) and down load ALMNAC20.ZIP. It is free ware
and will provide sufficient accuracy for Silicon Sea.
>All plotting was done on sheets of typing paper. DR computations by
>E6-B air navigation slide rule. Sight reduction by paper and pencil. By
>the way, keeping up with Silicon Sea with traditional methods is pretty
>time-consuming, which is the main reason I don't always participate. I've
>noticed everyone else seems to use computers.
POSPLOT.EXE is a freeware program to print plotting sheets on 8.5x11
paper. I have used it on Laserjet and Deskjet printers. On the boat I
use the Q.E.D. plotting sheet.
There are several freeware and Shareware Sight Reduction programs
available at the Navigation-L Web site. I use NAVIG94, shareware, for
the Silicon Sea on the computer.
>I may go back to HO 211 for reductions. The thing I like about 211 is
>that you don't have to contrive an "assumed position" which is miles from
>your DR, and different for each sight. You simply use your DR for the AP.
> The computation is more involved than HO 229 or the NAO tables, but you
>get some time back from the simplified plotting. Plus, as soon as you
>compute the intercept you get instant feedback on the agreement between
>the LOP and your DR.
When I first started in navigation I used 211, but I was prone to
making mistakes with it. I used H.O. 208 and reached a point where I
could reduce a FIX within five minutes. The inspection tables (249 &
229) are faster. I currently use a pair of HP 32SII calculators, one
for Mercator Sailing DR and one for Sight Reduction.
Dan Hogan WA6PBY
dhhogan@XXX.XXX
Navigation-L: http://nav.cnchost.com
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