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Re: Silicon Sea Leg 69: ANSWERS
From: Michael Wescott
Date: 2001 Apr 10, 13:52 EDT
From: Michael Wescott
Date: 2001 Apr 10, 13:52 EDT
dhhogan@XXX.XXX said: > On 9 Apr 2001, at 11:43, Michael Wescott wrote: > > We continue sailing maintaining the same speed and True Course with an > > overcast sky. Then, with the navigator on deck waiting for an opening > > for a Sun shot, we see a spot of land on the horizon ahead. It is > > 20/05/2000 @XXX.XXX > > > 3) What is the DR position? > > -- ------------------------ > > S = 10.7 C = 288.9 T, > > 20/05/2000 12:13:00 ZT = 20/05/2000 16:13:00 UT > -18/05/2000 22:20:00 UT > ======================== > 1 day 17:53:00 > or 41.88 hrs > > Dist = 41.88 * 10.7 = 448.1 nmi > > D.Lat = 448.1 * cos 288.7 = 145.2 = 2d 25.2' > > DR Lat = 9d 50.5' + 2d 25.2' = 12d 15.7' > dmp = mp(12d 15.7') - mp(9d 50.5') > = 147.0 > D.Lo = 147.0 * tan(288.9) > = -429.4 > = -7d 09.4 > DR Lo = -53d 00.0 - 7d 09.4' > = -60d 09.4 > > DR 12d 15.7'N 60d 09.4'W > > Actually this is too far off to make any sense. > We seem to be well past Barbados. > It is off. If you are calculating use a Traverse Table interpolation > may be accumlating an error. Nope. I used meridional parts (that's the mp() function above). Going back the the published answers: > 1. FIX= 9d 50.0'N 53d 00.2'W > 3. DR= 13d 16.4'W 59d 32.3'W and working backwards, there was a course change to 298 d (TC) after the fix. This makes sense, but it wasn't mentioned in the text of the problem and the other course does bring us conveniently south of Barbados. <PRE> -- Mike Wescott Wescott_Mike@XXX.XXX </PRE>