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Re: Silicon Sea Leg 69: ANSWERS
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
<PRE>
--
Mike Wescott
Wescott_Mike@XXX.XXX
</PRE>
```
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