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On 22 Sep 2002, at 13:52, Peter Fogg wrote:

>  Q1)          navigator (9ft) to horizon      3.51nm
> Mauna Loa (4169m) to horizon         +133.66 nm
>       navigator to top ML on horizon    137.2 nm
OK
>
> Q2) First calculate TC along rhumb line from (N18d 37'.2  W152d 13'.6)
> to (N19d 30'.0  W155d 36'.0)
>        by MP&MD  285.3d
>            MP           285.3
>        PS (ML)        285.4
>        by plot          285d
>
> Then, by plotting, with fast speed and weak contrary current,  I get CMG
> 286d and SMG 9.3k,
>        thus TC to steer  284d
> combined error     E   -11d
> CC to steer                273d
RIGHT!
>
> Q3) Time Zone at (W150d +/- 7.5d) is West 10 hours, 10 hours behind UT.
OK

>
> Q4) traverse from N18d 37'.2   W152d 13'.6    at 290d  for 140 nm.
>        MP&MD       N19d 25'.3   W154d 32'.5
>         ML              N19d 25'.1   W154d 32'.0
>         plot              N19d 24'      W154d 31'.5
>
>     elapsed time is 140 nm / SMG 9.3k = 15h 03m 14s
OK

>
> Q5) Am a little unsure what is meant to be done here, assume what is
> needed is the CC to steer from
>     calculated DR (N19d 25'.3  W154d 32'.5) to DO point (N19d 30'.0
> W154d 41'.6).
>     First calculate TC along rhumb line   (distance
>           MP&MD 298.6d                           9.8 nm
>             MP       298.5                             9.8
>          PS(ML)   298.7                             9.8
>             plot      299.0d                          12.0 nm - from
> plotted DR)
>
>     Then another vector diagram, this time with current setting to the
> west. TC to steer 300d
>
> combined error     E   -11d
>
> CC to steer                289d
>     elapsed time is 9.8 nm / SMG 10.5k = 00h 56m 00s
Poor structure of question on my part. Desired is the CC to steer for the
DISTANCE OFF(D.O.) of Cape Kumukahi.
>
> Q6) rhumbline calculation for distance from (N19d 30'.0  W154d 41'.6)
> to (N19d44'.0  W155d 04'.0)
>     by MP&MD  25.3 nm
>          MP          25.4
>          PS (ML)  25.3
>              plot     25.8
> There is no information on current for this leg so shall assume speed is
> 10k.
> elapsed time is 25.3nm / 10k = 02h 31m 48s
OK

>
>
> Q7)     For the ETA at Hilo add the time for each leg to   01:44:36 UT
> on 16/07/2001
>
> + 15:03:14
>
> + 00:56:00
>
> + 02:31:48
>
> = 20:15:38 UT on 16/07/2001
>
> = 10:15:38 ZT on 16/07/2001
Hmmm. One of us is off. I'll have to recheck mine.

> Notes:
> MP&MD     Meridional Parts and Meridional Distances
> MP             Meridional Parts
> PS (ML)      Plane Sailing (Middle Latitude)
> As all the distances involved in these rhumb line and traverse
> calculations are fairly short ones in low latitudes there is little
> difference between the different calculations.



Cheers
-Dan-

   

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