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Subject: Re: Leg 83
From: Dan Hogan (dhhogan1@XXX.XXX)
Date: Tue Sep 24 2002 - 09:27:26 EDT
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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