Re: Silicon Sea: Leg 82

Subject: Re: Silicon Sea: Leg 82
From: Bill Allan (bill.allan@XXX.XXX)
Date: Fri Jan 04 2002 - 07:32:57 EST

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-----Original Message-----
From: Bill Allan [mailto:ballan@XXX.XXX]
Sent: Sunday, December 02, 2001 9:45 PM
To: Bill Allan
Subject: Fw: Silicon Sea: Leg 82

> Sight Reduction and
> Dead-Reckoning problem Leg 82 120101 Test your knowledge!
> ---------------------- ------ ------ --------------------
> Our last position FIX was (11d 29.8'N 132d 29.5'W) 11/07/2001 @
03:40:15UT.
> We are bound for a landfall at Hawaii(19d 30.0'N 154d 45.0'W). Var 10.0dE
> Dev 1.0dE; Current Drift 0.7 Kts Set 285d. Speed 9.7 Kts.
>
> 1) What is the Compass Course(CC)/Course-to-Steer for our Hawaiian
> landfall point?

CCTS is 280deg
> -- ---------------------------------------------------------------
>
> 2) Based on the available information, what is the anticipated
> Speed Made Good(SMG) to the Hawaii waypoint?

        SMG =10.2M
> -- -----------------------------------------------------------
>
> The sky has been overcast for days. we have been unable to get a sight.
> Var 10.0dE Dev 1.0dE. Speed 10.4 Kts.
>
> Since the last FIX(11d 29.8'N 132d 29.5'W) 11/07/2001 @ 03:40:15UT,
> navigating only on dead-reckoning having sailed a total of 1170.0 Nmi.
> We take a SUN LL sight:
>
> DATE UT/GMT Hs
>
> 15/07/2001 20:10:35 61d 20.6'
>
> 3) What is the DR position?
        L = 18deg 10'
        LO = 151deg 20.4'
> -- ------------------------
>
> 4) What is the Speed Made Good(SMG) to this DR?
        SMG = 10.4 knots
> What is the Compass Course(CCMG) this DR?
        CCMG = 280deg
> -- ---------------------------------------------------
>
> At 01:44:36UT that same day we take another SUN LL sight. Use your plotted
> True Course(TC) and Speed 10.2 Kts:
>
> Hs 40d 44.1'
>
> 5) What is the Zn bearing of the SUN at the above sight?
        Zn = 282.6deg
> -- -----------------------------------------------------
>
> 6) What is the RFIX position?
> -- -------------------------
>
> 7) From our DR position, what is the Distance Off and True direction of
> the Running FIX?
> -- --------------------------------------------------------------------
>
> 8) What is the TC and Distance to the Hawaii landfall point at
> (19d 30.0'N 154d 45.0'W) from the FIX?:
>
> You should try at least two of the methods.
>
        I calculated from our departure fix, rather than the rfix.

> On a Great Circle? TC = 293.2deg Dist = 1371.8M
> On a Rhumb Line?
> On Mid-Latitude Sailing? TC = 292.5deg Dist = 1353.2M
> On Mercator Sailing? TC = 290.4deg Dist = 1380.1M
> -- -----------------------------------------------------------
>
> 8a) As an aside try calculating from the RFIX to Sydney
> (33d 50.0'S 151d 20.0'E).
> -- ---------------------------------------------------
>
> NOTE:
> Lat & Lo = XXd XX.X', Date=DD/MM/YY, HE 9 Feet, Index correction
> -2.5', Time hh:mm:ss in UT,unless otherwise stated. Silicon
> Sea II is a 34,000 lb(15.40t) displacement sailing vessel, 48' 3"
> (14.70m) LOA. 39' (12.00m) LWL; Cutter rigged. Can tack to 45d.
> Water Tanks = 220 gal(1000 ltrs). Fuel Tanks = 155 gal(700 ltrs).
> Fuel consumption .675 gal/Hr at 8.5 Kts. DR(Dead-Reckoning)=position
> by sailings, EP(Estimated Position)=DR+current affect. Dist to
> Horizon: Nmi = SQRT HE@XXX.XXX
>
> PLEASE respond with your results and thinking on these exercises to
> the NAVIGATION list at large. If you have questions or problems, A
> lot of folks on the list are knowledgeable and willing to help. Any
> questions or doubtful areas will be responded to promptly. Let us
> hear from you soon!
>
> Good Navigating!
>
> -=The Navigation List Working Group=-
>
> Peter Smith - Smith_Peter@XXX.XXX
> John Simmonds - johnsimmo@XXX.XXX
> Tony Cappiello - cappiello@XXX.XXX
> Frank Norris - NORRIS_FRANKLIN_H@XXX.XXX
> Sam Chan - schan@XXX.XXX
> Mike Wescott - wescott_mike@XXX.XXX
> Dan Hogan - dhhogan@XXX.XXX
>
> *****************************ANSWERS LEG 82*******************************
>
> 1) CC= 279.7d
>
> 2) SMG= 10.4 Kts
>
> 3) DR= 18d 17.6'N 151d 17.8'W
>
> 4) SMG= 10.8 Kts
> CCMG= 280.3d
>
> 5) Zn= 282.5d
>
> 6) RFIX= 18d 37.2'N 152d 13.6'W
>
> 7) DistOff= .2 Nmi
> Direction= 187.7d
>
> 8) GC= Init.
> Course= 290.7d
> Dist= 152.5 Nmi
> RhumbLine
> Course= 290.1d
> Dist= 153.3 Nmi
> Mid-Latitude
> Course= 290.3d
> Dist= 152.5 Nmi
> Mercator
> Course= 290.1d
> Dist= 153.4 Nmi
>
>
> Dan Hogan WA6PBY
> C27 "Gacha"
> dhhogan@XXX.XXX
> Nav-L Page: http://www.wa6pby.com

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