NavList:
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Silicon Sea: Leg 82
From: Dan Hogan
Date: 2001 Dec 02, 2:51 PM
From: Dan Hogan
Date: 2001 Dec 02, 2:51 PM
Chart(s): Plotting Sheets 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? -- --------------------------------------------------------------- 2) Based on the available information, what is the anticipated Speed Made Good(SMG) to the Hawaii waypoint? -- ----------------------------------------------------------- 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? -- ------------------------ 4) What is the Speed Made Good(SMG) to this DR? What is the Compass Course(CCMG) this DR? -- --------------------------------------------------- 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? -- ----------------------------------------------------- 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. On a Great Circle? On a Rhumb Line? On Mid-Latitude Sailing? On Mercator Sailing? -- ----------------------------------------------------------- 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@mtrs x 2.07; Nmi = SQRT HE@ft x 1.17. 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@EMC.COM John Simmonds - johnsimmo@dingoblue.net.au Tony Cappiello - cappiello@kearfott.com Frank Norris - NORRIS_FRANKLIN_H@LILLY.COM Sam Chan - schan@socal.rr.com Mike Wescott - wescott_mike@EMC.COM Dan Hogan - dhhogan@veriomail.com *****************************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@verimail.com Nav-L Page: http://www.wa6pby.com