NavList:
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Silicon Sea: Leg 43
From: Dan Hogan
Date: 1998 Jul 08, 4:46 AM
From: Dan Hogan
Date: 1998 Jul 08, 4:46 AM
Chart(s): Plotting Sheets, Bass.gif NOTICE: Beginning with this problem we will be using, The Atlas of Pilot Charts South Pacific Ocean, First Edition 1981. Sight Reduction and Ded-Reckoning problem Leg 43 070898 Test your knowledge! ---------------------- ------ ------ -------------------- Our last DR Position(39d 24.9'E 145 13.7'E) on 29/07/1998 @ 17:53:00. TC,97.5d. Log reading was 920.5mi. Var. 13dE, Dev 2dW. We have the 755mtr mountain (39d 02.0'S 146d 17.0'E) on Wilsons Promotory within our visible horizon. While storing the sextant, after our last sight, it was dropped. Alignment was checked and adjusted. The index now reads 2 degrees "on the arc" when the horizon is aligned. 1) What is the index correction and sign? -- -------------------------------------- Ahead of us is the waypoint(39d 30.0'S 146d 00.0'E) at which we turn up the East Coast of Australia and head toward Sydney. 2) What should we expect the Log reading to be at the waypoint? What is our Zone Time(ZT) Estimated Time of Arrival(ETA) at the waypoint? -- ----------------------------------------------------------- On logging in at the waypoint distance we alter course to 051d. Var 14dE Dev 1dW. 3) At a Log reading 986.8mi we have a land mass visible off of the port beam. What is this? What is the DR position? -- ------------------------------------------------------------- With the land broad abeam, we examine our chart, zero the Walker Log and set a course for a point at (38d 32.0'S 151d 00.0'E) of off Cape Howe. This will let us clear Gabo Island and the Cape before we can alter course towards Sydney. 4) What is the TC and Dist to this waypoint? What is the compass course we are steering? What is our Date and Estimated Time of Arrival(ETA)? -- ---------------------------------------------------- In the night at 01:00:00 we make out the dark shape of land to port. The Log reads 324.0mi. We alter course to parallel it. But keeping well off shore. The Compass now reads 353d. Var 13dE, Dev 1dW. In the morning of 31/07/1998, Log reading 401.3mi, we manage a quick shot of the Sun through clouds. Body Time Hs Sun LL 09:35:22ZT 24d 45.6' 5) What is the Zn of the Sun? What is the Ho? What is the DR position? -- ------------------------- Later, on the same day, we get another sight of the Sun through clouds. Log reading 454.5mi. Body ZT Hs Sun LL 15:30:00 16d 40.8' 6) What is the Running FIX(RFIX) at the time of the second sight? -- -------------------------------------------------------------- Our next landmark that we need to clear is Jervis Bay. We use a waypoint at (35d 10.0'S 151d 00.0'E). Var 14dE, Dev 1dW. Current by Pilot Chart is 11Kts/day set 190. 7) What is the TC and Dist to this point at(35d 10.0'S 151d 00.0'E) from the RFIX? -- ---------------------------------------------------------------- 8) What is the Compass Course Course to steer? -- ------------------------------------------- Note: Lat & Lo = XXd XX.X', Date=DD/MM/YY, HE 8 Feet, Index correction ??', Time hh:mm:ss in UTC/GMT. Silicon Sea is a medium displacement sailing vessel, 40 Feet LOA. 38 Feet LWL; Cutter rigged. Looks a lot like a Mason. Can tack to 45d. Dist to Horizon: Nmi = SQRT HE@mtrs x 2.07; Nmi = SQRT HE@ft x 1.17. Water Tank = 60 gal(Imp.). Fuel Tanks = 90 gal (Imp.). Fuel consumption .450 gal/Hr at 8.3 Kts. 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 - psmith@wellspring.us.dg.com Ron Legere - ronald.legere@yale.edu(temp. Inactive) Tony Severdia- anthonys@pacbell.net Wes Murfin - wmurfin@onslowonline.net (Cartographer) John Simmonds- mobi@netconnect.com.au Jim Manzari - manzari@bluewin.ch Buck Godwin - bgodwin@newsguy.com (Archive Files) Dan Hogan - dhhogan@lightside.com Dan Hogan dhhogan@concentric.net =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-= =-= TO UNSUBSCRIBE, send this message to majordomo@roninhouse.com: =-= =-= navigation =-= =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-=