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Re: Silicon Sea: Leg 79
From: Michael Wescott
Date: 2001 Sep 28, 12:16 PM
From: Michael Wescott
Date: 2001 Sep 28, 12:16 PM
> > TC 270.0d, Speed 10.0 Kts, Current Drift 1.0 Kts, Set 280.0d. Var > 2.0dE, > > Dev 1.5dE. > > > > 4) What is the Compass Course(CC)/Course-to-Steer to MOP1(03d 00.0'N > > 110d 00.0'W) from the FIX position? > > -- ----------------------------------------------------------------- > > From- 3d 28' N 97d 18' W > To: 3d 0' N 110d 00' W > ---------------------------- > dLat = 28' S dLon = 12d 42' W = 762' W > > Taking departure = dLon, and using a rule of thumb that > sin(x degrees) = tan(x degrees) = x/60 for small angles, > our true course is 60*28/762 = 2.2 degrees south of due west. > The current sets us 1.0*sin(7.8d)=.13nm to the left each hour, Nope, currents sets us 1.0*sin(12.2)=.21 nm to the *right*. > during which we travel 11 miles, so we need to adjust course > to the right 60*.13/11 = 0.7 degrees. Adding it all up, To the *left* 60*.21/11 = 1.1 degrees. > CCTS = TC + current + var + dev > CCTS = 270 - 2.2 + 0.7 - 2.0 - 1.5 = 265d CCTS = 270 - 2.2 - 1.1 - 2.0 - 1.5 = 263.2 (very close for all the approximations). -- Mike Wescott Wescott_Mike@EMC.COM