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Re: Exercise #7 LOP's
From: Mike Burkes
Date: 2008 Jun 3, 18:50 -0700
From: Mike Burkes
Date: 2008 Jun 3, 18:50 -0700
Hi folks, my 1923 May 28 running fix solution yielded 14d 53.2N, 145d 05.1E. Mike Burkes On May 31, 11:58�pm, "Greg R."wrote: > First off, thanks for the practice in working sights using East longitude - it had been long enough that I'd forgotten that for that case you subtract AP longitude minutes from 60, then add that to GHA to get an even value of LHA. My first attempts were ending up with really long intercepts and I couldn't figure out why until I ran it through the Navigator software and the light bulb came on (sometimes we forget how "easy' we have it here in the West longitudes with just subtracting to get LHA). �:-) > > So, here's what I get for sight reductions using Nautical Almanac and Pub. 249 (and Navigator agrees with me within a few tenths of decimal points): > > --------------------------- > > 1) PM Sun line > > AP Lat: 15 deg N > > GHA: 276 deg 29.7' > AP Long: 145 deg 30.3' > LHA: 62 deg > > Dec: N 21 deg 41.1 > > Hc: 31 deg 08' > Ho: 31 deg 04.4' > Intercept: 3.6 NM Away > Zn: 286 deg > > --------------------------- > > 2) Early-morning Jupiter sight > > AP Lat: 15 deg N > > GHA: 243 deg 46.5' > AP Long: 145 deg 13.5' > LHA: 29 deg > > Dec: S 21 deg 46.0 > > Hc: 43 deg 31' > Ho: 43 deg 41.4' > Intercept: 10.4 NM Towards > Zn: 219 deg > > --------------------------- > > I'm assuming this is supposed to be worked as a �running fix - and the vessel appears to have moved 27.5 NM on TC 133 deg between fixes (which is right at 11 hours and gives an average speed of 2.5 Kts. - are we just drifting with the current, or was there not much wind that day?). > > With the LOPs plotted out it looked easier to retire LOP #1 to the DR #2 position rather than the other way around (the Jupiter LOP almost paralleled the vessel's course, and I figured a better "cut" would be had that way). > > So if I plotted this right (and it's been a good long while since I plotted fixes manually), I show a position of 14 deg 50' N / 145 deg 09.8' E at 19h 22m 31s on 28 May 2008. Please tell me I'm at least in the ballpark... �;-) > > -- > GregR > > P.S. Navigator's solution is 14 deg 53.4' N / 145 deg 05.1' E, and I'm guessing that's a lot more accurate than my manual plotting work. > > > > ----- Original Message ----- > From: "Anabasis" > To: "NavList" > Sent: Saturday, May 31, 2008 1:59 AM > Subject: [NavList 5224] Exercise #7 LOP's > > LOP�s > > A couple of straight old LOP�s for people to play with. > > 1) PM sunline: At UTC 06h 23m 23s on 29 May 2008, a lower limb > observation of the sun was made. �DR Lat is 14deg 38.0� N and Long is > 145deg 27.6�E. �Height of eye was 106�, IE is 0.0, T/P is 88 F and > 1011mb. �Hs is 31deg 00.6�. > > 2) �At UTC 19h 22m 31s on 28 May 2008, a LOP of Jupiter was shot. �DR > Lat is 14deg 55.9�N, Long 145deg 07.5� E. �Height of eye is 106�, IE > is 0.0, T/P is 84 F and 1010 mb. �Hs is 43deg 52.4�. > > Determine Azimuth and intercept. > > �Please tell us if you are using an assumed position, or are giving > data based off of the DR position. > > Jeremy- Hide quoted text - > > - Show quoted text - --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---