This is very easy stuff, I know. I was taught this equation a few months ago and after concentrating on other areas I have completely forgot how to finish the equation after pulling the time out of the box on the date. I cannot remember how to correct it. I have read it in bowditch 100 times plus I have the hawsepipe study disk and I still can’t grasp it, I am freaking out. CAN SOMEBODY PLEASE IN THE MOST SIMPLE OF WORDS EXPLAIN TO ME HOW TO FIGURE OUT ZONE TIME OF SUNRISE AND SUNSET!!!, thank you!
Take your longitude and divide by 15 to get your zd, and then use the DLO correction from your central meridian to your longitude.
I always used 0600 and 1800 for a DR position. With that latitude, interpolate your time. Afterwords, divide your longitude by 15 and apply that to your interpolated time (sub east, add west). That time is Greenwich for your sunset/sunrise. Apply your ZD (add east, sub west) to get your local time of sunrise, sunset.
Pretty good information there!
Lonestar said it in less words, but Dr your position to figure where about you’ll be at the above time and use that position to interpolate for lat/Lon. I use a plane sailing to get the 0600/1800 DR position.
[QUOTE=z-drive;137878]Pretty good information there!
Lonestar said it in less words, but Dr your position to figure where about you’ll be at the above time and use that position to interpolate for lat/Lon. I use a plane sailing to get the 0600/1800 DR position.[/QUOTE]
Yeah I generally use a mid-lat sailing or VPOS sheets. Real life? Look at the passage plan (cadet shipping). Real real life, the ECDIS can tell you.
I haven’t read up on sailings too much, but why do they vary so much in the calculated position? Why are there different types of sailings? Why can’t you use a Mercator for all circumstances, or great circle etc.
[QUOTE=Lone_Star;137886]Yeah I generally use a mid-lat sailing or VPOS sheets. Real life? Look at the passage plan (cadet shipping). Real real life, the ecdis can tell you.
I haven’t read up on sailing too much, by why do they vary so much in the calculated position? Why are there different types of sailings? Why can’t you use a Mercator for all circumstances, or great circle etc.[/QUOTE]
It all has to do with the fact that the earth is not a perfect sphere and no matter what kind of calculation you do there could be some error. Mercator sailings adjust by applying a factor of lattitude to the d-lo by a set factor based on the latitude (meridional parts) rather than just using the mid-lat…guess in THEORY it should be more accurate. But who knows. According to Bowditch you can normally expect more error from steering/wind/currents than from the sailings.
Plane sailing assumes the earth is flat, just good for quick estimates.
Real real real life, use Skymate.
[QUOTE=New3M;137894]Real real real life, use Skymate.[/QUOTE]
Tell the cadet to do it and make themselves useful…
Unfortunately we don’t get a lot of cadets. Sigh…
K got it thanks guys