Секстан и метод Вилсона. Определение места судна измерениями высоты Солнца в полдень.

For me, traditional navigation is more like a form of historical reenactment, an attempt to leap into freedom without the constant crutches of modern civilization. On the Pacific islands, a self-respecting native can easily light a fire by rubbing two sticks together. Moreover, he can teach any white person how to do it in a few minutes. But if you don't know how to do it and don't have matches, you'll literally be left without a fire. Experience is key here. So, I'll play the role of that native. I'm sure that most captains in pre-satellite times didn't think twice about navigation. They'd get out their sextant, chronometer, almanac, and a piece of paper with the sequence of actions written on it. After completing the last step, they could, with a sense of accomplishment, record the coordinates in the log and put everything back in its place. The training didn't take long either. As Jack London wrote in his book "The Voyage of the Snark," " One afternoon I spent at the helm, steering with one hand and calculating with the other from a table of logarithms. The other two evenings—two hours each—I studied the general theory of navigation, and in particular the process of taking meridional altitudes. Then I took a sextant, adjusted the index, and determined the altitude of the sun. The rest of the calculations were mere child's play." So, today we're operating in precisely this traditional 19th-century style, "by the book," with a minimum of theory and calculations. We have a sextant, a watch, and an almanac. We won't discuss emergency situations today where one, two, or all of these components are missing, although such situations exist. And we won't go into detail about the sextant. There won't be any theory either. If, after completing this practical work, you'd like to delve deeper into these wonders, please contact us, vote with likes and subscriptions, as is now customary, and we'll do it. For now, the goal is to demonstrate the trick. Midday solar altitude measurement is the oldest method of determining coordinates in nautical astronomy, and it is still successfully used today. The idea is to catch the moment of local midday, when the Sun is on the north-south line at its highest daytime point. At this moment, measure its altitude and record the exact time. Altitude determines the latitude of a place, and time determines the longitude. It couldn't be simpler. Let's start with that. I apologize in advance to navigation professionals for any inaccuracies and oversimplifications, as well as to yachtsmen who worship Ghipies and the spirit of his navionix, if my words and actions inadvertently cause them unbearable suffering. So, our navigation algorithm—that same captain's note—for today: 1. We don't know our exact location, but we know it approximately, and we can choose a point with whole-number degrees of latitude and longitude nearby. Let's say that's 43 degrees N. and 132 degrees E. This point is located in Ussuri Bay, a few miles from Vladivostok. 2. Today is December 1, 2020. I need to open the almanac and find the time of the sun's culmination, in other words, the time when the sun passes the meridian, which is the same time it crosses the north-south line at zero longitude. I have everything here: the Russian MAE for 2011, the latest Nautical Almanac. As you can see, the difference in the numbers for this date is small. For midday observations, if absolutely necessary, you can use an almanac from any year. There will be an error—well, maybe ten or twenty miles off—but in the case of a zombie apocalypse, that's not critical. The Greenwich meridian is used everywhere, and the time, accordingly, is the same. Let's also immediately write out the equation of time correction for 12:00 AM and 12:00 PM on this day; it will come in handy later. Time of culmination: 11:49 Time correction: 00:00 - 10:59 12:00 - 10:48 3. Now we need to determine when the Sun will pass the 132° East meridian. Longitude, unlike latitude, can be expressed not only in angular numbers but also in time. The Earth rotates! 15 degrees per hour...