How sailor going from Venice to Athens in the ancient time knew to navigate EXCTALY to the port location?
I can understand general direction by stars or even a compass but to navigate to a very specific location is other problem as I see it.
I did some foot navigation and to get to a specific point of very different then a general direction and you can’t use just general direction. If you miss your journey even in 0.5 degree you will get in totally other coast and not to the port you aimed for.
It will be even a bigger problem on the ocean travels. The Portuguese ships going to South America. How the know to land exactly at the port of Mexico or other places.
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Venice to Athens is pretty easy since they would’ve had the shore in view all the time. They had maps and many landmarks to figure out their position.
For ocean travels, you only need to be accurate enough to hit the correct continent and then continue along the shore to your destination.
In order to get from Venice to Athens it is fairly simple as most of the trip is within visible range of the shore. The places where you are crossing open oceans are not far so you can easily just point in the right direction and sail for a day or two until you hit land. Even if you are a bit off you will recognize the land and then follow the coastline until you get to the right destination. But experienced sailors would know the winds and tides well enough to get pretty accurate.
Crossing the Atlantic is more impressive though. You can no longer rely on dead reconing. At least you need a good compass to know which direction you are going and good measuring and logging techniques to get a very accurate track. But you also need to navigate by the sun and stars. Taking measurements of where these are and how high they are above the horizon at any point in time to calculate where you are. It is much easier to do this if you only need to know how far north or south you are, such as when traveling east or west. Fortunantly most of the trade routes over open ocean is going east or west. So basically if the sun is rising too high in the middle of the day that means you have drifted south towards the equator and you give the helm orders to keep a more northernly course. You do this until you hit land.
Map, sextant, compass, stars, Sun and Moon. Lot of math. I imagine once you see land you can also just follow the coastline until you reach the port.
Ancient sailors had compasses and it’s actually not that difficult to get the latitude (north-south distances) using simple sun sights. Many old maps are fairly accurate north and south, but not east and west since that was hard and couldn’t be done accurately until about the mid 1700s. Also don’t forget that many ancient sailors got shipwrecked. Pacific island mariners used stars, wave patterns, birds, clouds, fish types etc to navigate between small islands. As an old sailor, I can confirm what a great invention GPS is.
Away from land, people got lost a lot. For a long time we knew latitude using the stars, but longitude was a problem until the 18th century when the chronometer was invented.
This is a great book that probably answers your question in more detail:
[https://www.amazon.com/Longitude-Genius-Greatest-Scientific-Problem/dp/080271529X](https://www.amazon.com/Longitude-Genius-Greatest-Scientific-Problem/dp/080271529X)
>Anyone alive in the eighteenth century would have known that “the longitude problem” was the thorniest scientific dilemma of the day-and had been for centuries. Lacking the ability to measure their longitude, sailors throughout the great ages of exploration had been literally lost at sea as soon as they lost sight of land. Thousands of lives and the increasing fortunes of nations hung on a resolution. One man, John Harrison, in complete opposition to the scientific community, dared to imagine a mechanical solution-a clock that would keep precise time at sea, something no clock had ever been able to do on land.
Longitude is the dramatic human story of an epic scientific quest and of Harrison’s forty-year obsession with building his perfect timekeeper, known today as the chronometer. Full of heroism and chicanery, it is also a fascinating brief history of astronomy, navigation, and clockmaking, and opens a new window on our world.
There are two facts you need to know to place yourself on a globe: latitude and longitude. Latitude is much easier to find. For example, medieval Arab sailors exploring the Indian Ocean would use a board of a known width with a hole drilled in the center through which passed a cord of a known length. They would hold a knot at the end of the cord in their teeth and hold the board such that it lined up with the horizon and pulled the string taught. When certain stars sat just visible over the board they knew they were at the correct latitude for their destination. At that point it was a matter of keeping a constant bearing east or west until they reached the shore. That’s not the most effective way to travel but it worked. A reliable way to fix longitude wouldn’t be invented for several hundred years; with out satellites and computers the only way to know your longitude is by having a highly accurate clock on board and comparing observed sunrise or sunset compared to a table of known data for a given location(how early or late the sunrise is where you are compared to what your table says it should be for your home port tells you how far east or west you are). If you are able to fix both coordinates it is then possible to plot and maintain great circle routes which are the shortest possible distances on a sphere
It isn’t easy.
Before gps was a regular thing, crossing Lake Ontario in a sail boat. We were heading for a small boat harbor that was basically invisible until you were right on top of it. The trick was to purposely head just a little off. Enough so when you hit shore you knew you needed to turn left. (port) You weren’t exactly sure how far off you were, but you knew you were close and you knew which way to go along the shore.
how do long distance swimmers navigate?
This route would not have been to difficult – as was pointed out – but in the oceanic sense – While Latitude ( N-S) is workable, Longitude requires knowing the time – since the earth is rotating, a Sextant observation needs to know what time it is….and this is why high precision timepieces became so valuable.
Keep in mind also that you aren’t leaving port like a cannonball leaves the barrel. Even if you’re off course when you leave you are constantly checking and adjusting your course.
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