Navigation?

Question

how do you use a sextant to navigate at sea

Answer 1

Have you heard of PLANE trigonometry? That's solving the sides and angles of a triangle inscribed on a flat (plane) surface. A sextant is used in solving a triangle inscribed on the surface of a sphere, the earth (Spherical trigonometry).

First you observe a celestial body with a sextant and note the exact time of the observation. Then you calculate the body's position over the earth and your distance from that spot. Sort of like finding the height of a building if you know your distance from it and the angle from your eye to the roof.

That gives you a line where your ship is. Do that three times and where the lines cross is your location. The lines might not cross exactly, so the center of the triangle they form is where you are. The smaller the triangle, the better the accuracy. That's it in a nutshell.

Of course since the sextant can be used to measure any angle, it can be used to observe objects on land to calculate your position too. For example, measuring the angle height of a lighthouse to get your distance away from it.

Answer 2

the short answer is by calculation of the suns height, the time and the  compas bearing to arrive at your current position

Answer 3

you measure the suns angle at noon to give the ships position in latitude and at sunset a compass bearing on the sun and the angle of a known star or two will give you longitude

Answer 4

You need to be trained, which is why the yobs and deadheads are happy with GPS, no training needed.

Answer 5

It is way to involved to discuss here...  Go to

http://www.clipperlight.com/howusesextan...

Answer 6

My dad would know, he was/is a captain in the merchant navy for 30 yrs but i dont know where he is the old bugger. And yes we all use gps these days, sad in a way