Quote:
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Originally Posted by Kumando
Quote:
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Originally Posted by Brag
Sextant readings of the sun can be taken almost any time the sun is showing. Normally you take two shots about 1.5 hours appart to get a running fix. Then, of course, the local noon shot. Star shots are taken during morning and evening twilight as you need to be able to see both stars and the horizon.
Since you only have a few minutes to shoot the stars, the navigator prepares a star forecast, which allows him to preset the sextant based on his DR (dead reckoning positon at the time of the shoot. This way, he can quickly find the star, make a minor adjustement to the micrometer and secord the reading. Usually he will attempt to establish a fix by shooting 7 stars.
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But in other times than noon, sunrise etc wont be so precise right? I use the wind rose in the map for the sextant simulation(ctrl click) my ideia is use this at the times posted above and only do the ctrl click without the rose at the other times wich will not give me a position so accurate like clicking in the rose. What i need to know is if in the other times is also so accurate to take readings from the sun in reality. |
Your sun shots will give you an LOP (line of position, so you estimate your advance for let's say 1.5 hours and move your LOP to that position, take another shot at the sun and this will give you a fix. This should give you a position with an error less than 5 miles. A good star fix, depending of which tables you use, can give you a position within 200 meters