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Celestial navigation by day
Historically (and nowadays as well) how can you navigate during the daytime using only the Sun as a reference? I've read a bit about the noon shot (finding your long. at noon, UTC difference, 15 degrees\4 min etc) but in one of the movies at youtube a "simulated" cel nav fix was done at sunrise and at sunset. What's this for?:hmmm::hmmm:
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Someone linked a fantastic "Celestial Navigation Simplified" video here somewhere which explained the whole process. It relies on predetermined tables though - basically a list of the position of the sun at given times from given locations.
So you use the sextant to mark the sun's location at a specific time. You then estimate a location near to where you think you are given all the tables and stuff and figure out how far away from that point your assumed position is. This results in a line you could be along. Do it again an hour later (giving the sun time to move quite a bit) and measure it again, resulting in another possible position line. Where the two lines meet is where you are. At night you could simply take another reading from another star, but using the sun alone you need to triangulate via a second sun reading. I guess the sunset and sunrise (and noon) checks are easiest since you're more likely to have knowledge of sunrise/sunset times then you are to have the multiple books of where the sun is at a certain time from the video? |
thanks for the info kylania, I am doing some experiments in SH4. BTW, do you apply Celnav in any SH? If yes what is your method?
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You can forget about the sky being anywhere near good enough in SH4 to do ANY celestial navigation from it. The only celestial navigation that can be done comes from knowing the position of the sub, putting those figures into a planetarium program and then doing the celestial navigation from there. SH4 was never meant to be a night sky simulation and it is not. It has a sky. That sky, especially solar system positions, is not accurate for date and time.
Typically, what is done with the Sun is meridian transit times. You have an accurate chronometer set for GMT. You get the time the sun passes its highest point. That is noon. The difference between GMT and your transit time is your longitude. This is not particularly accurate due to the size of the sun and the interpolation between precisely timed observations necessary to determine transit time. But it will get you in the same zip code. |
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If it does become a mod, well, honestly, there's a few desires I have that outweigh shooting an azimuth in between missing targets with my torpedoes. But to each their own and I'm not one to spray on anyone's celestial parade. :) |
Arlo, I wouldn't mind the ability to do celestial navigation if it were possible in-game. What's being done now is that people have turned off their position indicator in the nav map. Then they feed the game position to a separate planetarium program. Apparently they even have an in-planetarium sextant so you can actually simulate taking a sight. Then, after doing the calculations to obtain longitude and latitude for your sub, you go back into SH4 to plot the position.
Unfortunately, you also give up the ability to track target positions relative to your boat because there is no indicator for your boat's position. You just end up giving away three times more authenticity than you gain. If you're not playing the game as such and just want to learn celestial navigation it's a great practice tool. But in-game our sky isn't good enough to navigate from. I've demonstrated that moon phases and positions are totally wackazoid. You see, I have some of those whiz bang planetarium programs, Maurice Chevalley's Sky Charts (highly recommended and free!) and The Sky for Windows by Software Bisque. |
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We all got dreams and I support all of em ... just mine more. But until I become a modder all I am is a voice in the peanut gallery. Well, I guess even if I manage to mod, I am. ;) |
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Well, I may reconsider. Anything with the word sex-tent in it is worth exploring if there's a co-ed crew (that was bad but then I'm not known for the best puns). :03:
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What I would like to see in a sub sim is semi-manual everything. When the weather is clear you follow your listed waypoints. When it's not so fine there is a chance the boat will get off course, but the chart will still show you on track, until the next clear day and then you find out where you really are, and lay new waypoints. Same with targetting. You get the range and bearing yourself from the periscope, and the target's estimated position is drawn on the map. You do it again, and it's more accurate. The more you do it the better the solution is. Of course, as with navigation, you might still be off. |
Sounds interesting. But then it becomes a matter of what may or may not be a practical investment for those wonderful modders. Can it be done? Can it be done easier than a mod that'll let me play acey-deucey in the crew's mess? I may hafta put up or shut up and learn to mod my ownself. :cool: (But I'd download a 'celestial nav' mod to give it a go if someone else invested their time on one for the sake of the community. As long as it's TMO 2.2 compat.)
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I'm afraid all this stuff is hard coded in the .exe files. Modding those isn't modding, it's illegal hacking, so you have two choices as a modder.
Choice 1 is to turn off the sub position symbol on the nav map and attack map, find the sub position in the game files and feed that to an exterior planetarium file. That's what has been done by the navigation mod people for SH4. In doing so you give up a ton of realistic and useful things......like the ability to attack and sink opponents. This is not a workable scheme to my way of thinking other than as a proof of concept and a navigation trainer. Choice 2 is not to do celestial navigation in SH4. That's been my path. Or you could go to door #3 where the object of the game seems to be walking around your sub asking how the soup is for the ten thousandth time to build morale, while playing a bizarre Frankenstein poorly executed submarine meets horrible parody of the Sims monster. I'll pass on that one too. I could care less if Johan's girlfriend is pregnant with kittens. |
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