Real Nav

[Fidgety]

Can anyone post a link please to a good tutorial on using star charts and sextant please.
I have read a couple of tutorials so far and they just explained dead reckoning, which is quite obvious really.
I have spent quite a few hours staring at the star charts provided in game and cant quite seem to grasp them. I can recognize star formations, well some of them, but when looking at the chart I cant figure out where on the chart the human eyes are. Its hard to explain but when I view the chart its almost as if I should be looking from the other side of the paper, like its all been inverted in a photo shop program.
My best guess at the sextant is to aim it at horizon then move slider to north star. When doing this, I do get something close but Im not sure im actually aiming at the right star. Aiming north is obvious, but sometimes at night there are multiple stars due north.
Seems strange the game doesnt make the north star brighter than all the others. I remember at school they said the north star was always brighter than the rest.


Edit/Update


I have found this tutorial on the berbsters tutorial list > https://www.subsim.com/radioroom/showthread.php?t=206103


Using this I am at least good to go and learn from it and will be good to take readings during the day. I am looking for a tutorial similar to this explaining how star charts are used. If anyone can help that would be great as I cant find anything. If nothing turns up I have bookmarked a couple of astronomy websites but having a skim read Im well out of my depth on these websites.

[Fidgety]

Never mind, I didnt notice the documentation that came with TWOS. After reading, I think I can figure it out myself.

[Fidgety]

Im just about to start a new career and Im going to see how it goes not using the navigator. I intend to modify the navigators minimun threshold for making a mistake to something really high to make him useless and see how I get on.
I imagine I am going to spend alot of time reading while in the sub.


One question I have is this, How realistic is the find distance to nearest radio beacon option on the radio operators buttons?
Did the captains really have access to this technology or is it unrealistic?
I dont want to use it if they couldnt do this during the war.


A few days ago when returning to Kiel, it was really foggy and I was struggling to find the entrance to the port. After clicking the button for finding the radio beacon I instantly knew which direction to go. If anyone has knowledge on this please let me know. I shall not be using it untill I get confirmation on here.

[XenonSurf]

The navigation error is already contained in your contact report from Captain's Log, no need to make additional settings, it's as difficult as it gets possibly.

[Fidgety]

Yes but maybe my error threshold is going to be higher than the navigators. If I'm making bigger errors than the max of 8km the navigator does, then when I reload into a game and the game auto places a celestial fix then I am getting help above what I want.
I might just give the navigator a minimun time of say 5 years to calculate the position, that way he can keep himself busy and not interfere with my navigating. :)

[XenonSurf]

Yes but maybe my error threshold is going to be higher than the navigators. If I'm making bigger errors than the max of 8km the navigator does, then when I reload into a game and the game auto places a celestial fix then I am getting help above what I want.
I might just give the navigator a minimun time of say 5 years to calculate the position, that way he can keep himself busy and not interfere with my navigating. :)


I don't know these finesses for RN, but if you want harder difficulty, then first take away all promo points from your crew to diminish their competence. You need to edit the savegame files accordingly. AFAIK the only thing a navigator does in RN is to plot your position on the map, and else just don't use him, don't use other crew members except maybe the sonar guy...
Another way is to give the crew very low morale points so they are about to mutiny... They shouldn't follow your orders and it will only be up to you. I don't know if this works though.


Good luck :)

[Fidgety]

I dont think you realize how fasinating it is navigating using the sextant with star charts and sun almanacs. Its given me a completely new subject to learn and made the game feel completely new to me again.
Its not about making the game harder, I want to simulate and learn RN more than just clicking a button on the navigators tab.

[Sean C]

If you'd like to learn more about real celestial navigation, I'd be happy to help.

[XenonSurf]

I dont think you realize how fasinating it is navigating using the sextant with star charts and sun almanacs. Its given me a completely new subject to learn and made the game feel completely new to me again.
Its not about making the game harder, I want to simulate and learn RN more than just clicking a button on the navigators tab.


Sorry, I didn't mean 'harder difficulty' but 'Do-it-Yourself' (which for me is the same btw). Just don't use the crew, I think this is possible. Use the stars, sextant, 4-bearing method etc. There are a lot of special plotting and attacking tools in the UI, learn to use them, there are some good videos around. There are even some special maps included with instructions, hit E and load the special maps (note that you can scroll the list to make everything visible and selectable!)


There are also tons of useful docs inside the TWoS folders, look in the folder 'Other Readme Files and Docs'.

[Fidgety]

If you'd like to learn more about real celestial navigation, I'd be happy to help.

OK I have something thats bugging me and I cant figure it out yet from 3 websites I have been to.


On this tutorial > https://www.subsim.com/radioroom/showthread.php?t=206103



first we need to find Zenith Distance = 90 - 42.54 we convert the 90 degree to 89.60 - 42.54 = 47.06 is the Zenith Distance



From everything I have read so far, the zenith distance is always 90 degrees minus the altitude angle of the celestial object you measure. I cannot figure out why in this tutorial he converts the 90 to 89.60 before subtracting the altitude angle.


Id also love my question answering in previous post about the radio beacon technology if you know anything about that.


One other thing I'd like to know is when you are logging when the sunrise occurs, do you take the time that the sun first peaks above the horizon or do you go from when the sun has fully past the horizon line? I tried logging the time earlier but from the time it first peaked above horizon to being fully visable took roughly 1 hour and that messed me up from not knowing if I should use GMT or local time. I was in +1 time zone so it was just unfortunate. If I was in +4 or +5 I coulod have figured it out.

[vdr1981]

One question I have is this, How realistic is the find distance to nearest radio beacon option on the radio operators buttons?
Did the captains really have access to this technology or is it unrealistic?
I dont want to use it if they couldnt do this during the war.


A few days ago when returning to Kiel, it was really foggy and I was struggling to find the entrance to the port. After clicking the button for finding the radio beacon I instantly knew which direction to go. If anyone has knowledge on this please let me know. I shall not be using it untill I get confirmation on here.

It's quite realistic I'd say because we know that naval vessels uses NDBs for navigation during the WW2. U-Boats also had DF radio equipment so I decided to implement this small and unique feature in TWoS.

https://uboat.net/articles/id/51

To hide hide navigation marks completely, use the appropriate option in OFEV...Note that the first initial mark when you load the game can not be hidden. That's now SH5 rel nav works.

[Fidgety]

To hide hide navigation marks completely, use the appropriate option in OFEV...Note that the first initial mark when you load the game can not be hidden. That's now SH5 rel nav works.

Yeah I already found that option when looking to neuter the nav man, and your right I couldnt stop the initial map marking after a save.




Its such a shame all my super marks and nav marks I place get lost after reloading a save. Put such effort into them and poof, they dissapear. :(

[vdr1981]

Its such a shame all my super marks and nav marks I place get lost after reloading a save. Put such effort into them and poof, they dissapear. :(

Why don't you save them than and load again later?? :hmmm:

[Fidgety]

Why don't you save them than and load again later?? :hmmm:
Is that possible? I havent noticed anyway to do that.

[vdr1981]

Why don't you save them than and load again later?? :hmmm:
Is that possible? I havent noticed anyway to do that.

Of course...Ship Journal function. You'll find save/open journal buttons there...

[Fidgety]

Thanks, I did see that save button before but didnt know it would reload nav marks or super marks on the map

[Fidgety]

oops

[Sean C]

Sorry I didn't respond earlier. I somehow missed your posts. If you're still looking for some answers ...



OK I have something thats bugging me and I cant figure it out yet from 3 websites I have been to.


On this tutorial > https://www.subsim.com/radioroom/showthread.php?t=206103



first we need to find Zenith Distance = 90 - 42.54 we convert the 90 degree to 89.60 - 42.54 = 47.06 is the Zenith Distance



From everything I have read so far, the zenith distance is always 90 degrees minus the altitude angle of the celestial object you measure. I cannot figure out why in this tutorial he converts the 90 to 89.60 before subtracting the altitude angle.


This is just a way of simplifying the calculation. 89°60' is equal to 90°00' (there are 60 minutes in a degree). When subtracting 42°54' from 90°00', you would have to do this anyway - you can't subtract the 54' from 00', so you would borrow 60' from 90°. Another practice that was common during the time celestial navigation was used was to apply a simple correction to a sun sight of +12' for a lower limb sight or -20' for an upper limb sight. This was a "combined correction" including refraction, semi-diameter and dip of the horizon. In reality, these values vary with different conditions (altitude of the sun, height of eye of the observer, etc.), but these simple corrections were considered "close enough" for the average sight.



Id also love my question answering in previous post about the radio beacon technology if you know anything about that.


I do not know enough about that to provide a good answer, sorry.



One other thing I'd like to know is when you are logging when the sunrise occurs, do you take the time that the sun first peaks above the horizon or do you go from when the sun has fully past the horizon line? I tried logging the time earlier but from the time it first peaked above horizon to being fully visable took roughly 1 hour and that messed me up from not knowing if I should use GMT or local time. I was in +1 time zone so it was just unfortunate. If I was in +4 or +5 I coulod have figured it out.


The generally accepted definitions of "sunrise" and "sunset" are when the upper limb (the "top") of the sun meets the horizon. This is the definition that the "official" Nautical Almanac uses. However, it is interesting to note that when you see the sun very near the horizon, it is actually well below it. This is due to the effect of refraction of the atmosphere. The positions of the sun tabulated in the Nautical Almanac are for the apparent center of the body. The average semi-diameter of the sun is 16'. Refraction can be calculated using the following formula:


-0.0167°/tan(H+7.32/(H+4.32))


... where "H" is the altitude of the body. At 0° altitude, we find that the value for refraction equals -0.0167°/tan(0°+7.32/(0°+4.32)) = -0.5645...° or -0°34'. Add the -16' of semi-diameter to this (to account for the difference between the apparent center and the upper limb) and we find that, at the "moment of sunrise/set", the sun is actually 0°50' below the horizon. That's nearly two apparent sun diameters.


The time of sunrise/set for a particular latitude and longitude can be calculated using the formula for a "time sight":


cos(LHA)=(sin(Ho)-sin(Dec.)·sin(Lat.))/(cos(Dec.)·cos(Lat.))


Once the LHA (local hour angle) is determined, it can be corrected for longitude by using the standard 15°/hour "movement" of the sun (in 24 hours the Sun appears to move 360° around the Earth - 360° ÷ 24hr. = 15° per hr.), and for the "equation of time" [EoT] - the difference between the "apparent" and "mean" places of the sun. The EoT is due to the differing speed of the Earth in its orbit around the Sun and varies from about -14 minutes of time to about +16 minutes of time*. These corrections are necessary because clocks generally keep track of "mean zone time" as opposed to "apparent local solar time".


If you would like me to expand on any of these concepts, just ask. I would be more than happy to.


*The EoT varies in a somewhat irregular way due to the [slightly] elliptical orbit of the Earth around the Sun. This is the source of the "analemma" diagram sometimes found on globes and sun dials.

[Fidgety]

Hi thanks for responding and answering my questions. I already figured the first question out myself from reading things on external sites but haven't got round to looking sunrises up yet. thanks you have saved me a lot of time I think.


I will shortly send you a PM if you dont mind taking a peak.