Real Navigation .

[ETsd4]

Which mods do i have to install for the real navigation? Especially what do i have to do to get rid of my u-Boot position on the map?

[Obelix]

Originally Posted by ETsd4

Which mods do i have to install for the real navigation? Especially what do i have to do to get rid of my u-Boot position on the map?

As minimum:
NewUIs_TDC_5_8_0_ByTheDarkWraith
NewUIs_TDC_5_8_0_Real_Navigation

[ETsd4]

Originally Posted by Obelix

As minimum:
NewUIs_TDC_5_8_0_ByTheDarkWraith
NewUIs_TDC_5_8_0_Real_Navigation

Thanks. Have installed the NewUIs_TDC_5_8_0_Real_Navigation and it works.

Another question concerning position-verification during real navigation:
the SH5-map dont show any lighthouse-symbols.
Is there a list of implemented lighthouses in the game maybe with position-data?

[skookum]

I think, more than any other potential feature, charted navigation aids such as lighthouses would boost the realism of maritime navigation beyond anything else available in a publicly available sim / game today. Not even Ship Simulator gives the user the tools needed to adequately simulate marine navigation. Not that this takes away anything from Ship Simulator. But that game's focus is on ship handling in harbor, not trans-oceanic navigation.

In the mean time, in many cases you can still navigate using edges of land. Just pick three visible points of land more than 10-15 degrees apart each other and take some true bearings. The point where the three lines cross is where your fix is. If you get a "cocked hat" (small triangle instead of a perfect point) then plot your position inside.

I'd like to see if there is a way for SH to plot the ship's position within a circle of uncertainty of say 3-5 nm at an interval of something like every 24 hours at noon, or near sunrise and sunset, simulating the results of an astro fix taken by the ship's navigator. Obviously cloudy weather would make this feature seem a little unrealistic. Regardless this would force the skipper to DR his way around the ocean without having to do all the "extra stuff" required to get an astro fix.

I'm the Captain. I don't need to use a sextant. But I do make decisions based on the best position information available.

And don't forget, depth contours can also be useful wayfinding tools. Take a line of bearing and ping your depth. Then look at your chart to determine the most logical place where both coincide. Doesn't work everywhere. But some places have steeper contours than others.

[TheDarkWraith]

Originally Posted by skookum

I'd like to see if there is a way for SH to plot the ship's position within a circle of uncertainty of say 3-5 nm at an interval of something like every 24 hours at noon, or near sunrise and sunset, simulating the results of an astro fix taken by the ship's navigator. Obviously cloudy weather would make this feature seem a little unrealistic. Regardless this would force the skipper to DR his way around the ocean without having to do all the "extra stuff" required to get an astro fix.

I'm the Captain. I don't need to use a sextant. But I do make decisions based on the best position information available.

I included a new command in Automation that has the navigator plot your current position using celestial navigation. If he's unable to do it celestially (sextant) he'll do it via dead-reckoning. If you make an Automation script for this you can do what you're wanting

[raymond6751]

This is great stuff. I was reading a forum discussion about the map scale and ruler inaccuracy.

Does this have any bearing with the Nav mod? I'm going to try it anyway, because you don't want to miss an opportunity for realism!

Thank you Darkwraith.

[Trevally.]

The maps scale is ok. Its the scale marker at bottom left that is out.
The tools only read to the nearest 50m.

[Jaeger]

Originally Posted by skookum

I'd like to see if there is a way for SH to plot the ship's position within a circle of uncertainty of say 3-5 nm at an interval of something like every 24 hours at noon, or near sunrise and sunset, simulating the results of an astro fix taken by the ship's navigator. Obviously cloudy weather would make this feature seem a little unrealistic. Regardless this would force the skipper to DR his way around the ocean without having to do all the "extra stuff" required to get an astro fix.

I'm the Captain. I don't need to use a sextant. But I do make decisions based on the best position information available.

i dont have a clue about real navigation, i am learning atm. one question about the celestial fix: how often a day a navigator can take a fix? is he only capable to take the fix while sunrise or sunset? if so, we need to implement this restriction to the mod. atm, we can take the celestial fix every time, as often as we want... can somebody please clarify this?

[vanjast]

In the 'old days' longitude(east/west) was determined by a chronometer synchronised to Greenwich.
Latitude (north/south) is usually determined by 'shooting' the polar star (northern hemisphere) and other stars for the southern hemisphere.

Once you have both readings you can determine you approx position.

There are other methods such as:

Explicit knowledge of the 52 or so 'navigation stars'
Triangulating 3 star readings.
The suns noon day position.
Sunrise/Set, Moonrise/Set nautical almanacs for the particular time period that you're in.
Almanacs are valid for about 50 years or so, as the star positions change - You know, we're living on a great ball of dust floating around a gazillion other galaxies, that are all moving

http://www.celestialnavigation.net/
http://en.wikipedia.org/wiki/Celestial_navigation
http://www.starpath.com/celestial/celestial_title.htm

[vanjast]

With regard to 'shooting' the stars and sun. You usually set yourself a disciplined timetable, but the weather can play havoc with this, so you must be able to take a reading at the best opportunistic moment - therefore no restrictions on where and when.

As an example:
In SH3 I set out from Kiel and set course to go around Scotland, down the west coast of Ireland. One day out from Scotland the weather closed in, and that was my last reading for about 4 days
I was then navigating on Dead Reckoning - course, speed and time, from my last know plot. I managed to get pass Scotland and was going south on the west coast before I got my next plot, some 4 days later. By dead reckoning I was about 50Nm out, and so corrected my course to go pass some small island.
I passed that island 24 hours later, 1 hour later than eta and about 5nm to far west.

This was my first RealNav attempt and ... I was chuffed
The only thing missing in SH3/4 are currents, tidal and otherwise. It'll be nice to have these.

i don't have SH5 (DRM @#!$!@%) but in SH3/4, Real Nav implied, no sub icons.. anything that gave you subs position away on the map.

[skookum]

Originally Posted by Jaeger

how often a day a navigator can take a fix? is he only capable to take the fix while sunrise or sunset? ... can somebody please clarify this?

I'll clarify for you. Please excuse the long winded explanation. Hopefully by the end of it I will have answered your question adequately.

First we'll look to the Admiralty Manual of Navigation Vol. I to define an important term: position line; "A position line is any line, drawn on the chart, on which the ship's position is known to lie. ... The simplest form of position line is the line of bearing obtained from a terrestrial object of known position."

Position lines can be obtained from various sources, be they bearings to known objects, distances to known objects, or some other accurate source. When two or more position lines cross, the point at which they cross is called a fix. Navigators "fix" the ship's position on the chart by obtaining position lines by various means and plotting them on the chart along with the time the fix was taken. A fix can consist of position lines of any source, so long as they are obtained and plotted accurately. Navigators then "dead reckon" the ship's current or future position by using the ship's speed and course, and the set (estimated or known drift) to plot a line on the chart that represents the ship's course made good, and to calculate a speed made good.

It's important to remember that a fix always represents the ship's position sometime in the past. As soon as the fix is plotted on the chart it is already obsolete. This is because, unless the ship is perfectly stationary, the ship has moved some distance along its course made good in the time between the navigator's observations and when the fix was plotted.

Celestial navigation uses measurements of celestial objects to obtain position lines which can then be used to create a fix. The navigator calculates the altitude and bearing at which an object should appear from a certain assumed geographic position at a certain time. Then, using a sextant, he observes the object's actual altitude at the time noted from the calculations above. He can make the observation first and then do the calculations, but the times used for each calculation must match the times of each observation precisely. The navigator obtains a position line by noting the difference be between the calculated and observed altitudes of the object and then plotting that difference on the chart as a distance in nautical mile along the object's calculated bearing from the ship's assumed position. From this point on the chart the navigator draws a line perpendicular to the line of bearing to the celestial object. This is the position line.

Simple, right?

These calculations must be performed for each line of position obtained. This means that for a Navigator to obtain a fix using only celestial objects he needs to spend about an hour at the chart table (20 minutes per line, three lines for a "cocked hat" [more certain position than just two lines]).
But in the middle of the ocean with no GPS, spending an hour to get a reasonably accurate fix was well worth the time. The down side is that the navigator was generally lucky to get a fix once per day.

You see, to get a three point astro fix, you not only need to be able see at least three celestial objects in the sky at the same time, but you also need to be able to see the horizon too. If it's too light objects like planets and stars are invisible; too dark and the horizon disappears.
Morning and evening twilight is when the navigator gets the best fixes.

There are ways to obtain fixes at other times during the day, most notably midday. I won't go into that in great detail except to say that with an accurate timepiece one can accurately measure the time at which the sun crosses the southern meridian. Almanacs are then used to obtain a longitude.

Hope this answers some questions folks have about astro.

Cheers

[Jaeger]

These calculations must be performed for each line of position obtained. This means that for a Navigator to obtain a fix using only celestial objects he needs to spend about an hour at the chart table (20 minutes per line, three lines for a "cocked hat" [more certain position than just two lines]).
But in the middle of the ocean with no GPS, spending an hour to get a reasonably accurate fix was well worth the time. The down side is that the navigator was generally lucky to get a fix once per day.

You see, to get a three point astro fix, you not only need to be able see at least three celestial objects in the sky at the same time, but you also need to be able to see the horizon too. If it's too light objects like planets and stars are invisible; too dark and the horizon disappears.
Morning and evening twilight is when the navigator gets the best fixes.

There are ways to obtain fixes at other times during the day, most notably midday. I won't go into that in great detail except to say that with an accurate timepiece one can accurately measure the time at which the sun crosses the southern meridian. Almanacs are then used to obtain a longitude.

Hope this answers some questions folks have about astro.

Cheers

a big thanks for this explanation. for the mod, some details should be changed, i think. if the navigator is happy to get one fix per day, it should be the same situation in the game. perhaps, the button "get a celestial fix" is only available 3 times a day? or the conditions for beeing able to press the button must be more restricitve: best weather conditions are needed. perhaps tdw can change this?