Real Navigation Mod

[don1reed]

The red circle view is what mariners actually see when using a sextant. Do you suppose it's possible that the obs scope be made into a sextant?

and be able to display the actual angle the body is above the horizon with a split image to get both body & horizon into the view finder?

[ichso]

Originally Posted by don1reed

The red circle view is what mariners actually see when using a sextant. Do you suppose it's possible that the obs scope be made into a sextant?

and be able to display the actual angle the body is above the horizon with a split image to get both body & horizon into the view finder?

The scope's scale should be not too hard to edit so that you can make star or sun readings quickly with it.

The thing with the split image I don't know though. What the modders did so far is to put some additional static images into the game, like those tables on the nav map. Or the FavDialsMod uses some certain script functions to print things onto the big (sliding dials) which gets printed onto the 3D models of the dials and gauges.

But maybe it's not possible to puzzle such screen data of the very dynamic exterior view together to get a split image like you mentioned.

[don1reed]

Re split image:

The horizon mirror on a real sextant of the 39-45 vintage was 1/2 clear glass and 1/2 mirror in order to see the horizon and the reflection of the body simultaneously when the index arm & mirror was rotated after capturing the body and bringing it down congruant with the horizon.

The #2 scope aka Attack scope in SH4 has a split image function used to determine distance of the target ship...I just thought some interprizing, gifted, modder might be able to swing it....wishful thinking on my part.

[Kunsa]

this is my first post
OK I think i have finally cracked the shiii problem.
I have written a sun calculator for real nav that is more accurate than the sun tables that are supplied with real nav. I dont know how to upload information to the internet so if someone can give me some info ...would be great.

Now I havent worked out the star problem yet(next project ) but with my calculator you can at least navigate successfully during the day.

it goes like this:

before sun gets up read polaris 41 degrees
read Dubne 69.5 degrees.
-90-41+89=42N
90-69.5-62=41.5N
ok close enough lets use polaris...entering 42 degrees into my suncalc:
1/1/38 SR 7:30 SS 16:36 Declination 22 50 Equation of Time 3.4mins
we can now approximate noon at:
16:36-7:30=9:06 / 2 = 4:33+7:30 = 12:03.(just for reference)

Sunrise actual 7:22
7:30-7:22 = 8minsx60=480seconds / 4secs per arcminute = 120' east of our meridian. time difference on the clocks is 5hrs.
7:22-2:22 = 5hrsx15 = 75 degrees - (120'/60=2degrees) = 73 W

Noon actual = 11:58 suns altitude = 28 degrees.

our latitude by suns reckoning:
90 degrees - altitude + Suns Declination*
looking north add declination
looking south subtract declination
90-28=62-22.5= Lat:39.5 degrees

now for longitude:
GMT=16:58(see notes on GMT below)
Greenwich apparent time = 16:58 - 3mins(EOT)= 16:55 (I rounded it, probably shouldnt for accuracy)
larger number on top

16:55
-11:58 = 4:57 4x60=240+57=297minutes / 4m per degree = 74 15' W

notes for GMT:
the time in the lower right(in the box) is your local time. the time in white that says "local time" below the date, is actually what local time would be if gmt was the time in the box. think about that for a minute. hehe. so for above..box time was 11:58 and white time was 06:58 so GMTime we ADD the time difference.
ok moving on..

Sunset actual 16:36 exactly 5 hrs west = 75 W

Summary:
Sunrise 42N 73W
Noon 39.5N 74W
Sunset 42N 75W
---------------------
average 40.5N 74W

actual lat/lon for new york harbour = 40 42'N, 74 02'W
so as you can see the more readings you take the more accurate you become, but any one of these readings puts you within 1 degree of your true position.(and actually more precise measurements (accurate star readings) and (3mins EOT instead of 3.4) would have put us closer than 1 degree.

I actually use a modified observation scope with degree markings to take sun readings at noon because my scope can elevate to 90 degrees.(that sun is too bright otherwise)

with this calculator you no longer need 12 or more pages of charts and tables. only a pencil and paper.

Kunsa.
Edit:found filefront so will get some files together, upload and paste a link here soon
p.s. I noticed some people didnt like the thickness of the latitude/;longitude lines on the map. I have solved this as my lat/lon lines are on the lowest 3 zooms(2500km and up) only
and seems to work out quite well. will post that mod too.

thinking about creating a navigation course plotter/finder not sure if it will be that useful.
Edit2:Sppppelling

[Kunsa]

Ive just realized why i was off by 1 degree in my previous post.

its because we assumed our latitude position was 42 degrees and used the sunrise/set times for that latitude in actual fact our latitude turned out to be 40.5 north, so if we had used that latitude our calculations would have been correct.

this means that it was a problem with measuring the star, but the sun calculator was exact.

http://hosted.filefront.com/Kunsa/RealNavAdditions.7z

feedback would be great.

[don1reed]

...Well, I've been away from this thread for a bit, but in the time away, I've been looking at other SIMS. One in particular that caught my eye was, Virtual Sailor vs.7.

Here's a pic of the virtual sextant within that simulation. It works 100%, btw.

It has adjustable shades to block the brightness of the sun.
It will zoom. in/out.
It allows the sailor to bring the heavenly body UL or LL to the horizon.
It measures the angle of altitude in both degrees and 4 digit decimal.
It gives the time in GMT Hr:Min:Sec and 4 digit decimal.



This is what we need for SH3 & 4.

With VS7, I am presently aboard a Type XXI in the middle of the Atlantic in early 1945.



Virtual Sailor is located: http://www.hangsim.com/vs/

Cheers,

[ichso]

I will try the demo. I always wanted a sim where you can actually set sails
Too bad it's not for free though.

[Poul]

Originally Posted by ichso

I will try the demo. I always wanted a sim where you can actually set sails
Too bad it's not for free though.

[code]

Hello! It could not be kept. I have the certificate " the captain of a yacht-steering 3 classes. " But last years had no opportunity to go under sails. But had a lot of pleasure with SH3. Very similar on the present float. The present trial for the seaman. Especially when has appeared mod Real Navigation. Many thanks to authors for pleasure. But to find a meridian of a place - on former a problem. In Virtual Sailor sails behave correctly, when a rate "Beidewind" (when the wind goes to sails in front and a little with a side), or "Galfwind" (the wind goes to sails to perpendicularly case of a yacht). (Excuse. I do not know as it sounds in English). Certainly actually with the present sails of work it is much more. On other basic rates in Virtual Sailor ("fordewind" and "Backshtag") the yacht behaves not so. But all equally is very funny.

[don1reed]

Hello Poul!

Yes, I believe I know what you mean. When sailing into the wind, in English it is called, sailing close-hauled. When sailing across the wind, its called "reaching", as in a broad reach, or beam reach.

Good to have you aboard and good luck with your profession.

Cheers,

[ichso]

Originally Posted by don1reed

Hello Poul!

Yes, I believe I know what you mean. When sailing into the wind, in English it is called, sailing close-hauled. When sailing across the wind, its called "reaching", as in a broad reach, or beam reach.

Good to have you aboard and good luck with your profession.

Cheers,

Right. These where the words I knew I've seen them somewhere, must have been Sid Meier's Pirates :hmm:

[Poul]

Originally Posted by don1reed

Hello Poul!

Yes, I believe I know what you mean. When sailing into the wind, in English it is called, sailing close-hauled. When sailing across the wind, its called "reaching", as in a broad reach, or beam reach.

Good to have you aboard and good luck with your profession.

Cheers,

Yes. It that I wished to tell. Thanks. And how in " Virtual Sailor " has got U-Boot-XXI? In my program it is not present.

[ichso]

Look at http://www.virtual-sailor.net/. There many new models for the game, I found something 'The U-Boat' there, but it's a rebuild of a VII.
Some more googleing for "virtual sailor XXI" gave me the offical addon page of this game, there you find it among many other submarines.

@don1reed: Do you own this game ? I saw that it costs only 27$. Just tried out the demo version which ends after a few minutes of playing. Diving around in the mini uboat was fun (cockpit view is nice).

Are there any interesting tasks in the full version ? Or is it just sailing around for fun ?
The FAQ states nothing about this, if I didn't miss anything.

EDIT: Look what I found:
This is a picture I've taken by myself a year ago or something in the vicinity of the Netherlands:
http://cip.uni-trier.de/~schmidt/Afb069.jpg
And THIS I found at the addon page of vs7:
http://www.hangsim.com/vs/images/downshots/botter.jpg
So, tell me, what kind of freakish coincidence is this ? XD

[don1reed]

Ischo, that pic is SOOOO damn neat!

Yep, I bought the sim. But....

I'm afraid to announce that the virtual sextant is not connected to real world navigation. The celestial globe is tilted about one or two degrees, god knows which direction, which causes bodies to have the wrong altitude for date/time...so, you'll be constantly adjusting the angle of elevation and/or GMT.

As a virtual navigation community, we are sooooo tantalizing close to getting it right I can almost taste it!

The celestial canopy in vs7 is very close to real but not near accurate enough to make fixes to attach courses to. It is, however, much more accurate than SH3 or 4.

Again...great pic.

[ichso]

Originally Posted by don1reed

Ischo, that pic is SOOOO damn neat!

Believe it or not, it was taken with my mobile, and that's not even a very special one, some standart, 2 years old Nokia model.

Before I spend any money on this I have to play the demo with some downloaded ships first. I don't see the big point in JUST sailing around
I don't know if there are any special locations to visit or special things to do.

But the pure sailing and navigating sounds a bit like fun, I must say :hmm:
And there are really beautiful models available, too.

For the navigation issue though, I slowly get the feeling that we have to create our own game because all other ones just don't concentrate on that point enough

[don1reed]

Well, that phonecam is a keeper. Nicely done.

For the navigation issue though, I slowly get the feeling that we have to create our own game because all other ones just don't concentrate on that point enough

I agree

However, this morning using vs7, I put myself near Gibraltar on 21.3.2007 04:10:41 GMT (date of vernal equinox this year) took a sight of polaris and by using Height of Eye 14 feet for DIP correction and Index Correction (IC) of 5.9 moa, and also discovered that the GMT clock was/is 0:37:11 fast. After making the corrections I was right on the money!!!!!!! The line of position was lying right across my boat...he he...and just missed hitting me in the head!!!!!

I made sure I used the equinox to eliminate the seasonal tilt of the earth just to see how far or close I could come...the sextant corrections are very real and emulate life to the "T".

Have a great day.