Navigation in real life

[merc4ulfate]

If you know where you are then you start there and given speed and heading you can know where you are going. The sextant should be used. There will always be errors due to current and wind speeds either adding to or subtracting from your speed so you may be pushed off course a tad.

When I was a helmsman we used two tools to navigate the helm. We had a gyrocompass which gave us true N,S,E,W and we had a compass. Depending on where you are on the earth your heading will be adjusted due to flux in the magnetic field.

A course might be give to steer 345 by 352. One would be your gyroscope heading and the other your magnetic compass heading. If the two did not line up then something was amiss in navigation. There is an offset in heading depending on where in the world you are. I remember our Lead navigator was a 1st class petty officer using the sextant at night to check our position. Over him was an LTJG and the XO a LT.

The XO ran us aground. The 1st class petty officer got us where we were going safely.

[Rockin Robbins]

Originally Posted by ColonelSandersLite

You probably wouldn't want to use the map contact data anyways in that case. When you don't know your exact position, it's way better to use a maneuvering board, instead of an absolute cartesian coordinate system.

A very good chunk of the information you would want for this can be found here:
https://archive.org/details/maneuveringboard00unit

That's a perfect analysis. Our nav map should only be for ship navigation. For tactical actions we should have a Dead Reckoning Tracer (DRT) (properly showing only relative positions), Parallel Motion Protractor (PMP), plot should have a bearing and range indicator showing true compass bearing to the target and range automatically provided from stadimeter or radar, various speed plotting devices and dividers (our nomograph kinda takes their place), and most importantly, because these are error mitigating mechanisms we do NOT have access to, the Periscope Radar Plot, the Stadimeter Plot (!!!!), the Radar Plot and the Navigational Sonar Plot. They also had a bearing rate plot and a bearing difference plot that we don't have. As a double-check against the above many plotting teams had a member with a banjo or is-was. If there was a difference between solutions of plot and TDC and/or banjo/is-was and TDC the fact was announced and torpedoes not fired.

It's easy to see that we have a gross generalization of the excellent tools submariners actually used to plot an attack. Check out the whole thing in the 1950 Submarine Torpedo Fire Control Manual. Chapter 5 is the one that describes the plotting crew's jobs.

Your observation that navigational and tactical plots should be separate is only the beginning of what Silent Hunter 4 lacks. Now our nav map and attack map are supposed to show the result of all the above working together as the captain gets the processed information. One misunderstood function of the attack map is that it represents the comparison of TDC solution with nav plot. If they didn't agree real boats didn't shoot. I've seen many posts where people completely misunderstood the attack map or thought it should be entirely eliminated. In fact it is a good representation of what really happened in fire control parties.

What is not simulated is the error that creeps into every observation, every calculation (they used lots of slide rules we don't have too), that accumulates over time and varies in magnitude by collection method, crew experience and sea conditions.

All these things are why I don't complain when the game is wrong about ship lengths or draft or masthead height. Lacking any errors in other aspects of the plot, these mistakes help reintroduce errors into our solutions. Add that to our being deprived of error mitigating elements of the real plotting crews and we end up with a different but at least present set of difficulties that we can't control.

[6SJ7GT]

I log in after a couple of years and see that people are still interested.

celestial nav was a primary means of navigating in WWII. Star sights would often be within a mile, and a good navigator would be within a fraction of a mile. Someone guessed at 50 mile accuracy, a navigator that far off would be keelhauled, There is an old thread where we were working on this.

http://www.subsim.com/radioroom/show...=celestial+nav

I dont know if the program still works with Stellarium, but there is a lot of info and tutorials on how it works.

6sj7gt

[CaptBones]

Having been a Navigator and an XO and a CO starting back when we still relied on celestial navigation as the primary means of getting from Point A to Point Z and everywhere in between, I can vouch for the accuracy needed to keep your job. A 5-mile triangle for three Lines of Position meant you had to go back and start over; 3 miles was good enough (barely) and if you couldn't consistently hit 2 miles you were due for a refresher course in shooting the stars. Yes, we had LORAN and we had one of the first versions of SATNAV (yeah it was called that at the beginning, not NAVSAT, that came along later). But real navigators took pride in doing it the old fashioned way; if for no other reason, that everything else could and often did, fail. BTW, any "Navigator" who couldn't hit a harbor entrance on the nose was sure to lose his job as well...you can start your radar coastal nav plot well out to sea, especially if the coast is mountainous and/or there are offshore islands to get good returns off of.

Back to the OP though, one of the more "realistic" ways of operating your boat in the game is to pay attention to what the Navigator needs in order to get good positions and maintain an accurate track. You have to be surfaced for morning and evening stars and a sun line at Local Apparent Noon...weather and enemy ASW assets willing. Depending on the weather and the season and latitude, morning stars should be taken from 30-60 minutes before sunrise and evening stars from 30-60 minutes after sunset; Local Apparent Noon should be obvious...as long as you know your approximate longitude and your chronometer is in good working order.

[SilentPrey]

Originally Posted by CaptBones

Having been a Navigator and an XO and a CO starting back when we still relied on celestial navigation as the primary means of getting from Point A to Point Z and everywhere in between, I can vouch for the accuracy needed to keep your job. A 5-mile triangle for three Lines of Position meant you had to go back and start over; 3 miles was good enough (barely) and if you couldn't consistently hit 2 miles you were due for a refresher course in shooting the stars. Yes, we had LORAN and we had one of the first versions of SATNAV (yeah it was called that at the beginning, not NAVSAT, that came along later). But real navigators took pride in doing it the old fashioned way; if for no other reason, that everything else could and often did, fail. BTW, any "Navigator" who couldn't hit a harbor entrance on the nose was sure to lose his job as well...you can start your radar coastal nav plot well out to sea, especially if the coast is mountainous and/or there are offshore islands to get good returns off of.

Back to the OP though, one of the more "realistic" ways of operating your boat in the game is to pay attention to what the Navigator needs in order to get good positions and maintain an accurate track. You have to be surfaced for morning and evening stars and a sun line at Local Apparent Noon...weather and enemy ASW assets willing. Depending on the weather and the season and latitude, morning stars should be taken from 30-60 minutes before sunrise and evening stars from 30-60 minutes after sunset; Local Apparent Noon should be obvious...as long as you know your approximate longitude and your chronometer is in good working order.

Thank you! I was hoping someone who knew this process would chime in with the actual expectations of accuracy. I've read that people could get within a couple hundred yards; that 50 mile figure really had me disappointed/wondering.

[Rockin Robbins]

Originally Posted by CaptBones

Having been a Navigator and an XO and a CO starting back when we still relied on celestial navigation as the primary means of getting from Point A to Point Z and everywhere in between, I can vouch for the accuracy needed to keep your job. A 5-mile triangle for three Lines of Position meant you had to go back and start over; 3 miles was good enough (barely) and if you couldn't consistently hit 2 miles you were due for a refresher course in shooting the stars. Yes, we had LORAN and we had one of the first versions of SATNAV (yeah it was called that at the beginning, not NAVSAT, that came along later). But real navigators took pride in doing it the old fashioned way; if for no other reason, that everything else could and often did, fail. BTW, any "Navigator" who couldn't hit a harbor entrance on the nose was sure to lose his job as well...you can start your radar coastal nav plot well out to sea, especially if the coast is mountainous and/or there are offshore islands to get good returns off of.

Back to the OP though, one of the more "realistic" ways of operating your boat in the game is to pay attention to what the Navigator needs in order to get good positions and maintain an accurate track. You have to be surfaced for morning and evening stars and a sun line at Local Apparent Noon...weather and enemy ASW assets willing. Depending on the weather and the season and latitude, morning stars should be taken from 30-60 minutes before sunrise and evening stars from 30-60 minutes after sunset; Local Apparent Noon should be obvious...as long as you know your approximate longitude and your chronometer is in good working order.

Actual expectations of accuracy on a small boat or submarine would have been magnitudes worse than what you quote. A five mile triangle on a ship unsteady as a submarine without enough reserve buoyancy to be stable enough, would be a random event. Plus your slight height over the water, making getting a real horizon just about impossible would add up to accuracy similar to that of a 40' sailboat. Taking observations from a cork is very different from taking observations on a ship or dry land. Sailing ships had the same accuracy problem and put into shore when they wanted an accurate fix. Nowdays even a destroyer is a 500' ship. They are islands compared to submarines and smaller vessels where the same navigational accuracy is just not attainable.

Great point about the role-playing aspect of being on the surface for sights just before sunrise, just after sunset and at local noon. But all attempts to integrate celestial navigation into the Silent Hunter series are frought with problems. They kill gameplay. The stars are nowhere near what they appear because we've forgotten what dark is. When it is dark like the inside of your closet your eyes can't separate the various brightnesses of stars. The dim ones look brighter than you can imagine and I defy you to pick out constellations as prominent as Ursa Major (the Big Dipper) or Orion, much less the lesser known constellations.

If you are an astronomer and go to a truly dark place you'll spend a night just learning what the real sky looks like and to find constellations you thought you knew all your life. And just the utter magnificence of it is totally distracting. Half a dozen galaxies are visible to the naked eye, thirty or more with binoculars. And through it all, over 3,000 naked eye stars, most of which you never saw before.

[merc4ulfate]

"go to a truly dark place you'll spend a night just learning what the real sky looks like"

a moonless, cloudless night at sea is an unbelievably wonderful sight.

People see a tenth or less of the skies when living around cities that you can view while at sea or far from light pollution on land.

[Crannogman]

Yes, I'm sure that the night is dark, and full of terrors (for merchantmen, at least). Having spent significant time with dark skies in both hemispheres, I can assure you that major constellations are still discernable - seeing all of both dippers in their ursine splendor is a treat. Clearly the Ancients were able to make them out. I imagine even CaptBones hisself had successfully picked out the important stuff at sea on some sort of vessel

[CaptBones]

Sorry RR, I navigated a 44' Luders yawl from Annapolis to Bermuda every year for four years and seldom had a problem getting 5-mile or better fixes.

Before the Navy went all "nuc", I also navigated two Guppy (converted WWII Fleet Boat) submarines in the Atlantic and the Pacific and got equally satisfactory results. Except for adverse weather conditions "conventional" submarine stability on the surface was excellent. The first ship I served on after being converted to a Surface Warfare Officer was a WWII design DE, displacing about 1800 tons and she was not as stable a platform as the Guppy boats. We still never had a problem finding and holding the horizon and getting good fixes. The only times I can recall, in nearly 30 years at sea, when there was ever a problem getting a stable horizon was due to poor weather (fog, rain, clouds, heavy seas, etc.). Unless you're in a serious storm, standing on a rolling, pitching deck and steadying yourself with a sextant or a pair of binoculars in your hand is not terribly difficult for an experienced sailor.

I haven't bothered to try any of the attempted "real" (celestial) navigation MODs in either SH3 or SH4. I just operate as if it needed to be done; being sure to be on the surface for an hour or so before sunrise, after sunset and for a few minutes around noon. It can be carefully integrated into a routine schedule for trim dives, surface searching and hydrophone searching. Boring? Well, sure, I guess. The real world of war at sea was once described as interminable boredom punctuated by bursts of panic.

You're very accurate in your observations about the night sky in today's world. I grew up in the Lake Superior highlands and discovered the real night sky (without any "light pollution" from anywhere) when I was around six years old. I still go up there to rediscover it as often as possible.

[Rockin Robbins]

Originally Posted by CaptBones

Sorry RR, I navigated a 44' Luders yawl from Annapolis to Bermuda every year for four years and seldom had a problem getting 5-mile or better fixes.

What kind of equipment do you have compared to what the Navy was using on submarines in WWII? I understand that subs didn't have the same sextants as surface ships. I've never used that quality sextant before, that probably contributes to my outlook. Mine was a lightweight plastic sextant with Mark 1 eyeball magnification, no artificial horizon. Just like shooting a target rifle, the mass of the sextant contributes you your ability to be steady and get a good sighing.

Before the Navy went all "nuc", I also navigated two Guppy (converted WWII Fleet Boat) submarines in the Atlantic and the Pacific and got equally satisfactory results.

Wow! Guppy I, II or III (I understand there were 4 post Guppy II boats)? I've always pined for Guppy II boats in SH4. Doesn't look like it's going to happen.

Except for adverse weather conditions "conventional" submarine stability on the surface was excellent. The first ship I served on after being converted to a Surface Warfare Officer was a WWII design DE, displacing about 1800 tons and she was not as stable a platform as the Guppy boats. We still never had a problem finding and holding the horizon and getting good fixes. The only times I can recall, in nearly 30 years at sea, when there was ever a problem getting a stable horizon was due to poor weather (fog, rain, clouds, heavy seas, etc.). Unless you're in a serious storm, standing on a rolling, pitching deck and steadying yourself with a sextant or a pair of binoculars in your hand is not terribly difficult for an experienced sailor.

There you have it. I recognize a superior seaman when I see one. The important thing you said was that this is a highly refined skill, not within the capability of a large group of people. What they can do is not what we mortals can accomplish. And remember, in WWII there were no calculators but slide rules and they drop many significant figures. Therefore accurate fixes demanded hand calculations with some pretty intricate math. 3D trig ain't for sissies!

You're very accurate in your observations about the night sky in today's world. I grew up in the Lake Superior highlands and discovered the real night sky (without any "light pollution" from anywhere) when I was around six years old. I still go up there to rediscover it as often as possible.

Yes! When I was a kid our family went on vacation in the UP (upper peninsula of Michigan) and I remember the blackness there too, where you can't see your hand inches from your face and if the moon is out it leaves a stark shadow. Looking at the moon is like looking at the sun in the daytime: blinding! I've heard the Milky Way can cast a shadow, but haven't seen convincing evidence that proves it. City dwellers and those in most suburbs haven't ever seen the Milky Way.

[CaptBones]

Hello again RR...

My Luders yawl sailing days were in the mid-60s. We had pretty much the same optical navigation instruments as any WWII USN ship...older (brass...heavy) sextants, most with 3X or 4X magnification, some Leupold Stevens, some Weems and even one or two really wonderful Plath instruments (I think they might have had 6X magnification...much harder to use in lower light conditions). I've never used a plastic, or even an aluminum one, so can't say anything about comparative results.

In the Guppy days (Clamagore [SS 343/Guppy III] and Grampus [SS 523/Guppy II]) we certainly had some more advanced Navigation equipment than the WWII boats, but we still used both "standard" sextants and bubble sextants...no, we didn't have any "periscope" sextants...those are (or were, back then) only used in aircraft. BTW, IIRC there were 9 or 10 Guppy IIIs.

The marine bubble sextants were very handy if you didn't have a good horizon, but you also didn't get the best results...they were very tough to hold steady. I seem to recall that ours were pretty much knock-offs of German WWII instruments used by the Luftwaffe and the Kriegsmarine.

I'm certainly a mere mortal too, but I suppose it was/is something of a highly developed skill...at least as far as taking good sightings. Fortunately, the trig was almost completely avoidable and the work was mostly a "plug and chug" problem using sight reduction worksheets and tables in the Nautical Almanac (H.O. 214 and H.O. 229). What you needed to be good at was keeping a good DR track and advancing your AP for each separate body you were going to shoot and LOP you wanted to plot.

But, I remember many many of my contemporaries and not a few of my seniors, who just couldn't "get it" right. Then again, I also recall that I never met a Chief or First Class Quartermaster (QMC/QM 1) that couldn't get it right every time, as well as quite a few senior Signalmen and some Boatswains Mates that learned those skills too.

Well, have we beat this subject to death yet? Not exactly hi-jacking the thread but probably twisting it around quite a bit.

[Rockin Robbins]

Originally Posted by CaptBones

Hello again RR...

My Luders yawl sailing days were in the mid-60s. We had pretty much the same optical navigation instruments as any WWII USN ship...older (brass...heavy) sextants, most with 3X or 4X magnification, some Leupold Stevens, some Weems and even one or two really wonderful Plath instruments (I think they might have had 6X magnification...much harder to use in lower light conditions). I've never used a plastic, or even an aluminum one, so can't say anything about comparative results.

Those aren't instruments, they are exquisite works of art!

Originally Posted by CaptBones

In the Guppy days (Clamagore [SS 343/Guppy III] and Grampus [SS 523/Guppy II]) we certainly had some more advanced Navigation equipment than the WWII boats, but we still used both "standard" sextants and bubble sextants...no, we didn't have any "periscope" sextants...those are (or were, back then) only used in aircraft. BTW, IIRC there were 9 or 10 Guppy IIIs.

The marine bubble sextants were very handy if you didn't have a good horizon, but you also didn't get the best results...they were very tough to hold steady. I seem to recall that ours were pretty much knock-offs of German WWII instruments used by the Luftwaffe and the Kriegsmarine.

I'm certainly a mere mortal too, but I suppose it was/is something of a highly developed skill...at least as far as taking good sightings. Fortunately, the trig was almost completely avoidable and the work was mostly a "plug and chug" problem using sight reduction worksheets and tables in the Nautical Almanac (H.O. 214 and H.O. 229). What you needed to be good at was keeping a good DR track and advancing your AP for each separate body you were going to shoot and LOP you wanted to plot.

But, I remember many many of my contemporaries and not a few of my seniors, who just couldn't "get it" right. Then again, I also recall that I never met a Chief or First Class Quartermaster (QMC/QM 1) that couldn't get it right every time, as well as quite a few senior Signalmen and some Boatswains Mates that learned those skills too.

Well, have we beat this subject to death yet? Not exactly hi-jacking the thread but probably twisting it around quite a bit.

Absolutely fascinating and although being a sextant jockey is an invaluable and valued skill on board, to landlubbers they aren't considered very much. And so game manufacturers leave their indispensible skills out of the game.

Irrelevant question that bears on the accuracy of the game. What color are clouds at night with a dark environment? Black. The only way you see clouds is stars aren't where they belong and it's just black there.

[gumbeauregard]

The USN has decided celestial Nav is a good skill to possess.

http://www.wral.com/navy-reinstates-...tion/14990244/

[Aktungbby]

gumbeauregard! after a considerable silent run!