Navigation in real life

[xXNightEagleXx]

Well guys thank you. Is there any ship simulation that simulates celestial navigation? XD I would like to give a try.

[CCIP]

One thing that's good to remember, though, is that this wasn't the captain's job - it was the ship navigator (and his assistants) that took the measurements. There are "real navigation mods" for SHIII and iirc SHIV. I've never tried them - what I would personally rather see in SH instead is just a margin of error introduced into navigation. Otherwise for me having to take measurements as captain of the ship is as much a simulation as running around inside the boat hitting things with a wrench to stop leaks

[BigWalleye]

Originally Posted by CCIP

One thing that's good to remember, though, is that this wasn't the captain's job - it was the ship navigator (and his assistants) that took the measurements. There are "real navigation mods" for SHIII and iirc SHIV. I've never tried them - what I would personally rather see in SH instead is just a margin of error introduced into navigation. Otherwise for me having to take measurements as captain of the ship is as much a simulation as running around inside the boat hitting things with a wrench to stop leaks

SH5 has a really good implementation of "real navigation." Own position is not shown on the nav map. At regular intervals and when ordered, the navigator takes a sighting. Of course,the boat must be surfaced amd the weather clear. Then it takes a variable length of time for him to work up his sighting. His accuracy and speed depend on his skill. When he's done, your estimated position is marked on the map. For a faster result, the navigator will do a DR from the last celestial fix. The error of the DR plot increases with time from the cel fix. The Kaleun doesn't actually do anything - except worry about where his boat really is.

This is one of many things I find really good in SH5. Unfortunately, for me it still lacks flavor. Not enough U-52, too much NCC 1701.

[ColonelSandersLite]

Does that include fistfights and seducing greenskinned babes? If so, I'm outta here...

[TorpX]

Originally Posted by Rockin Robbins

One area related to celestial navigation DID influence the Captain and we have no analog in the game. That area is error mitigation.

...

The correct way to plot a course is to purposely steer a bit further to the north or south .......

It makes sense to me.

If we had to do this, we would probably want distinctive lighthouses and landmarks in our game. Generic features wouldn't help us much.

Originally Posted by BigWalleye

SH5 has a really good implementation of "real navigation." Own position is not shown on the nav map. At regular intervals and when ordered, the navigator takes a sighting. Of course,the boat must be surfaced amd the weather clear. Then it takes a variable length of time for him to work up his sighting. His accuracy and speed depend on his skill. When he's done, your estimated position is marked on the map. For a faster result, the navigator will do a DR from the last celestial fix. The error of the DR plot increases with time from the cel fix. The Kaleun doesn't actually do anything - except worry about where his boat really is.

If someone, who had some programming skills wanted to, most of this could be implemented in SH4. I guess we would have to mark the position on the map ourselves, but we could have randomized errors as a function of navigator skill, etc.

Of course, we would then have to plot our own progress, turns and all, even during our approaches. I'm not sure how many would want to do it. I am presuming those interested in this would not be using map-contacts. It wouldn't make much sense to know our enemies' positions more accurately than we know our own.

[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

[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

[razark]

Originally Posted by TorpX

I am presuming those interested in this would not be using map-contacts. It wouldn't make much sense to know our enemies' positions more accurately than we know our own.

But if you assume you have a decent tracking party working the plot, you should have a really good idea of the enemy's positions relative to you, even if you don't know absolutely where you (and the enemy) are on the map.

[Rockin Robbins]

One area related to celestial navigation DID influence the Captain and we have no analog in the game. That area is error mitigation.

If you are especially good with a sextant, and if your clocks are bang on, your error on a small boat or submarine would likely be in the range of 50 miles. So if you're headed to a port do you sail right at it?

No, you don't. Suppose the port is on a north-south coastline and you navigate straight to it. Here comes the land and......what the hay? No port. Okay, hotshot, which way do we turn? Flip a coin. Ask the exec. Spin a bottle. Doesn't matter if you used a modern computer, its answer would conform to Murphy's law--you turn the wrong way.

The correct way to plot a course is to purposely steer a bit further to the north or south than the size your error envelope. If you are within plus or minus 50 miles, then aim 50 miles north. Either you see the port as you approach or you know you must turn south. Error envelopes change with sea conditions, the length of time since the last valid sighting, skill of the navigator.......

[BigWalleye]

Originally Posted by Rockin Robbins

One area related to celestial navigation DID influence the Captain and we have no analog in the game. That area is error mitigation.

If you are especially good with a sextant, and if your clocks are bang on, your error on a small boat or submarine would likely be in the range of 50 miles. So if you're headed to a port do you sail right at it?

No, you don't. Suppose the port is on a north-south coastline and you navigate straight to it. Here comes the land and......what the hay? No port. Okay, hotshot, which way do we turn? Flip a coin. Ask the exec. Spin a bottle. Doesn't matter if you used a modern computer, its answer would conform to Murphy's law--you turn the wrong way.

The correct way to plot a course is to purposely steer a bit further to the north or south than the size your error envelope. If you are within plus or minus 50 miles, then aim 50 miles north. Either you see the port as you approach or you know you must turn south. Error envelopes change with sea conditions, the length of time since the last valid sighting, skill of the navigator.......

That's what you do whenever you are not sure of the exact position of your vessel. Which, pre-GPS, was pretty much any time you were out of sight of land.

[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.