Very Limited Navigation

[Digital Wind]

How about adding a bar on the trader tool that tells you your rough Latitude (thats the up and down one) but only during night time when you can see the stars?  It will offer players a rough estimate of where they are as long as they aren't moving East or West.  You could also potentially do the same for Longitude at Sunrise and Sunset where historically sailors match the sun-up/down with a clock set, and find their location based on the time difference with a clock set to Home port time.

tldr:  Up/down location only at night, left/right location only at sunrise/sunset.

Edited June 16, 2017 by Digital Wind

[Prater]

Getting latitude requires visibility of the horizon, which is hard at night.  I'd switch it to daytime.

 

Getting Longitude requires a marine chronometer.  While there are other ways, their accuracy requires extreme precision and the best conditions.

Edited June 16, 2017 by Prater

[Salty Dog.]

I'd go with a once-a-(game)-day position when weather is good.

[Remus]

Sailors do indeed sail by the stars, but it is a misconception to think they used the night sky to find their position.

Some stars and planets have been used since prehistoric times for direction (not position). The pole star shows north; the planets and stars on or near the ecliptic (eg Regulus and Spica) roughly show east and west.

Vikings used the pole star for position (latitude only) but their means were very crude and I doubt they were accurate within a couple of hundred miles.

By the late eighteenth century, measurement methods were reasonably accurate with quadrants and sextants, and stars were used for position finding, but you needed to see the horizon so star sights were taken at dawn or dusk. I doubt they'd have had modern tables, so working out position from a star's right ascension and declination would have been far harder then than it is for the 57 selected stars used today, but if I remember rightly Patrick o'Brien has one of his characters take a sight on Vega and he's pretty good on historical accuracy).

For latitude by far the easiest measurement is the noon sight.

The noon sight is rather unreliable for longitude. Better to combine it with a couple of running fixes on the sun, one in the morning, one in the afternoon, and use dead reckoning between them (you need a chronometer as well), but later navigators with modern tables (and chronometers) often prefer to take star sights at dawn and dusk to get a fix.

You can manage without a chronometer (but not without any timepiece whatsoever) by taking a lunar (at night) between the moon and a star or planet close to the ecliptic, but you need to keep accurate time between when you take the lunar and when you take the sun or star sights - accuracy over a few hours rather than months. It isn't nearly as precise as having an accurate chronometer, but at least you don't have that nagging doubt that perhaps your chronometer - the instrument in which you place all your faith - is wrong...

[Prater]

If things were accurate, then the 1714 Longitude Acts and the race to find a reliable way to determine longitude wouldn't have been necessary, nor would the equipping of very expensive marine chronometers been practical.

https://en.wikipedia.org/wiki/History_of_longitude#Problem_of_longitude

https://en.wikipedia.org/wiki/Scilly_naval_disaster_of_1707#Longitude

Edited June 16, 2017 by Prater

[Konali89]

 

in my opinion the navigation as is  ingame is all we need. 
We can navigate by experience. We can navigate based on the distance sorted using the trader tool. It will tell you what the closest cities are and should give you a fairly good idea where you are located. When going in straight lines from A to B and there is no reason to change course mid-trips, the protractor is really nice.

I like it that you need some kind of skill/ experience. Combine all of the above and it should be really easy already.

[Prater]

Problem is, the Marine Chronometer wasn't widespread until after our time period, and no, you can't track time reliably with one of those, reliably enough to use it in navigation.

If things were so accurate and easy, why was it a problem?  Why were there miscalculations?  Why were there wrecks?

Edited June 16, 2017 by Prater

[Digital Wind]

1 hour ago, Prater said:

Getting latitude requires visibility of the horizon, which is hard at night.  I'd switch it to daytime.

 

Getting Longitude requires a marine chronometer.  While there are other ways, their accuracy requires extreme precision and the best conditions.

Fun fact, the best alternative to using an expensive clock to set to..lets say London time..to find Longititude, was to use a telescope and find the positions of the orbits of the 4 Galilean moons around Jupiter.  The only thing harder than doing this on a rocking ship was doing the math.  You can see why people went with the clocks or "Marine Chronometer"

 

 

[Prater]

The Galilean method was near impossible from a ship.

[Digital Wind]

1 minute ago, Prater said:

The Galilean method was near impossible from a ship.

As I said, yes...but on a 3 week sail in the Carribean, or 3 Month to/from the old world.  sailors had a lot of time on their hands to give it a crack.  Find a spit of land and you're golden though.

[Prater]

It is the movement of the ship that makes it nearly impossible, especially when you really need it.

The calculations for lunar methods improved once the books with precalculations were released, but the accuracy was only about 30 miles or so at best.

[Remus]

5 minutes ago, Prater said:

The Galilean method was near impossible from a ship.

It's not too bad under clear skies. You can see the moons clearly enough with a pair of moderate 7x50 binoculars - and I've done it from onboard ship - but I didn't try watching for eclipses.

Unlike lunars or star sights, there's no maths involved. You aren't measuring angles (that would be difficult) but judging when a moon passes behind or emerges from behind (or in front of) Jupiter and looking it up in a table. There are roughly two eclipses per day, so four opportunites for observation, but if two moons are close together you'd probably not be able to distinguish between them which would reduce your opportunities. Also for about 2 months of the year Jupiter is too close to the sun to see the moons clearly.

You'd still need a timepiece of course, to relate your observation of the eclipse to your sun and star sights.

[Prater]

Hodo, how many times do I have to say that marine chronometers, i.e. non-pendulum watches, were extremely expensive and not widespread.  You can't just use a normal pocket watch and expect to get accurate results.

Edited June 16, 2017 by Prater

[Remus]

5 minutes ago, Prater said:

Hodo, how many times do I have to say that marine chronometers, i.e. non-pendulum watches, were extremely expensive and not widespread.  You can't just use a normal pocket watch and expect to get accurate results.

No, but a pocket watch is good enough for lunars. I agree with your 30 miles, by the way. But with a chronomter you wouldn't get much better than 10, and from what I can tell ships 200 years ago seem divided betrween those with chronometers, those who took lunars and those who used dead reckoning.

I found it particularly curious that Captain Ahab in Moby Dick never tried to measure longitude at all, nor did he use dead reckoning. Melville was only a common sailor in the 1840s so may well not have appreciated the finer points of navigation, but in the passage where he mentions the sextant (Ahab took noon sights for latiutude) he would certainly have mentioned a chronometer if Ahab had one (it would have been paricularly relevent), and since the log line was unused (surely this was from Melville's personal experience) he couldn't have been taking running fixes anyway.

[Prater]

16 minutes ago, Hodo said:

1st rates were extremely expensive and not widespread and  they damned near outnumber the number of 7th rates in game.

?

 

[Prater]

1740s-60s, navigation books don't even mention finding longitude.  Their only mention of longitude is in published longitudes for known land locations and using dead reckoning/math to place your ship in between known locations.

1805, mentions of the marine chronometer, but mentions issues with accuracy, proneness to accidents, and expense.

I also seem to remember reading somewhere that observing eclipses you have to know the general time that the eclipse will occur, otherwise you will miss it.  And if you don't know your exact longitude, you don't know the time it will occur, and so it was recommended to watch for the eclipse up to an hour before you thought it should occur.  After you observe it occur, using the helps (published tables to help with calculations), it could take up to half an hour to calculate your longitude, and several times that without the tables.

 

1 hour ago, Remus said:

 But with a chronomter you wouldn't get much better than 10, and from what I can tell ships 200 years ago seem divided betrween those with chronometers, those who took lunars and those who used dead reckoning.

I've read this too, at least in the early 1800s.  The 1805 book I posted the image from above says the lunars method is more reliable, and the accuracy is within 30ish miles.

Edited June 16, 2017 by Prater

[Remus]

35 minutes ago, Prater said:

1740s-60s, navigation books don't even mention finding longitude.  Their only mention of longitude is in published longitudes for known land locations and using dead reckoning/math to place your ship in between known locations.

1805, mentions of the marine chronometer, but mentions issues with accuracy, proneness to accidents, and expense.

I also seem to remember reading somewhere that observing eclipses you have to know the general time that the eclipse will occur, otherwise you will miss it.  And if you don't know your exact longitude, you don't know the time it will occur, and so it was recommended to watch for the eclipse up to an hour before you thought it should occur.  After you observe it occur, using the helps (published tables to help with calculations), it could take up to half an hour to calculate your longitude, and several times that without the tables.

 

I've read this too, at least in the early 1800s.  The 1805 book I posted the image from above says the lunars method is more reliable.

The 1805 excerpt is a little puzzling in making no distinction between using stars and the sun in taking lunars, which makes me think the author wasn't actually practiced in navigation. The moon moves with respect to the stars only slightly slower than the sun, at about 14.5 degrees an hour which of course is 14.5 minutes of a degree per minute of time. Yet the author seems to recommend using the sun, which he correctly states moves in respect to the moon at 30 secomds of a degree per minute of time - nearly 30 times slower, which means 30 times less accurate. It is also a more complicated calculation, since you need to know the positions of both the moon and the sun (which both move) whereas stars are fixed. The inaccuracy in the lunar distance method (if you use a star) isn't so much the sextant reading but inaccuracies in knowing the position of the moon and the compoind error of having to set your timepiece to the lunar measurement then using this to time your fix.

You are entirely correct about needing to guess the time/longitude and spend a very long time watching for an eclipse. I am pretty sure naval telescopes of the day could see the moons - even on board ship - but judging the time of an eclipse is a different matter and lunars look to me to be far easier, though I've never tried either..

The half hour to calculate your longitude (unless you are using the noon sight and the equation of time - inaccurate but very easy) applies whatever means you use to determine the time. It is quicker with tables (I could do three or four stars in about 15 minutes - on top of the 15 minutes or so it would take for the readings) but I don't think they had modern tables 200 years ago.