'Masts on Horizon!' and Flat-Earth Beliefs

[Sammy-rai]

Background: I have started playing SH3 and SH4 this year and am enjoying it a lot. At the same time, this has stirred up my appetite for WWII submarine literature, which has led me to read classic books such as Bucheim's 'U-Boat War' and 'Silent Running'.

A common occurrence in these submarine warfare accounts has been that of the lookout on the bridge crying out 'Masts on the horizon !' or something similar when a sighting of a distant vessel is made.

Being a land-lubber myself, this gave me pause for thought. And after some reflection and googling, I arrived at the explanation that at great distances, it is the tallest part of a ship which is first visible, due to the curvature of the earth blocking one's view of the lower parts of that ship. OK, sounds reasonable to me.

And it also seems to be the case that this phenomenom has been known for hundreds of years before people wrote about it in U-boat books.

At the same time it seems to me that this phenomenom seems to be a pretty cut-and-dried way of determining whether the earth is spherical or flat.

So it makes me scratch my head in confusion when I read about the growing number of people who believe the earth is flat (Flat-Earthers) and the elaborate experiments they perform to test whether the earth is round or not. Just google flat-earth or search for it on YouTube and you'll see what I mean.

What do you think ?

Is there more to the flat-earth situation than I think, or are flat-earthers suffering from a massive case of tunnel-vision ?

[Catfish]

It is difficult for a human mind to imagine a round earth, also to understand 'gravity', or time. Senses adapted evolutionary to the place you live in or on, you have to work on overcoming what seems right or easy at first 'sight'. If you have the latter as a sense.
Without exterior education any life form will find its immediate surrounding a normal given thing and the basis of perception and thinking.

[Aktungbby]

Originally Posted by Catfish

It is difficult for a human mind to imagine a round earth, also to understand 'gravity', or time.

Speak fer yerself ya swabbie !

 

doesn't offer any rules for how far a ship can "see"; however, the DMG does have some default rules about visibility outdoors. According to these rules, characters can normally see about 2 miles out from ground (or sea) level, and 40 miles out if looking from a vantage point such as a hill or mountain "or are otherwise able to look down on the area around them from a height", though rain or fog can significantly reduce visibility (down to 1 mile in heavy rain, or merely a couple hundred feet in fog).

Applied directly, that would suggest that the crew of a ship in clear weather should be able to see about 2 miles (land, not nautical) to the horizon from the deck or 40 miles to the horizon from the crow's nest atop a mast. These rules don't offer any kind of middle ground between those extremes, and a viewing distance of 40 miles is not realistic for an actual ship, on which the crow's nest will be at best a few tens of meters above sea level - but it is all that the rules have to say about how far characters on a ship might be able to see.

Luckily, the formula for estimating horizon distance based on vantage height is simple and, if you assume the planet you're on has earthlike dimensions, there are online calculators which will do it for you. The world of Oerth from the Greyhawk campaign setting (in which Ghosts of Saltmarsh is set) is almost exactly Earth-sized, according to the 2e sourcebook The Adventure Begins (p.9):

Careful mathematical measurements and magical divinations reveal that the circumference of Oerth is 25,200 miles. Thus, the diameter of Oerth is about 8,021.5 miles...

The actual Earth's circumference is is about 24,900 miles, so the values determined by an Earth-based calculator will be near as makes no difference to Oerth. Popular alternative campaign setting the Forgotten Realms' default planet, (Abeir-)Toril, hasn't been specified with such precision so far as I can find, but the the 2e A Grand Tour of the Realms (p.4) does state it is "Earth-sized", so Earth-based vision measurements should also be valid there.

So, using such a calculator, we can easily figure out some more realistic vision distances for your ships. Using the heights of masts given for sample ships in Ghosts of Saltmarsh Appendix A (and assuming, possibly inaccurately, that the given mast height is measured from sea level rather than the deck), we get the following vision distances:

Galley. One 120ft mast. 13.4 miles to horizon.
Keelboat. One 10ft mast. 3.9 miles to horizon.
Longship. One 20ft mast. 5.5 miles to horizon.
Sailing ship or warship. Three 80ft masts. 11 miles to horizon.
Larger ships with taller masts have an advantage in being able to spot other ships from further away. Of course, larger ships should also be easier to spot from a distance as their masts will be visible at much greater distance than the body of the ship... but observers from the top of a mast on a large ship would be able to see the body of a smaller vessel while only the tip of their mast is over the horizon, so would almost certainly spot the other ship first and could probably skirt it without being noticed.

In any event, ships that are close enough to meaningfully interact with each other would be able to see each other from their decks - barring unusual weather such as extremely heavy fog, in which case the vision range is up to the DM's determination of the weather. Once you know your height of eye you simply plug that into the following formula:

1.17 times the square root of your height of eye = Distance to the horizon in nautical miles

For example, if your height of eye is 9 feet above the surface of the water, the formula would be:

1.17 times the square root of 9 = Distance to the horizon in nautical miles.

1.17 * 3 = 3.51 nautical miles
If you want to calculate the distance at which an object becomes visible, you must know your height of eye and the height of the object. You then do the same calculation for your distance to the horizon and the object’s distance to the horizon and add the distances together. For example:
You have the same height of eye of 9 feet so your distance to the horizon is still 3.51 nautical miles. You’re approaching a port that has a lighthouse that is shown on your chart to have a height of 81 feet. Using the same formula you would find that 1.17 times the square root of 81 (1.17 * 9) = 10.53 nautical miles (the light house can be seen 10.53 nautical miles over the horizon)
By adding the two together: 3.51 + 10.53 = 14.04 nautical miles, you should be able to see the lighthouse when you are 14.04 nautical miles away. SEE....SIMPLE

[Ostfriese]

Is there truly a growing number of them? From my perspective the number of flerfs has constantly gone done over the years, and only the hard core is left and making noise.

There's absolutely nothing to flat earth. None of the flerfs' experiments is proving anything they say, on the contrary, more often than not their experiments prove the earth to be spherical and the globe model to be correct.

What these people usually don't understand is the sheer size of the planet - and how small a single human is compared to that.

There's also the problem that the flerfs are so far down the rabbit hole that they can't go back. Usually they simply cannot and will not accept that they are wrong, so they bend the reality in a way that it fits their beliefs. This goes especially for things they don't understand (of which there are many), and the prime example of this is their denial of gravity.

[Sean C]

Flat-Earthers are either trolls or just really gullible [read stupid]. Either way, there's no sense trying to understand or reason with them. Best to just ignore them and get on with your life.

[mapuc]

The earth is somewhere round in shape more like an orange

Markus

[Buddahaid]

Some of this is grounded in their faith.

[August]

They are real touchy too as my signature will attest!

[Platapus]

Originally Posted by Sammy-rai

What do you think ?

Is there more to the flat-earth situation than I think, or are flat-earthers suffering from a massive case of tunnel-vision ?

Maybe they are not very bright

[Jimbuna]

Originally Posted by Sean C

Flat-Earthers are either trolls or just really gullible [read stupid]. Either way, there's no sense trying to understand or reason with them. Best to just ignore them and get on with your life.

Can't argue with the above.

[Platapus]

However, it should be noted that the Flat Earth Society has members from all around the globe

[Buddahaid]

You can see the curve looking at the power lines running across lake Ponchartrain if you want to see.

[Platapus]

When I was working on the salt flats in Utah, you could also see the curvature of the horizon.

[Bilge_Rat]

it is close, apparently the horizon is only 3 miles away when at sea level,

I found it fascinating while studying sea battles when I was a young lad. For example, HMS Prince of Wales opened fire on Bismarck at 26,000 yds or 13 nautical miles so you are in a situation where only sailors in the top masts can spot part of the opposing ship and shells are literally curving around the earth to hit a ship which is mostly beyond the horizon.

The ancient Greeks had already figured out the earth was round in 500 B.C.

[Jimbuna]

Originally Posted by Bilge_Rat

it is close, apparently the horizon is only 3 miles away when at sea level,

I found it fascinating while studying sea battles when I was a young lad. For example, HMS Prince of Wales opened fire on Bismarck at 26,000 yds or 13 nautical miles so you are in a situation where only sailors in the top masts can spot part of the opposing ship and shells are literally curving around the earth to hit a ship which is mostly beyond the horizon.

The ancient Greeks had already figured out the earth was round in 500 B.C.

Your post got me looking a few things up and I came up with this.

The greatest range at which one ship's guns have successfully hit another vessel is 24 km (15 miles), a feat that occurred twice during the second world war. On 8 June 1940 the German battleship Scharnhorst hit the British aircraft carrier Glorious at that range in the North Atlantic, while a month later on 9 July, during the battle of Calabria the British battleship HMS Warspite hit the Italian flagship Guilio Cesare at a similar distance.
https://www.guinnessworldrecords.com...by-a-ships-gun