Answer this if you can ?

RaptorMan · Post by **RaptorMan** » 17 years ago

Here`s a

for ya.
If standing within 100 feet of sea level,what is the distance to the horizon on a clear day

My missus had this conversation the other day with a fella who says its between 12-16 miles

personally I think its much more than that

JimBo · Post by **JimBo** » 17 years ago

12 miles sounds about right. A simple formula for calculating this is

H(orizon) in miles = 1.2 X square root of height of observer in feet

e.g. White cliffs of Dover 350 feet, horizon = 22 miles, which is why you can see France from them

.

fjg1955 · Post by **fjg1955** » 17 years ago

thought it was 21 miles to the horizon

wizard · Post by **wizard** » 17 years ago

RaptorMan wrote:Here`s a for ya.
If standing within 100 feet of sea level,what is the distance to the horizon on a clear day
My missus had this conversation the other day with a fella who says its between 12-16 miles
personally I think its much more than that

According to Wikipedia on Google...- The Horizon from 5ft 7 ins height is 2.89 miles away......From a hill/tower of 100 ft. it's 12.25 miles........Therefore from the White Cliffs of Dover, at 350 ft. the Horizon would be 36.75 miles away !.............It takes a Brummie to sort things out for you !!!!

Miz · Post by **Miz** » 17 years ago

It's simple, really. If you want to know the distance to the horizon you simply have to know your height of eye. That is the distance that your eyes are off the surface of the water. If you're in a jon boat, that would probably be about three feet (if you are sitting like you should be in a jon boat). If you were standing at the water's edge, your height of eye is the distance from your eye to your feet.

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, let's say you are on the water in a friend's sport fishing boat and your height of eye is 9 feet above the surface of the water. The formula to calculate distance to the horizon is:

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.

This is not me being clever, unless you class cutting and pasting being clever!!

Just a note for you youngsters out there, 1 mile = 1760yards and 1 nautical mile = 2000yards..

RaptorMan · Post by **RaptorMan** » 17 years ago

Thanks everyone

I think

If I wasn`t confused before, I am now

Post by **snapdragon** » 17 years ago

within 100 ft of sea level?? so if you're 100ft above sea level but in a valley/ depression surrounded by low hills???????

sorry - one of those days

JimBo · Post by **JimBo** » 17 years ago

theres always one isn't there.

bolero · Post by **bolero** » 17 years ago

170 miles (taking into account the curvature of the earth)

further if you have a torch...

stevepratt48 · Post by **stevepratt48** » 17 years ago

You're forgetting that the Earth is flat! The only reasoin the horizon seems close is that others are also looking at it, and there's only so much to go around! (Have a look at 6am, you'll see so much more - QED.

JimBo · Post by **JimBo** » 17 years ago

curl · Post by **curl** » 17 years ago

IT DEPENDS ON HOW FAR YOUR DOG CAN RUN IN 45 SECONDS. GIVE ME THAT INFO AND I CAN EVEN TELL YOU YOUR OLDEST UNCLES LIFE EXPECTANCY WITHIN 42 SECONDS.

JimBo · Post by **JimBo** » 17 years ago

I haven't got a dog!

curl · Post by **curl** » 17 years ago

Then the outlook is bleak. Do you have a gold fish?

hpyraptor · Post by **hpyraptor** » 17 years ago

I reckon you can see about 5 feet if its painted dayglo orange at 100ft from sea level in the english channel. less in the Firth of Forth!

ps I used to be a commercial diver

Raptor Chapter

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