Constructing Noah's Ark Part 1 - Engineering

Image by elmada via Flickr

I have been giving the challenge of showing the mathematics and engineering principles behind Noah's Ark to determine if the Biblical account is really tenable.
You can read the blog post that started this at Responding to Atheism vis Twitter Part 1. I'm not going to be presumptious to think I can really cover this in extreme detail because an entire book could be written on it. Instead I plan to present research and work out a few "back-of-the-envelope calculations" to show my points and to state every assumption I make and why. Part 1 of this post will deal with the engineering and science behind the Ark's construction. Part 2 will deal with the historicity of the Flood account in Genesis by comparing and contrasting it with the Sumarian myth. Which one is correct? Here is the initial challenge being made

Jared said...


You have a degree in engineering? Excellent.


How big is the Ark? 300 Cubits long (at least 450 feet), 30 cubits high.
What's it made of? Gopher Wood. Whuh?


Let's assume the ark is 450 feet long and made of wood (and not the perfect cube some versions of the bible said) how is it that Noah could make a boat larger than any wooden ship before or after?


You're an engineer, show me the maths for a 450 foot plus ship made of woods available in the middle-east. This I have to see.


Oh, and Gilgamesh survived the flood? I'm aware of the history, but you're saying that the Sumerians survived the flood as well? Nicely done.

I'm going to use the information given in Genesis 6: 14-16 to discuss the construction of the Ark.

So make yourself an ark of cypress wood; make rooms in it and coat it with pitch inside and out. 15 This is how you are to build it: The ark is to be 450 feet long, 75 feet wide and 45 feet high. Make a roof for it and finish the ark to within 18 inches of the top. Put a door in the side of the ark and make lower, middle and upper decks. [NIV]

Let's take a look at the Jared's comments. I will frame my comments through them. I will agree that according to the NIV translation the Ark was 450 ft (140 meters ), 75 feet wide (23 meters), and 45 feet (13.5 meters) in height. I'm going to assume that the Jared misspoke and he meant "prism" not "cube" for the shape of the Ark. A cube would have made the ark on sea-worthy. According to the dimensions, the Ark was indeed Prism shaped. In my calculations, I will use metric units. I will also assume that "gopher" wood is a cypress. In the Hebrew we really don't know what kind of wood the Ark was made of but for the purposes of calculation we will assume it's cypress. I am also not going to argue about if the story is true only that it could be true because the Ark is plausible.

It took centuries for people build ships even approaching the size of the Ark. The largest ships today are built on the same proportions as the Ark (length, width, height) of 30 X 5 X 3. These proportions are now known to be the optimum proportions for a ship to remain stable on rough seas. It was through trial and error, study and research that this ratio has been found to be true. Even if you wanted to argue that there was no Noah or no flood, you still have to answer the question of why these proportions were given centuries before modern ship builders found it? The answer is in Genesis: God told Noah to use it. These proportions would make the Ark seaworthy in the most extreme sense.

Let's talk about the size of the Ark and try to estimate how much it weighed. The Ark's volume works out to be 1,518,759 cubic feet or 43,470 cubic meters. The ark had 3 levels which I would estimate to be 33,750 square feet (3,220 square meters), yielding a total area of 101,250 square feet (9,660 square meters). I've read that this about the same amount of space contained by 569 standard rail road cars! The Ark was immense, but not so big that it could not have existed, again people have built larger ships. Now let's try to estimate it's weight. I'm going to over-estimate the weight by tracking the volume of the Ark and multiply by the density of cypress wood which happens to be 510 kg/m³. This would mean that a "ballpark" figure for the Ark's mass, without the mass of passengers, food, and supplies, would be 22,169,700 kg or 48,773,340 lbs or 24,386.67 tons. Recall that the Ark was not a boat. It had no rudder, sail, or any means of propulsion. Therefore it was most like box-shaped making the calculations even more easy. I'm going to assume that since the flood covered all the planet and covered the single land mass we now call Pangea, that the water was fresh water and had little salt in comparison to the ocean today. I'm going to assume that because of cloud cover it was a cold 4 degrees celsius so I can use the density of water at 1000kg/m³ The principal of displacement states that a floating body must displace the same amount of water equal to it's mass. IT's this force that balances gravity and keeps a thing a float. Therefore we need to know the depth of water it would take to equal the weight of the Ark.

Stated another way how much volume would it take to get 48,773,340 kg of water? Look at it this way: (the volume of the water displace)*(density of water) = total mass of the ark. Simple Algebra reveals that the volume of the water must be 48,773.340 cubic meters. This means that it would take a depth of at least 15.147 meters to float the Ark.
i don't have enough information to decide where the waterline was because I don't know how much of the Ark floated above the water. But what I have managed to show is that there was plenty enough water to float the Ark given that there was a flood of Biblical proportions. I've also managed to show that the proportions given for the Ark's size is more than plausible given what is known today. The math shows that there was enough water to float the Ark.

A ship, given these proportions is almost impossible to capsize. Scale models have been built and tested in rough seas conditions and the model did not capsize.


Here are some videos I have found that supplement information I presented here