14 Make yourself an ark of gopherwood; make rooms in the ark, and cover it inside and outside with pitch.
15 And this is how you shall make it: The length of the ark shall be three hundred cubits, its width fifty cubits, and its height thirty cubits.
16 You shall make a window for the ark, and you shall finish it to a cubit from above; and set the door of the ark in its side. You shall make it with lower, second, and third decks.
17 And behold, I Myself am bringing floodwaters on the earth, to destroy from under heaven all flesh in which is the breath of life; everything that is on the earth shall die.
To be very conservative, assume the cubit to have been only 17.5 inches, the shortest of all the cubits, so far as is known. In that case, the Ark would have been 438 feet long, 72.9 feet wide, and 43.8 feet high. It can be shown hydrodynamically that a gigantic box of such dimensions would be exceedingly stable, almost impossible to capsize. Even in a sea of gigantic waves, the ark could be tilted through any angle up to just short of 90° and would immediately thereafter right itself again. Furthermore, it would tend to align itself parallel with the direction of major wave advance and thus be subject to minimum pitching most of the time.
With the dimensions as calculated, the total volumetric capacity of the Ark was approximately 1,400,000 cubic feet, which is equal to the volumetric capacity of 522 standard livestock cars such as used on modern American railroads. Since it is known that about 240 sheep can be transported in one stock car, a total of over 125,000 sheep could have been carried in the Ark.
A few other details of the Ark’s construction are given. It was to have three stories, each ten cubits high; and each of these “decks” was to be divided into various “rooms” (literally “nests”—thus apparently each of appropriate size for the individual animals to rest in). The Ark was to be made of “gopher wood,” the exact nature of which is unknown today, though apparently some type of dense, hard wood; and it was to be made waterproof and resistant to decay by impregnation with “pitch,” inside and out.
The word for “pitch” (Hebrew kopher) is different from that used in other places in the Old Testament. it is equivalent to the Hebrew kaphar (“to cover”) and, in the noun form, means simply a “covering.” However, it is also the regular Hebrew word for “atonement,” as in Leviticus 17:11, for example. In essence, therefore, this is the first mention of “atonement” in the Bible. Whatever the exact nature of this”pitch may have been, it sufficed as a perfect covering for the Ark, to keep out the waters of judgment, just as the blood of the Lamb provides a perfect atonement for the soul.
The Ark also had a “window” (Hebrew tsohar), which probably means, literally, an “opening for daylight.” Although the phraseology is difficult, most authorities understand that this “window” was to consist of a one-cubit opening extending all around the Ark’s circumference, near the roof, as provision for light and ventilation. Presumably there was also a parapet provided to keep out the rain.
The word for “ark” (Hebrew tabhah) is not the word used later for the “ark of the covenant,” but it is the word used for the ark of bulrushes in which Moses was hidden as a baby (Exodus 2:3). it seems, therefore, to be a very ancient word for a box meant to float upon water. At the time Noah began building his Ark, it must have seemed ludicrous to his antedilulvian contemporaries. They had never seen any kind of flood, or even rain (Genesis 2:5), and Noah’s preaching and construction work no doubt gave them much occasion for ridicule. — Morris, pages 181-183
The word for “flood” (mabbul), used here [Genesis 6:17] for the first time, applies only to the Noahic Flood; other floods are denoted by various other words in the original. This was the “mabbul,” unique in all history. … Since mabbul is used only in Psalm 29:10, outside of Genesis 6–9, the cataclysmic activity poetically described in Psalm 29 must also refer to the Noachian Deluge. Similarly, when the Genesis Flood is referred to in the New Testament, the Greek term kataklusmos is uniquely employed (Matthew 24:39; Luke 17:27; 2 Peter 2:5; 3:6) instead of the usual Greek word for “flood.”
The Flood would not only destroy mankind, but also “all flesh,” wherein is the breath of life, from under heaven.” This phrase indicates again that animals, like men, have the “breath” (rauch, “spirit”) of life. The phrase “under heaven” qualifies the destruction as applying to land animals only, as does also the statement “everything that is in the earth [or ‘land].” The Flood would not destroy all marine species. … Such language, of course, is utterly inconsistent with the idea of either a local flood or a tranquil flood. — Morris, pages 183-184.