Genesis 6:14-16

"Make thee an ark of gopher wood; rooms shalt thou make in the ark, and shall pitch it within and without with pitch. And this is how thou shalt make it; the length of the ark three hundred cubits, the breadth of it fifty cubits, and the height of it thirty cubits. A light shalt thou make in the ark, and to a cubit shalt thou finish it upward; and the door of the ark shalt thou set in the side thereof; with lower, second, and third stories shalt thou make it."

It is impossible from this description for men to make a diagram or replica of the ark, only the overall dimensions being recounted here. Nevertheless, what we know of it is impressive enough. Of course, the length of a cubit (usually held to be the length from the elbow to the tip of the extended middle finger) is uncertain, but about 18 inches is the minimum length assigned to it. Following that estimate, the size of the ark was 450 feet long, 75 feet wide, and 45 feet high. Schaeffer stated that these are almost exactly the dimensions of The Great Eastern, the great ship used in laying the first North Atlantic cable.[14] Those dimensions would give a reading of over 1,500,000 cubic feet, with over 100,000 square feet of deck space. The displacement tonnage of such a vessel has been placed at 43,000 tons,[15] with a pay-load capacity of 32,800 tons.[16]

"Gopher wood ..." It is not known exactly what this was, but it is usually supposed to have been cypress, of which wood there is an abundance in the upper Mesopotamian valley where the ark is supposed to have been built. The "pitch" was asphalt, or some other petroleum derivative. It would have had the utility of making the craft watertight.

The ark was not designed to sail, but merely to float.

"And this is how thou shalt make it ..." Of particular importance is the fact of God's having given the dimensions and specifications for the ark. Noah was not a boat-engineer, and just as God later showed Moses the pattern for the tabernacle, so also here, God gave the pattern of that which saved Noah and his family. The pattern came from God. In view of this recurring fact in Scripture, it is a gross error to suppose that men may make God's church after any pattern they wish to follow.