"Make for yourself an ark from resinous wood. You will make compartments in the ark and cover it with tar inside and outside." - Genesis 6:14
Because, you know, that's how you build a giant boat - just wood and tar. No nails. No iron or steel bands to hold things together. No beveling to interlock the keel with the super structure. Just wood and tar . . .
"When another notoriously large ship, the Great Michael, was built in 1511 (though only 1/4 the size of the ark), it was said to have taken all the woods of Fife (a county in Scotland famous for its shipbuilding), as well as having to import wood from France, other areas in the Baltic sea, and cargo ships scrapped for use in its construction. A ship of Noah's size would have required tens of thousands of high quality timber to be cut and milled for its construction, something that is not exactly feasible considering the Ark was supposedly built in what is modern day Iraq."
-Rational Wiki