Using Genesis's dimensions, Noah's Ark had an approximate length-to-width ratio of 6 to 1.
Genesis 6:15 gives the ark as 300 cubits long and 50 cubits wide. Dividing 300 by 50 produces 6, so the vessel's stated length was six times its width. The calculation does not require knowing the exact modern length of a cubit.
The same verse gives the height as 30 cubits, making the stated dimensions 300 by 50 by 30 cubits. These proportions describe a long, rectangular vessel. Naval engineers and modern replicas sometimes discuss the ratio because a broad hull can provide stability, but the biblical text does not present a modern engineering analysis.
A cubit was an ancient unit whose exact length varied by culture and period. That uncertainty affects the ark's absolute size, but not the 6-to-1 ratio derived from the three Genesis numbers.