My familiarity with the cubit comes entirely from a comedy routine about Noah by the disgraced comedian who won’t be named (rhymes with Frill Frosby). In that bit, God tells Noah to build an ark.
…God: I want you to build an ark.
Noah: Right … What’s an ark?
God: Get some wood and build it 300 cubits by 80 cubits by 40 cubits.
Noah: Right … What’s a cubit?…
Judging by the fact that cubits were described in terms of measuring a length, width, and height we can deduce that a cubit is a unit of linear distance.
Since God didn’t answer Noah in Pill Plosby’s comedy routine, we’ll have to look elsewhere for the answer.
The cubit, generally taken as equal to 18 inches (457 mm), was based on the length of the arm from the elbow to the tip of the middle finger and was considered the equivalent of 6 palms or 2 spans. In some ancient cultures it was as long as 21 inches (531 mm).
So, if the ark indeed was meant to be 300 cubits by 80 cubits by 40 cubits, that would make it roughly 450 x 120 x 60 feet. That’s a little more than half the length of the Titanic, and a little less than a third the length of today’s largest cruise ship.
According to the Online Etymology Dictionary cubit as coming “from Latin cubitum, cubitus “the elbow, the forearm,” generally regarded as a derivative of PIE *keu(b)- “to bend,””