Allegory or allegorical interpretation is only one of several ways of interpreting Scripture. The Bible contains myth, fiction, some history, theology, biography and more and some books contain more than one genre. If there was only one way of interpreting Scripture we wouldn’t need a magisterium. I think it is important to rely on both right reason and Faith which will not contradict each other. I found the following material to be most appropriate to these discussions on Noah’s Ark.
In his book Thomas E. Woods Jr.( How the Catholic Church Built Western Civilization) has a quotation from Edward Grants book “Science and Technology in the Middle Ages” which is attributed to Thomas Aquinas. It says as follows:
“First, the truth of Scripture must be held inviolable. Secondly when there are different ways of explaining a Scriptural text, no particular explanation should be held so rigidly that, if convincing arguements show it to be false, anyone dare to insist that it still is the definitive sense of the text. Otherwise unbelievers will scorn Sacred Scripture and the way to faith will be closed to them.”
In this day when there is sufficent archeological and/or scientific evidence that contradicts certain historical or scientific parts of the Scriptures it seems obvious that biblical history and science in the Old Testament needs be taken as carrying only theological truth. So what is to be made of narratives like the Creation, the Exodus, Noah’s Ark, David and Solomons Kingdom and such like?
On the contrary, It is written (Genesis 1:6): “God said: let there be a firmament,” and further on (verse 8); “And the evening and morning were the second day.”
I answer that, In discussing questions of this kind two rules are to observed, as Augustine teaches (Gen. ad lit. i, 18). The first is, to hold the truth of Scripture without wavering. The second is that since Holy Scripture can be explained in a multiplicity of senses, one should adhere to a particular explanation, only in such measure as to be ready to abandon it, if it be proved with certainty to be false; lest Holy Scripture be exposed to the ridicule of unbelievers, and obstacles be placed to their believing.