Hat tip to Hemant for calling my attention to this article by Danny Faulkner, a young earth creationist astronomer, wherein he does “research” to determine the exact length of the (entirely mythical) global flood. Did it last a literal year, 365 days, or 371 days? Let’s go to the lab and do us some scientific researchin’.

Belief that the Flood lasted 371 days is common among recent creationists, but there are other possibilities. I argue that the Flood’s duration most likely was 365 days, exactly one year. At any rate, all possibilities for the length of the Flood are about one year, though not necessarily greater than one year. Therefore, I suggest that the best short answer to the question of how long the Flood lasted is “about one year.”

Many recent creationists are of the opinion that the Flood’s duration was 371 days. This belief is in agreement with and probably has been influenced by Whitcomb and Morris (1961, p. 3). However, Whitcomb and Morris did not produce the calculation for this, but merely reproduced a table that they referenced from Kevan (1953, pp. 84–85). Interestingly, Kevan did not endorse this figure as the length of the Flood. Rather, he preceded his table with the statement that the Flood chronology may be constructed this way, but he followed the table with the remark that this result assumes a 30-day month. He further noted that the synodic month1 actually is 29.5 days, and from this Kevan concluded that the Flood’s duration was 365 days. Hence, Kevan actually endorsed the theory that the Flood lasted exactly one year. The manner in which Kevan presented his table suggests that the idea of the 371-day Flood duration preceded him in the literature, but if it does, he failed to reference it.

It is clear that belief in the duration of 371 days for the Flood relies upon the assumption that the Flood account of Genesis 6–9 was based upon a calendar that used twelve 30-day months….

But how well-founded is the 30-day month and a 360-day year in ancient calendars? Several authors have approached this question recently. Boyd and Snelling (2014, pp. 6–7) briefly discussed several possible calendars that may have been in use in Noah’s time, without reaching any firm conclusion. Similarly, Boyd et al. (2014, pp. 52–54) also discussed various possible calendar choices.2 Anderson (2014, pp. 194–195) noted five fixed dates in the Flood narrative, but also commented that the exact duration of time depended upon which calendar was in use. Longacre (2014, pp. 233–234, 269–270) pointed out that 4Q252, a Qumran commentary on Genesis, apparently endorsed a 364-day calendar. However, these authors were not as concerned with the exact duration of the Flood as they were in establishing the relative chronology of the Flood for the purpose of using subtle clues in the biblical text in developing a geological Flood model.

Recently Faulkner (2012) criticized the belief that prior to the Flood the year consisted of exactly 360 days divided into 12 months that were exactly 30 days long. Nearly everyone who believes in this alleged pre-Flood calendar also subscribes to the 371-day length of the Flood, but the converse is not necessarily true. Here I must repeat some things from my earlier paper, and the reader is referred to that paper for some of the details. I will show here that there is a good case to be made for the Flood lasting one year (365 days) as Kevan did.