It all starts in February 1929 when Dell Publishing launch a new pulp called Navy Stories, issued monthly at a price of 20c for 128 pages, and edited by Eugene A. Clancy. After three issues, this is "joined" by a slimline sister magazine called Submarine Stories, also edited by Clancy - which contained only 64 pages and sold for 10c. This experiment didn't appear to be a success as, AFAIK, no second issue ever appeared.
Meanwhile, Navy Stories continued on a monthly basis until #8 in September 1929. Then something rather strange happened. Nothing appeared in October, and in November an issue of Submarine Stories appeared continuing the numbering of Navy Stories. Then there was nothing until March 1930 when another issue of Submarine Stories appeared also continuing the numbering.
So far so good, except that now Dell decided to revive Navy Stories and ran it in alternating months with Submarine Stories. However, rather than continuing the numbering between the two magazines, the consecutive numbering continued ONLY in Submarine Stories, with Navy Stories reverting to #1 (even though it was the numbering of Navy Stories that had been usurped by Submarine Stories).
Thus, the issues ran as follows: