The USS Irex SS-482: Commemorative Cover 1948

This is an interesting item because it is to some extent bogus. The stamp was issued on 5 December 1947, which would be appropriate, and the cancellation of 5 January 1948, Portsmouth Naval Yard seems authentic. The cachet refers to testing of the snorkel, and indeed around this time the Irex was in fact testing the snorkel.

But then come the inconsistancies. The Irex spent July 1947 to February 1948 evaluating the snorkel during sea tests, but as far as I know, this never involved a return to Portmouth. While the cover might commemorate the achievement of the Yard when the snorkel tests were complete, the official date for the completion of those tests was in February, not January. What is more seriously out of place is the photo of the Irex as it existed only after acquiring the fiberglass sail in July 1957. Also, there was yet no institution known as the “U.S. Naval Historical Center” in 1949. It seems the cachet design was invented well after the fact and added to make the cover more saleable.