Airmail from the mainland to a seagoing vessel

The airmail service was undergoing rapid development in the late 20s and early 30s. Trial flights were conducted from seagoing vessels using small aircraft that departed from those ships on the open sea with mail to the mainland, in order to deliver it to the addressees sooner. These were the so-called catapult flights. The ships were then still about 1000 kilometers from the port. The catapult flights took place for the first time in August 1928 from the French ship 'Ile de France'. This was announced in a newspaper on August 13, 1928: An airmail service from ships to the mainland was opened on Monday from the steamship Ile de France, shortening the crossing time for the mail by almost a day. The catapult flights to New York from the German ships 'SS Bremen' and 'SS Europa' became very famous. These flights were also carried out in the other direction, from New York to Germany. Mail flights from ships to the mainland took place not only on the Atlantic Ocean, but also on the Pacific Ocean. This was not done with airplanes, but with an airship. Fifty miles from the coast, Goodyear's airship 'Volunteer' picked up bags of mail from the deck of the steamship 'City of Los Angeles' and delivered them to the roof of the post office in San Pedro, California. There, the mail was stamped using a stamping machine and provided with a green imprint of a Chamber of Commerce stamp on the back. Afterward, the mail followed the normal postal route, in this case to Newark, where the letter arrived on June 15, 1931. Much less well known is that mail from Honolulu (Hawaii) was transferred by plane to the steamship 'City of Los Angeles' in January 1931 by dropping the mailbags onto the deck. The aircraft was a Ford Trimotor. The 'City of Los Angeles' already had a long history behind it. Built in 1899 for the North German Lloyd under the name 'Grosser Kurfürst', this ship sailed between Bremen and New York. In 1917, it was seized by the United States and used as a troop transport ship under the name 'Aeolus'. In 1922, the ship was acquired by the 'Los Angeles Steamship Co.' and renamed 'City of Los Angeles'. The ship maintained a regular service between Los Angeles and Honolulu, including the experiment with airmail delivery in January 1931. The waterproof mailbag that was lowered onto the deck contained 12.527 envelopes, each of which was numbered. The envelope in my collection is numbered 9.419. Furthermore, an imprint of a signature was applied, as well as the ship's onboard stamp. It was the largest airmail shipment to leave the Honolulu post office at once. Most of the envelopes were manufactured by AC Roessler of East Orange, New Jersey. The details regarding the aircraft and the ship were taken from official publications from 1931. I still wonder why the date January 30 is included in the Honolulu stamp impression. The green impression of the vignette lists the date January 24, 1931, as well as a different type of aircraft. The violet impression of the ship's stamp also shows the date January 24, 1931. Who is right here? The official publishers or those who manufactured the stamps? And whose signature is it?