Sea Post Courtesy Cancels

I fished out three lovelies from a bargain bin last weekend. These appear to all be from U.S. flagged ships, cancelled in the summers of 1934 and '35. They are on letterhead of the SS President Harding, President Monroe and President Polk. It looks like whomever created these had the ships' postmasters provide not only the standard Sea Post cancels, but all the auxiliary markings that were in use. Some interesting stuff here! Several of these saw very infrequent use and would probably be quite rare on cover. I don't really understand the Harry Deitch marking on the SS President Polk sheet.

Was it common practice to cancel courtesy sheet like this? Can anyone post other examples?

Nice. Particularly like the Polk.

These are likely "favor" cancels (and markings), obtained by a collector who travelled. I've acquired the same sort of markings from small town post offices as I travelled around my area.

I would imagine that Harry Dietch was a postal clerk on the USS Polk, and this device used by him in his capacity in that position when signing his name would be required.

Good info. Can anyone explain the SPO T4 cancellation on the SS Pres. Harding sheet? And what does the abbreviation U.S.T.P. mean?

SPO = Sea Post Office. T = taxe or tax. This was a postage due marking. 4 = code letter (and not a rate). From the 4 used in the killer of the same ship and the numbers used in killers for the other President Lines ships, 4 was used for SS President Harding.

Thanks hy-brasil! And I figured out that USTP stand for U.S. Trans-Pacific.

I wonder if there is a listing of which sea post numbers were assigned to which ships. I see that 24 shows up on all the SS Pres. Polk cancellations, and 15 was assigned to SS Pres. Monroe.