The South Spainer was published from 1963-1966. Copies in the MacMullen Library at the San Diego Maritime Museum.
I get the impression that a 'South Spainer" was a ship that sailed to the former Spanish realms in America- but just an impression (See quote from book chapter, below, where a "South Spainer" is definitely a sailing ship- possibly carrying passengers as well as cargo).
Now if someone in San Diego would check No. 1 of the journal at the MacMullen Library, he might find a definition.

From chapter five of "Before the Mast- and After," 1924, by Sir Walter Runciman (an expensive title now, but apparently in Gutenberg, on line).
"Long experience had made Joe familiar with every harbour, cross-current, shoal or rock from the Tyne to London or Calais. Joe was strangely ignorant of the etiquette of the South Spainer quarter-deck, and his fluent gruff phrases were untrammelled in their scope."
www.guernsey.net/~sgibbs/runciman/bma/1-p5-ch5.txt