[Note] please see some background to C.H.J. Snider's comment "3-2-3" as being Morse for "SOS" in "Passing Hails" below.
Mr Snider, and his corresponent, are partially correct in writing that "3-2-3" or "... .. ..." or dit-dit-dit dit-dit dit-dit-dit represent "SOS" in Morese code. However, many readers will take this as an error, as a Morse transmission would be "... – – – ..." or dit-dit-dit dah-dah-dah dit-dit-dit. The confusion is between what was the American Morse Code and the Internatioal (ITU) Morse Code.
In 1912, The Radiotelegraphic Convention met in London and clearly stated that "The signals to be employed are those of Morse International Code." However, the use of "American code" took years to die out, and the Great Lakes shipping community was particularly slow to adapt. This article (1945) is however the most extreme example, time-wise, that we have found.
For the technically curious, in American code, both "I" and "O" were composed of two "dits", but "I" only had a single space (timed as equivalent to a single dit) between them, whereas "O" was prolonged with a double space.