Dear Bram

Judging from the fact the four corvettes were towed from the US in early 1950, it seems to me that the sale must have been done in 1949.
I think the sale of HERMAN F.WHITON (later OLYMPIC CHALLENGER) to Onassis in July 1949 leads to the same conclussion, that he was preparing to enter the whaling business already since 1949.

Concerning "RIO GRANDE", the "RIO" prefix reminded me of RIO MARINA (ex USS ALACRITY PG 87, ex-HMCS CORNEL) that was rebuild in 1950 as the Italian ferry PORTO FERRAIO for Nav.Toscana. Her Italian fleetmate was PORTO AZZURRO (ex USS HASTE PG 92, ex HMCS MANDRAKE)