In June 1946 the Greek press cited a report by Reuters that Onassis had acquired 10 ex Canadian corvettes (frigates depending on source) at a price of $1 million (0.75 mil also reported). The corvettes would be converted in Canadian shipyards to cargo ships for use in the Med.
As far as I know, the conversions never materialized. If this sale actually took place, then maybe the ships languished until Onassis used them for the whaling business.