container ships were not around those days yet, and don't forget that the first container ships were converted tankers.....
First container ships were converted merchant ships, not tankers. The idea of containers originated with the use of the Seatrain boats, and later some American shipping lines converted their C2 or C3 types to carry containers, by adding a squared addition to the hull, sometimes it was wider than the original hull (like SS Ponce, or Pacific Banker). Later it was considered better to convert tankers because they had their engines aft, thus leaving the whole hull foreward free. Also ships converted were the C4 type which also had engines aft. IIRC the Seatrain ships were also converted to containers, after Cuba was closed to US commerce with the rise of Castro to power there.
BTW most of the ships mentioned above will be done, as part of my ongoing MARAD ships project.
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Thank you Kim for the crest
"Never fear to try on something new. Remember that the Titanic was built by professionals, and the Ark by an amateur"