Dear Jeffrey,

Without being 100% sure, I would say that the first step is to check here : http://www.frenchlines.com/en/
Then depending on the name of the ships, you may ask them to search for the ship manifest (I guess this is the list of passengers)

A second step here : https://www.ancestry.fr/search/collections/7488/

Sometimes, you have also some Archives in the port of registration of each ship (Le Havre mainly) - but this would be more about the equipage's names (Captain and others)

otherwise, Ellis Island records that you may already know are most of the time enough to complete a family or dates

hope that helps

Regards
David