Interesting that both slave ships were built in northeastern states and operated out of New York and Louisiana.
From New York City's Slave Market
"By the 1850s, the city [i.e., NYC] was dominating the illegal international slave trade to the American South, Brazil, and Cuba. New York benefited much from slavery and the slave trade: southern cotton and sugar sailed to Europe from its harbor. Banks, insurance companies—among them Aetna, JP Morgan Chase, and New York Life—and lawyers made a brisk business with slaveholders and slave ship owners. Traders and builders outfitted slave ships."