[BroJoeK]

"Every ship carrying slaves that was registered in the USA and home ported in New England."

Southern cities like Charleston, SC, had thriving ship-building & shipping industries which began to fade away at about the same time (1807) the United States made it illegal to import slaves from abroad.

Restoring both the international slave-trade and Southern shipping was a major objective of secessionists in 1860.

[rxh4n1]

Not so. The Confederate Constitution banned the importation of slaves.

[DiogenesLamp]

You left out US federal contracts for northern shipping (New York mostly) that made it impossible for Southern shipping companies to compete with them.

Fishing subsidies, mail carrying contracts and other such set asides to protect New York's industries, and mostly paid for by the Southern states which contributed 73% of the total US Federal budget.