slave ships could be at sea for more than a few months.
A month or two.
It took 2 months for the mayflower to sail to America. See related link.
How long did it take for sir Walter Raleigh to sail across the world
it takes about 18 hours by plane
It took about 6-8 weeks to sail.
Forever, blbe
66 days
7 days
it took 4 months from africa to america
It depends on the type of boat that you are using.
In the 18th century about 6 months