The vessels were small, many of them half the size of the lighters that ply sluggishly up and down New York harbor.

Sloops, schooners, brigantines, and scows of 40 or 50 tons burden, carrying crews of nine men including the captain and mates, were the customary craft in the early days of the eighteenth century.
In his work on "The American Slave-Trade," Mr.John R.Spears gives the dimensions of some of these puny vessels which were so heavily freighted with human woe.

The first American slaver of which we have record was the "Desire," of Marblehead, 120 tons.

Later vessels, however, were much smaller.

The sloop, "Welcome," had a capacity of 5000 gallons of molasses.
The "Fame" was 79 feet long on the keel--about a large yacht's length.