On her first three voyages at least, the mortality rate among the slaves during the Middle Passage was so low that John's master and surgeon qualified for a bonus payment.

[2] 1st voyage transporting enslaved people (1791): Captain Patrick Ryan sailed from London on 4 January 1791.

[3] 2nd voyage transporting enslaved people (1791–1792): Captain John Frazer sailed from London on 23 December 1791, bound for West Africa.

3rd voyage transporting enslaved people (1792–1793): Captain John Frazer sailed from London on 14 October 1792.

John started acquiring captives at Cape Coast Castle on 14 October 1792, stopped at Annobon, and left Africa on 9 July 1793.

4th voyage transporting enslaved people (1794): Captain George Haliburton sailed from London on 3 March 1794.

[6] William Collow sold John and her new owners apparently decided to sail her as whaler.