Mahommah Gardo Baquaqua and Olaudah Equiano are examples of Africans from the diaspora who left behind autobiographies of note and for whom sailing was an experience relevant to the shaping of liberty. Equiano, for example, became familiarized with sailing equipment in the slave ship that transported him to Barbados, despite the terror instilled in him by the voyage. By observing a sailor who was using a quadrant, he deduced how the instrument - which seemed to possess magic powers - worked. After working in the Caribbean and in the state of Virginia, Equiano was taken to Great Britain, from where, still enslaved, he would set sail for the waters of Northern Europe and the Mediterranean, learning sailing and artillery techniques (Silva, p. 88, p. 95). Deep-sea sailing remained ubiquitous among Africans and people of African descent, whether enslaved or freed people, over time and in different regions covered by the slave trade. It displayed traces of African traditions surrounding fishing, trade, the sexual division of labour and geographical mobility. Enforcers of and participants in the practices of nautical navigation, Africans and their descendants experienced the transformations implemented in these same practices. The experience of men such as those mentioned above had much in common with those of thousands of other African sailors in the diaspora (Bolster, 1990, 1997).  
This experience may be traced more accurately by consulting ships' crew records, the keeping of which was initiated in a systematic fashion in Portugal in the second half of the eighteenth century. As mentioned above, the crews of merchant ships also included freed and enslaved people with specialized skills; Portuguese sources provide information on the roles most frequently performed by the men. This is because Portuguese merchant fleets included a higher number of African sailors than English or French ships (Knight, Talib and Curtin, 2010, p. 887).