Rebel Cargo by James Riordan

Rebel cargo is the story of an Ashanti girl and an English boy as they are both sold into slavery.
Abena is an Ashanti girl sold into slavery on the notorious Transatlantic route from West Africa to Jamaica. Mungo is an English orphan who becomes a cabin boy, only to be kidnapped and sold as a white slave. Fate brings the two together and Mungo, risking life and limb, saves Abena from a terrible death.