The traditional sail trading vessel of the upper Nile. They were not unlike the nugger of the lower Nile but mostly had only one mast and spread a very large lateen sail on a yard twice as long as the mast and as long as, or longer than, the vessel itself. Some of the larger gyassis carried two masts with normal lateen sails. They were all flat bottomed with broad, square sterns and large rudders like barn doors.
Subjects: Maritime History.