Thames sailing barge

Thames sailing barges, with typical red-brown sails, in the East Swin, off Foulness Point

A Thames sailing barge is a type of commercial sailing boat once common on the River Thames. They are flat-bottomed barges, adapted to the Thames Estuary, which is not deep and has narrow tributary rivers. The larger barges could be taken on the sea, and were the largest sailing vessel to be handled by just two men. The average size was about 120 tons and they carried 4,200 square feet (390 m²) of canvas sail in six working sails. They carried heavy cargo to English ports and to Europe. At first they were all made of wood, but some later ones were made of steel. They were about 20 feet wide and 80 or 90 feet long with two masts.

In the 1860s barge races were started, and the barges' design improved as they were built with better lines in order to win. The Thames barge races are the world's second oldest sailing competition, second to the America's Cup.