There was a time back in the early 1800’s and before bridges were built across The River Thames that the Thames Sailing Barge was the main form of river commercial transport. With a good wind they could make their way up the river and on the return would drift downstream at the river flow rate, while the bargee’s would steer the barge with an oar somewhat like that of a Gondolier in Venice.
To cross the river at that time was either by fording at a shallow point, or by using a chain ferry that were just coming into use at that time. When bridge building took place sailing was no longer possible and the use of horses became to the preferred method of power to tow the barges.
In this 1818 watercolour print of Cliveden Reach you can see two barges on their way down stream. It seems that the artist was seated by Formosa or close to it.