Whilst there are horse drawn barges that can operate on small river (navigable), I can't seem to find a passenger boat that can do the same, in the 1750s.
Surely if by definition it is navigable, there must be boats that can do so, and they ought to be available for all cargos, from the start?
Market narrowboat, available in 1761, small river or narrow canal, 25 passengers.
But what about 1750-1761?
I will have to add a rowing boat when I get a chance. Apparently, these were used as ferries on rivers.